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Breakthrough study finds genetic link to Parkinson's and ADHD

<p>A major scientific study has found a surprising link between the genes that control brain size and the risk of brain-related conditions. </p> <p>A Queensland Institute of Medical Research Associate Professor Miguel Renteria led an international team of experts who scanned DNA data and MRI scans from 76,000 participants.</p> <p>“Genetic variants associated with larger brain volumes in key brain regions also increase the risk of Parkinson’s disease, while variants linked to smaller brain volumes in key regions are associated with an increased risk of ADHD,” Renteria said. </p> <p>“It brings us closer to answering key questions about how genetics influence brain structure, and how we can potentially treat these conditions in future.”</p> <p>Parkinson’s Australia CEO Olivia Nassaris has celebrated the results of the study, saying the surprising results open the door to future treatment options for Parkinson’s, which currently has no cure or cause.</p> <p>“The more answers we have the closer we are to understanding this condition,” she said.</p> <p>Michael Wiseman, who has been living with Parkinson’s for eight years, said he is pleased more research is being done about the neurodegenerative condition.</p> <p>“I know it’s not going to benefit me in any way, as far as a cure or anything … I just hope they keep going, kicking some goals and finding results because it’s an insidious sort of thing, it’s a passenger I’ll have until I go to the grave.”</p> <p><em>Image credits: Shutterstock </em></p>

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Trying to lose weight? Here’s why your genetics could be just as important as your exercise regime

<div class="theconversation-article-body"> <p><em><a href="https://theconversation.com/profiles/henry-chung-1279176">Henry Chung</a>, <a href="https://theconversation.com/institutions/university-of-essex-1291">University of Essex</a>; <a href="https://theconversation.com/profiles/chris-mcmanus-2226445">Chris McManus</a>, <a href="https://theconversation.com/institutions/university-of-essex-1291">University of Essex</a>, and <a href="https://theconversation.com/profiles/sally-waterworth-2226444">Sally Waterworth</a>, <a href="https://theconversation.com/institutions/university-of-essex-1291">University of Essex</a></em></p> <p>Weight loss is a complicated process. There are so many factors involved including your diet, how much sleep you get each night and the kind of exercise you do. Our recent study shows that your <a href="https://www.tandfonline.com/doi/full/10.1080/02701367.2024.2404981">specific genetic profile</a> may also have a dominant effect on how well you lose weight through exercise. This might explain why two people who do an identical workout will see very different results.</p> <p>We identified 14 genes that appeared to significantly contribute to how much weight a person lost through running. This suggests that some of us have a natural talent when it comes to burning fat and losing weight through exercise.</p> <p>To conduct our study, we recruited 38 men and women born in the UK aged between 20 and 40. None of the participants regularly exercised at the start of the study. The group was randomly divided, with one half following a strict eight-week endurance programme that consisted of three weekly runs of 20-30 minutes.</p> <p>The other group acted as a <a href="https://www.britannica.com/science/control-group">control</a>. They were instructed to refrain from exercise and continue their daily routines as normal over this study period, including diet and lifestyle habits.</p> <p>All participants conducted a running test to see how far they could run in 12 minutes, and were weighed before and after the study period. This was to gauge their initial fitness level and see how much they changed over the duration of the study. <a href="https://www.nhs.uk/conditions/obesity/">Body mass index</a> (BMI) was also calculated.</p> <p>Additionally, a saliva sample was collected from each person with a <a href="https://muhdo.com/?gclid=Cj0KCQjwiIOmBhDjARIsAP6YhSUB3WI81JP4Q_snYLhh-SBVNeCJNy2m63C8bKJFvO-nJ5UsHuCCdqMaAhTeEALw_wcB">DNA test kit</a> at the end of the study to assess their unique genetic profile.</p> <p>It’s important to note that everyone who participated in the study had a similar body weight, BMI and aerobic fitness level at the start of the study. This is beneficial for <a href="https://casp-uk.net/news/homogeneity-in-research/">multiple reasons</a>. It meant everyone was at the same starting point, and some <a href="https://www.sciencedirect.com/topics/nursing-and-health-professions/confounding-variable">confounding variables</a> were already controlled for such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10128125/">fitness level</a>. This ultimately improves accuracy in interpreting the results.</p> <h2>Exercise genes</h2> <p>Everyone in the exercise group managed to lose weight – around 2kg on average. The control group, on the other hand, put on a little bit of weight.</p> <p>While a 2kg weight loss may not sound like a lot, it’s significant considering the exercise regime only lasted eight weeks and participants made no <a href="https://www.intechopen.com/chapters/87186">changes to their diet</a>.</p> <p>More significant, however, was the large variation in results among those that exercised – with an up to 10kg difference in weight loss between some of the participants. In fact, everyone within the exercise group improved at different rates.</p> <p>Since we controlled for factors such as the <a href="https://pubmed.ncbi.nlm.nih.gov/3529283/">intensity, duration and frequency</a> of the exercises and used participants who’d had a similar body weight and fitness level at the start of the study, this suggests that some people naturally benefited more than others from endurance training.</p> <p>When we looked at the genetic profiles of our participants, we found that differences in each person’s response to the exercise was strongly associated with their specific genetics.</p> <p>We showed there was a strong linear correlation between the amount of weight participants lost and 14 genes that have previously been shown to be associated with body weight, metabolism or <a href="https://www.nature.com/articles/s41380-018-0017-5">psychological conditions</a> that affect BMI. The greater number of these genes a participant had, the more weight they lost. Our results also revealed that around 63% of the variance in weight lost among participants were explained by the genes identified.</p> <p>For example, research has shown the <a href="https://www.ncbi.nlm.nih.gov/gene/10891">PPARGC1A gene</a> plays a role in metabolism and the <a href="https://link.springer.com/article/10.1007/S11033-020-05801-Z">use of fats for energy</a> while exercising. Our study found that all participants who lost more than 1.5kg from exercise had this gene. Those who lost less than this did not have this gene.</p> <p>Our findings align with what <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249501&amp;s2=P875440273_1683331208925004155">previous studies</a> have shown. But while previous papers have only looked at the link between individual genes and weight loss, ours is the first to show that 14 different genes appear to work in combination to affect whether a person loses weight from endurance exercise.</p> <h2>Piece of the puzzle</h2> <p>Our study also suggests that while some people possess genes that make it easier for them to get fit and lose weight, people with these favourable genetics can only flourish if they actually exercise. In fact, our control group also had a number of these listed genes, but without exercise these genes could not activate, and so the participants did not lose any weight.</p> <p>While our study provides compelling findings, it’s not without limitations. Since we only looked at endurance-based exercise, it will be important for future studies to investigate whether there are similar links between weight loss, genetics and combinations of different types of training (such as a mixture of endurance and strength sessions into a training plan).</p> <p>It’s also worth mentioning that exercise is only <a href="https://www.who.int/activities/controlling-the-global-obesity-epidemic">one piece of the puzzle</a> when it comes to weight loss. So even if you have all 14 of these genes, you won’t lose any weight or get fit if you don’t exercise and maintain a healthy diet and sleep pattern.</p> <p>On the flip side, someone that only has a few of these favourable genes can still benefit if they exercise and are mindful of other aspects of their lifestyle.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/240506/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https://theconversation.com/republishing-guidelines --></p> <p><em><a href="https://theconversation.com/profiles/henry-chung-1279176">Henry Chung</a>, Lecturer in Sport and Exercise Science, <a href="https://theconversation.com/institutions/university-of-essex-1291">University of Essex</a>; <a href="https://theconversation.com/profiles/chris-mcmanus-2226445">Chris McManus</a>, Lecturer, School of Sport, Rehabilitation and Exercise Sciences, <a href="https://theconversation.com/institutions/university-of-essex-1291">University of Essex</a>, and <a href="https://theconversation.com/profiles/sally-waterworth-2226444">Sally Waterworth</a>, Lecturer, School of Sport, Rehabilitation and Exercise Sciences, <a href="https://theconversation.com/institutions/university-of-essex-1291">University of Essex</a></em></p> <p><em>Image credits: Shutterstock </em></p> <p><em>This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/trying-to-lose-weight-heres-why-your-genetics-could-be-just-as-important-as-your-exercise-regime-240506">original article</a>.</em></p> </div>

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Chris Hemsworth’s Alzheimer’s gene doesn’t guarantee he’ll develop dementia

<p>Chris Hemsworth, famous for his role as the god Thor in Marvel Cinematic Universe movies, has announced he will be <a href="https://www.theguardian.com/film/2022/nov/21/chris-hemsworth-to-take-time-off-from-acting-after-discovering-alzheimers-risk" target="_blank" rel="noopener">taking a break</a> from acting after being told he has two copies of the <a href="https://www.nia.nih.gov/news/study-reveals-how-apoe4-gene-may-increase-risk-dementia" target="_blank" rel="noopener">APOE4 gene</a>, increasing his risk of Alzheimer’s.</p> <p>Having one copy of the <a href="https://www.science.org/doi/abs/10.1126/science.8346443" target="_blank" rel="noopener">APOE4 gene</a> increases your risk for Alzheimer’s 2-3 times. Two copies increases your risk 10-15 times.</p> <p>But the key here is “risk”. Having one or more copies of the gene doesn’t guarantee Chris or anyone else in a similar situation will go on to develop Alzheimer’s, the most common form of dementia.</p> <p><strong>Sharing the news</strong></p> <p>Hemsworth’s willingness to share his concerns about developing Alzheimer’s with millions should be applauded. It’s a reminder to all of us to keep an eye on our health and reduce our risk of future illness.</p> <p>Alzheimer’s, and dementia more broadly, is <a href="https://www.dementiastatistics.org/statistics/global-prevalence/" target="_blank" rel="noopener">set to challenge</a> health-care systems worldwide.</p> <p>In Australia alone there are <a href="https://www.dementia.org.au/statistics" target="_blank" rel="noopener">up to</a> 500,000 people with dementia, supported by almost 1.6 million carers. By 2036, about <a href="https://www.dementia.org.au/sites/default/files/NATIONAL/documents/The-economic-cost-of-dementia-in-Australia-2016-to-2056.pdf" target="_blank" rel="noopener">450 people</a> are predicted to be diagnosed daily. So understanding how APOE4 alters the risk for the major cause of dementia may be pivotal in preventing cases.</p> <p>But not all people with the APOE4 gene go on to develop Alzheimer’s. This means that there may be a combination of environmental factors interplaying with the gene that lead some people to develop Alzheimer’s, while others do not.</p> <p><strong>What’s APOE4 got to do with Alzheimer’s?</strong></p> <p>Most Australians have APOE3 or APOE2 genes. In Caucasians it’s only <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5531868/" target="_blank" rel="noopener">about 15%</a>, like Hemsworth, who have inherited an APOE4 gene.</p> <p>The APOE gene types are best known for their role in modulating the metabolism of lipids (fats), such as cholesterol and triglycerides.</p> <p>They code for synthesis of different versions of the protein APOE, with subtle differences in structure. The APOE proteins become an integral part of lipoproteins in the blood. These are the fat-carrying particles your GP measures to consider your risk of heart disease.</p> <p>APOE proteins have a similar function in the brain, to modulate lipid levels. But in the context of Alzheimer’s, researchers study it for its effect on the integrity of brain cells.</p> <p>Accumulating evidence <a href="https://www.sciencedirect.com/science/article/pii/S0197458022000550" target="_blank" rel="noopener">suggests</a> APOE4, is associated with brain inflammation and cellular damage.</p> <blockquote class="twitter-tweet"> <p dir="ltr" lang="en">APOE4 is the strongest genetic risk factor for Alzheimer’s disease. A study in <a href="https://twitter.com/Nature?ref_src=twsrc%5Etfw">@Nature</a> establishes a functional link between APOE4, cholesterol, myelination and memory, offering therapeutic opportunities for Alzheimer’s disease. <a href="https://t.co/bNsmDVPfFW">https://t.co/bNsmDVPfFW</a> <a href="https://t.co/58odE1JASl">pic.twitter.com/58odE1JASl</a></p> <p>— Nature Portfolio (@NaturePortfolio) <a href="https://twitter.com/NaturePortfolio/status/1594762841487249410?ref_src=twsrc%5Etfw">November 21, 2022</a></p></blockquote> <p><strong>Can we prevent Alzheimer’s?</strong></p> <p><strong>1. Look after your capillaries</strong></p> <p>Damaged and leaky blood vessels (capillaries) in the brain lead to inflammation, the death of brain cells and cognitive impairment. In fact, in Alzheimer’s, damaged capillaries are the earliest sign of the type of brain damage that causes disease.</p> <p>The protein encoded by the APOE4 gene may be less able to support healthy capillaries in the brain. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0163782709000563" target="_blank" rel="noopener">We suggested</a> APOE4 increases the abundance of specific complexes of lipoproteins and proteins in blood that silently damage brain capillaries, causing them to leak.</p> <p>We also see more brain capillary leakage in mice fed Western-style diets richer in saturated fats.</p> <p>The relationship between how the APOE proteins mediate lipid metabolism and capillary health in humans is poorly understood.</p> <p>But we have 60 years of research knowledge to say with confidence that eating foods good for the heart should also be good for the brain. This is particularly relevant for people with the APOE4 gene.</p> <p>So if you have the APOE4 gene and want to minimise your risk of Alzheimer’s, a healthy diet is a good place to start.</p> <figure class="align-center zoomable"><em><a href="https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=316&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=316&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=316&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=397&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=397&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/497142/original/file-20221124-24-rlqyk5.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=397&amp;fit=crop&amp;dpr=3 2262w" alt="Capillaries" /></a></em><figcaption><em><span class="caption">Looking after your capillaries with a healthy diet is a good place to start.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/system-many-small-capillaries-branch-out-1745173364" target="_blank" rel="noopener">Shutterstock</a></span></em></figcaption></figure> <p><strong>2. Give your brain a break</strong></p> <p>Reducing unnecessary stimuli to “give your brain a rest” may have big impact over decades of your life. The latter may be a more important consideration if you have the APOE4 gene.</p> <p>That’s because the APOE gene is also linked to how the brain uses energy, which may lead to more <a href="https://www.frontiersin.org/articles/10.3389/fnmol.2018.00216/full" target="_blank" rel="noopener">oxidative stress and damage</a>.</p> <p>While we’ve yet to collect robust data in humans, take a digital detox now and again, plan some down time, and avoid unnecessary stress if you can.</p> <p><strong>Should we test for the APOE4 gene?</strong></p> <p>Some people might be tempted to get tested for the APOE4 gene, especially if there’s a family history of Alzheimer’s.</p> <p>But unless genetic testing is going to change your treatment (for instance, by taking certain medications to slow progression of brain damage), or your behaviour to minimise your risk Alzheimer’s, then testing is not justified.</p> <p>We can’t change the genes our parents gifted us, but we can change our environment.</p> <p>Poor diet, every drop of alcohol you drink, obesity and diabetes, high blood pressure and sedentary behaviour <a href="https://www.dementia.org.au/risk-reduction" target="_blank" rel="noopener">all contribute, over time</a>, to poorer vascular health and increase your risk of dementia.</p> <p>We’re still learning about how these risk factors for Alzheimer’s interact with the APOE4 gene. But there is no reason we shouldn’t all take greater responsibility for minimising our risk of dementia now, whether we have the APOE4 gene or not.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/195094/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https://theconversation.com/republishing-guidelines --></p> <p><em>Writen by John Mamo. Republished with permission from <a href="https://theconversation.com/chris-hemsworths-alzheimers-gene-doesnt-guarantee-hell-develop-dementia-heres-what-we-can-all-do-to-reduce-our-risk-195094" target="_blank" rel="noopener">The Conversation</a>.</em></p> <p><em>Image: Instagram</em></p>

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Tiny discovery could explain why our brains beat Neanderthal brains

<p dir="ltr">Our brains are incredibly complex, even in comparison to some of our closest animal relatives - and now we’re one step closer to knowing why.</p> <p dir="ltr">Human brains are made up of a whopping 86 billion neurons on average, which is up to three times more than primates.</p> <p dir="ltr">In a breakthrough study, scientists found that one change in our genes helps our brains develop more neurons than other animals, as well as our extinct cousins, the Neanderthals.</p> <p dir="ltr">Although our brains are roughly the same size as those belonging to Neanderthals, ours are differently shaped and allowed us to create technologies that our cousins never did.</p> <p dir="ltr">A team of scientists at the Max Planck Institute of Molecular Cell Biology and Genetics went looking for differences between our and Neanderthal brains and focused on the neocortex, a region of the brain behind our foreheads that is the largest and most recently developed part of our brain.</p> <p dir="ltr">While focusing on a particular gene, called <em>TKTL1</em>, the team found that the chain amino acids that make up the gene in modern humans has just one difference from the same gene in Neanderthals and other mammals.</p> <p dir="ltr">After looking at previously published data, they found that <em>TKTL1 </em>was mostly expressed in progenitor cells - a type of cell that can become more specialised cells - called basal radial glia, which are responsible for producing neurons during development.</p> <p dir="ltr">To test their findings, the researchers introduced the gene into two groups of mice, which don’t express either version of the gene. One group received the modern version of the gene which humans have, while the other received the archaic version.</p> <p dir="ltr">The mice with the modern form of the gene went on to produce more basal radial glia, which then resulted in more cortical neurons developing, in comparison to those with the older version of the gene.</p> <p dir="ltr">Repeating the experiment in ferrets, which also carry the older version of the gene and have folds in their brains, they found that animals with the modern gene produced more neurons and had larger brain folds.</p> <p dir="ltr">Finally, they went to verify their findings in human foetal neocortex cells - this time by removing the <em>TKTL1 </em>gene. Cells without the modern gene produced fewer of the progenitor cells.</p> <p dir="ltr">Although they stress that additional genes may be behind why we have more neurons than our relatives, Wieland Huttner, one of the researchers involved, said the study “makes the point that this one gene is an essential player” for shaping our big brains.</p> <p dir="ltr">Christoph Zollikofer, a paleoanthropologist at the University of Zurich who wasn’t involved in the study, said the study presents a “smoking gun” showing how our brains are different from those of Neanderthals.</p> <p dir="ltr">The study was published in the journal <em><a href="https://www.science.org/doi/10.1126/science.abl6422" target="_blank" rel="noopener">Science</a></em>.</p> <p><span id="docs-internal-guid-0b806d03-7fff-5ff5-12ff-39d6b4aa5fd5"></span></p> <p dir="ltr"><em>Image: Getty Images</em></p>

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Keeping to the beat controlled by 69 genes – not just our feet

<p class="spai-bg-prepared">Are you a dancing queen or do you have two left feet? Turns out that keeping to the beat is partly to do with our <a class="spai-bg-prepared" href="https://www.nature.com/articles/news.2007.359" target="_blank" rel="noreferrer noopener">genetics</a>.</p> <p class="spai-bg-prepared">An international team of researchers conducted a study on the genetic variation of 606,825 individuals, all of whom completed a musical ability questionnaire (including “Can you clap in time with a musical beat?”), with some also participating in beat synchronisation experiments including telling rhythms apart (Phenotype Experiment 1) and tapping in time with music (Phenotype Experiment 2).</p> <p class="spai-bg-prepared">Of the participants, 91.57% said yes to the question, “Can you clap in time with a musical beat?” Those who said yes also scored higher in the rhythm perception and tapping synchrony experiments.  </p> <p class="spai-bg-prepared">Looking at the genetic variation, 69 genes showed significant difference between the rhythmic and arhythmic participants, with <em class="spai-bg-prepared">VRK2 </em>being the most strongly associated. This gene has been linked previously to behavioural and psychiatric traits (including depression, schizophrenia and developmental delay), suggesting a biological link between beat synchronisation and neurodevelopment.</p> <div class="newsletter-box spai-bg-prepared"> <div id="wpcf7-f6-p195164-o1" class="wpcf7 spai-bg-prepared" dir="ltr" lang="en-US" role="form"> <form class="wpcf7-form mailchimp-ext-0.5.62 spai-bg-prepared init" action="/science/biology/keeping-the-beat-genetics/#wpcf7-f6-p195164-o1" method="post" novalidate="novalidate" data-status="init"> <p class="spai-bg-prepared" style="display: none !important;"><span class="wpcf7-form-control-wrap referer-page spai-bg-prepared"><input class="wpcf7-form-control wpcf7-text referer-page spai-bg-prepared" name="referer-page" type="hidden" value="https://cosmosmagazine.com/people/" data-value="https://cosmosmagazine.com/people/" aria-invalid="false" /></span></p> <p><!-- Chimpmail extension by Renzo Johnson --></form> </div> </div> <p class="spai-bg-prepared">Several physiology traits also seemed to be linked to beat synchronisation, including processing speed, grid strength, usual walking pace, and peak respiratory flow. These may be linked to the evolution of language and sociality through music in early humans.</p> <p class="spai-bg-prepared">For modern humans, our ability to keep the beat may help to predict developmental speech-language disorders, and serve as a mechanism for <a class="spai-bg-prepared" href="https://www.frontiersin.org/articles/10.3389/fnhum.2021.789467/full" target="_blank" rel="noreferrer noopener">rhythm-based rehabilitation</a>, including for <a class="spai-bg-prepared" href="https://cosmosmagazine.com/science/biology/bilingual-patients-recover-better-from-stroke/" target="_blank" rel="noreferrer noopener">stroke</a> and <a class="spai-bg-prepared" href="https://www.nature.com/articles/s41598-017-16232-5" target="_blank" rel="noreferrer noopener">Parkinson’s disease</a>.</p> <p class="spai-bg-prepared">This study has been <a class="spai-bg-prepared" href="https://doi.org/10.1038/s41562-022-01359-x" target="_blank" rel="noreferrer noopener">published</a> in <em class="spai-bg-prepared">Nature Human Behaviour</em>.</p> <figure class="wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio spai-bg-prepared"> <div class="wp-block-embed__wrapper spai-bg-prepared"> <div class="entry-content-asset spai-bg-prepared"> <div class="embed-wrapper spai-bg-prepared"> <div class="inner spai-bg-prepared"><iframe class="spai-bg-prepared" title="The Go-Go's - We Got The Beat (Official Music Video)" src="https://www.youtube.com/embed/f55KlPe81Yw?feature=oembed" width="500" height="281" frameborder="0" allowfullscreen="allowfullscreen"></iframe></div> </div> </div> </div> </figure> <p class="spai-bg-prepared">We got the beat… well maybe some of us!</p> <p><!-- Start of tracking content syndication. Please do not remove this section as it allows us to keep track of republished articles --></p> <p><img id="cosmos-post-tracker" class="spai-bg-prepared" style="opacity: 0; height: 1px!important; width: 1px!important; border: 0!important; position: absolute!important; z-index: -1!important;" src="https://syndication.cosmosmagazine.com/?id=195164&amp;title=Keeping+to+the+beat+controlled+by+69+genes+%E2%80%93+not+just+our+feet" width="1" height="1" /></p> <p><!-- End of tracking content syndication --></p> <div id="contributors"> <p><em><a href="https://cosmosmagazine.com/science/biology/keeping-the-beat-genetics/" target="_blank" rel="noopener">This article</a> was originally published on <a href="https://cosmosmagazine.com" target="_blank" rel="noopener">Cosmos Magazine</a> and was written by <a href="https://cosmosmagazine.com/contributor/qamariya-nasrullah" target="_blank" rel="noopener">Qamariya Nasrullah</a>. Qamariya Nasrullah holds a PhD in evolutionary development from Monash University and an Honours degree in palaeontology from Flinders University.</em></p> <p><em>Image: Getty Images</em></p> </div>

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Genetic mutations slowly accumulated over a lifetime change blood production after 70 years of age

<p class="spai-bg-prepared">Ageing is likely caused by the gradual accumulation of molecular damage, or genetic mutations, in the cells of our bodies that occurs over a lifetime. But how this translates into the rapid deterioration in organ function that’s seen after the age of 70 has so far not been clear.</p> <p class="spai-bg-prepared">Now, scientists have discovered that the accumulation of genetic mutations in blood stem cells are likely responsible for the abrupt change in how <a class="spai-bg-prepared" href="https://cosmosmagazine.com/science/biology/why-do-we-have-blood/" target="_blank" rel="noreferrer noopener">blood</a> is produced in the body after 70 years of age.</p> <p class="spai-bg-prepared">The <a class="spai-bg-prepared" href="https://www.nature.com/articles/s41586-022-04786-y" target="_blank" rel="noreferrer noopener">new study</a>, published in <em class="spai-bg-prepared">Nature</em>, points to a change in the diversity of stem cells that produce blood cells as the reason why the prevalence of reduced cell regeneration capacity, <a class="spai-bg-prepared" href="https://www.frontiersin.org/articles/10.3389/fonc.2020.579075/full" target="_blank" rel="noreferrer noopener">cytopenia</a> (one or more blood cell types is lower than it should be), immune disfunction, and risk of blood cancer dramatically rises after 70.</p> <p class="spai-bg-prepared">“We’ve shown, for the first time, how steadily accumulating mutations throughout life lead to a catastrophic and inevitable change in blood cell populations after the age of 70,” says joint-senior author Dr Peter Campbell, head of the Cancer, Ageing and Somatic Mutation Program at the Wellcome Sanger Institute, UK.</p> <p class="spai-bg-prepared">“What is super exciting about this model is that it may well apply in other organ systems too.”</p> <p><strong>Blood cells are made in a process called haematopoiesis</strong></p> <p class="spai-bg-prepared">All of the cells in our blood – including red cells, white cells and platelets – develop in a process called haematopoiesis from haematopoietic stem cells in our bone marrow. These stem cells are what’s known as multipotent progenitor cells, which simply means that they can develop into more than one cell type.</p> <p class="spai-bg-prepared">Researchers were interested in better understanding how this process changes as we age, so they sequenced the entire genomes of 3,579 haematopoietic stem cells from a total of 10 people – ranging in age from newborn to 81 years.</p> <div class="newsletter-box spai-bg-prepared"> <div id="wpcf7-f6-p193434-o1" class="wpcf7 spai-bg-prepared" dir="ltr" lang="en-US" role="form"> <form class="wpcf7-form mailchimp-ext-0.5.61 spai-bg-prepared init" action="/science/mutations-change-blood-production/#wpcf7-f6-p193434-o1" method="post" novalidate="novalidate" data-status="init"> <p class="spai-bg-prepared" style="display: none !important;"><span class="wpcf7-form-control-wrap referer-page spai-bg-prepared"><input class="wpcf7-form-control wpcf7-text referer-page spai-bg-prepared" name="referer-page" type="hidden" value="https://www.google.com/" data-value="https://www.google.com/" aria-invalid="false" /></span></p> <p><!-- Chimpmail extension by Renzo Johnson --></form> </div> </div> <p class="spai-bg-prepared">Using this information, they were able to construct something similar to a family tree (<a class="spai-bg-prepared" href="https://www.nature.com/scitable/topicpage/reading-a-phylogenetic-tree-the-meaning-of-41956/#:~:text=A%20phylogenetic%20tree%2C%20also%20known,genes%20from%20a%20common%20ancestor." target="_blank" rel="noreferrer noopener">a phylogenetic tree</a>) for each stem cell, showing how the relationships between blood cells changes over the human lifespan.</p> <p class="spai-bg-prepared">They found that in adults under 65, blood cells were produced from between 20,000 and 200,000 different stem cells – each contributing roughly equal amounts to production.</p> <p class="spai-bg-prepared">But after 70 years of age they observed a dramatic decrease in the diversity of stem cells responsible for haematopoiesis in the bone marrow. In fact, only 12-18 independent expanded sets of stem cell clones accounted for 30-60% of cell production.</p> <p class="spai-bg-prepared">These highly active stem cells had outcompeted others and progressively expanded in numbers (clones) across that person’s life, and this expansion (called <a class="spai-bg-prepared" href="https://www.nature.com/articles/s41586-022-04785-z" target="_blank" rel="noreferrer noopener">clonal haematopoiesis</a>) was caused by a rare subset of mutations known as driver mutations that had occurred decades earlier.</p> <p class="spai-bg-prepared">“Our findings show that the diversity of blood stem cells is lost in older age due to positive selection of faster-growing clones with driver mutations. These clones ‘outcompete’ the slower growing ones,” explains lead researcher Dr Emily Mitchell, a haematology registrar at Addenbrooke’s Hospital,UK, and PhD student at the Wellcome Sanger Institute, US.</p> <p class="spai-bg-prepared">“In many cases this increased fitness at the stem cell level likely comes at a cost – their ability to produce functional mature blood cells is impaired, so explaining the observed age-related loss of function in the blood system.”</p> <p class="spai-bg-prepared">Which clones became the dominant stem cells varied between individuals, which explains why variation is seen in disease risk and other characteristics in older adults.</p> <p class="spai-bg-prepared">“Factors such as chronic inflammation, smoking, infection and chemotherapy cause earlier growth of clones with cancer-driving mutations. We predict that these factors also bring forward the decline in blood stem cell diversity associated with ageing,” says joint-senior author Dr Elisa Laurenti, assistant professor at the Wellcome-MRC Cambridge Stem Cell Institute, UK.</p> <p class="spai-bg-prepared">“It is possible that there are factors that might slow this process down, too,” she adds. “We now have the exciting task of figuring out how these newly discovered mutations affect blood function in the elderly, so we can learn how to minimise disease risk and promote healthy ageing.”</p> <p><!-- Start of tracking content syndication. Please do not remove this section as it allows us to keep track of republished articles --></p> <p><img id="cosmos-post-tracker" class="spai-bg-prepared" style="opacity: 0; height: 1px!important; width: 1px!important; border: 0!important; position: absolute!important; z-index: -1!important;" src="https://syndication.cosmosmagazine.com/?id=193434&amp;title=Genetic+mutations+slowly+accumulated+over+a+lifetime+change+blood+production+after+70+years+of+age" width="1" height="1" /></p> <p><!-- End of tracking content syndication --></p> <div id="contributors"> <p><em><a href="https://cosmosmagazine.com/science/mutations-change-blood-production/" target="_blank" rel="noopener">This article</a> was originally published on <a href="https://cosmosmagazine.com" target="_blank" rel="noopener">Cosmos Magazine</a> and was written by <a href="https://cosmosmagazine.com/contributor/imma-perfetto" target="_blank" rel="noopener">Imma Perfetto</a>. Imma Perfetto is a science writer at Cosmos. She has a Bachelor of Science with Honours in Science Communication from the University of Adelaide.</em></p> <p><em>Image: Getty Images</em></p> </div>

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Genetic discovery may help scientists reverse hearing loss

<p>Neuroscience researchers have found a master gene that controls the development of special sensory cells in the ears – potentially opening the door to reversing hearing loss.</p> <p>A team led by Jaime García-Añoveros of Northwestern University, US, established that a gene called Tbx2 controls the development of ear hair cells in mice. The findings of their study are <a href="https://www.nature.com/articles/s41586-022-04668-3" target="_blank" rel="noreferrer noopener">published today in <em>Nature</em></a><em>.</em></p> <p><strong>What are hair cells?</strong></p> <p>Hair cells are the sensory cells in our ears that detect sound and then transmit a message to our brains. They are so named because they have tiny hairlike structures called stereocilia.</p> <p>“The ear is a beautiful organ,” says García-Añoveros. “There is no other organ in a mammal where the cells are so precisely positioned.”</p> <p>Hair cells are found in a structure called the organ of Corti, in the cochlea in the inner ear. The organ of Corti sits on top of the basilar membrane.</p> <p>Sound waves are funnelled through our ear canal and cause the eardrum (also known as the tympanic membrane) and ossicles (tiny bones called the malleus, incus and stapes) to vibrate. The vibrations, or waves, are transmitted through fluid in the cochlea, causing the basilar membrane to move as well.</p> <p>When the basilar membrane moves, the stereocilia tilt, causing ion channels in the hair cell membrane to open. This stimulates the hair cell to release neurotransmitter chemicals, which will transmit the sound signal to the brain via the auditory nerve.</p> <figure class="wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio"> <div class="wp-block-embed__wrapper"> <div class="entry-content-asset"> <div class="embed-wrapper"> <div class="inner"><iframe title="2-Minute Neuroscience: The Cochlea" src="https://www.youtube.com/embed/WeQluId1hnQ?feature=oembed" width="500" height="281" frameborder="0" allowfullscreen="allowfullscreen"></iframe></div> </div> </div> </div> </figure> <h2> </h2> <p><strong>Hair cells and hearing loss</strong></p> <p>There are actually two types of hair cells: inner and outer. We need both types to hear effectively. The outer hair cells change their shape and amplify sound for the inner hair cells, which transmit the vibrations to the brain.</p> <div class="newsletter-box"> <div id="wpcf7-f6-p190195-o1" class="wpcf7" dir="ltr" lang="en-US" role="form"> </div> </div> <p>“It’s like a ballet,” says García-Añoveros. “The outers crouch and jump and lift the inners further into the ear.”</p> <p>Hair cells develop before we are born and do not typically divide to create new versions of themselves. As we age, our hair cells die, <a href="https://cosmosmagazine.com/health/hair-cell-loss-may-explain-hearing-loss/">leading to hearing loss</a>. Loss of outer hair cells is particularly common.</p> <p>According to the US Centers for Disease Control, about 8.5% of adults aged 55-64 in the US experience “disabling” hearing loss, with that number increasing to nearly 25% in people aged 65-74, and 50% in those 75 and older.</p> <p><strong>Could we one day reverse hearing loss?</strong></p> <p>Since hair cells don’t usually divide, we may be able to reverse hearing loss if we can reprogram stem cells or other cells in the ear to become hair cells to replace those that die.</p> <p>Scientists have already produced artificial hair cells, but until now didn’t know how to direct the cell to become an inner or an outer hair cell.</p> <p>The team at Northwestern discovered that a gene called Tbx2 controls the development of both inner and outer hair cells. If Tbx2 is “switched on” to produce the protein TBX2, the cell develops into an inner hair cell. If Tbx2 is “off”, it becomes an outer hair cell.</p> <p>“Our finding gives us the first clear cell switch to make one type versus the other,” García-Añoveros explains.</p> <p>The finding is a step towards learning how we can reprogram the cells that usually provide structural support for the hair cells to become inner or outer hair cells themselves – replacing dead hair cells and preventing or reversing hearing loss.</p> <p>“We can now figure out how to make specifically inner or outer hair cells and identify why the latter are more prone to dying,” García-Añoveros says. “We have overcome a major hurdle.”</p> <p><img id="cosmos-post-tracker" style="opacity: 0; height: 1px!important; width: 1px!important; border: 0!important; position: absolute!important; z-index: -1!important;" src="https://syndication.cosmosmagazine.com/?id=190195&amp;title=Genetic+discovery+may+help+scientists+reverse+hearing+loss" width="1" height="1" data-spai-target="src" data-spai-orig="" data-spai-exclude="nocdn" /></p> <div id="contributors"> <p><em><a href="https://cosmosmagazine.com/science/genetic-discovery-reverse-hearing-loss/" target="_blank" rel="noopener">This article</a> was originally published on <a href="https://cosmosmagazine.com" target="_blank" rel="noopener">Cosmos Magazine</a> and was written by <a href="https://cosmosmagazine.com/contributor/matilda-handlsey-davis" target="_blank" rel="noopener">Matilda Handsley-Davis</a>. Matilda is a science writer at Cosmos. She holds a Bachelor of Arts and a Bachelor of Science (Honours) from the University of Adelaide.</em></p> <p><em>Image: Getty Images</em></p> </div>

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Three reasons you haven’t caught Covid yet

<p dir="ltr">Most of us have been in close contact with someone who contracted Covid but never tested positive ourselves.</p> <p dir="ltr">It raises questions as to why you would not test positive yourself despite being in the same room as a positive case, sharing food and drink despite how infectious the virus is.</p> <p dir="ltr">There are three possible reasons as to why you still haven’t caught Covid, despite the situation leaving doctors stumped. </p> <p dir="ltr">Australian National University lecturer and epidemiologist Dr Katrina Roper helps explain the three main reasons why some don’t test positive. </p> <p dir="ltr"><strong>Common cold</strong></p> <p dir="ltr">Before Covid, we’d all be exposed to the common cold which would help build immunity against other viruses. </p> <p dir="ltr">“Having a prior infection to another cold virus can confer some protection to Covid, or other respiratory viruses,” Dr Roper told <a href="https://www.news.com.au/lifestyle/health/health-problems/a-doctor-explains-why-you-havent-caught-covid-yet/news-story/d57a08a08278abf27f43c29fcfe87196" target="_blank" rel="noopener">news.com.au</a>.</p> <p dir="ltr">”Exposure to other respiratory viruses can prime parts of the immune system, leading to better defence against infection by the SARS CoV-2 infection”.</p> <p dir="ltr">Research published in the Nature Communications journal in January 2022, confirmed the theory that being exposed to Covid won’t always cause an infection.</p> <p dir="ltr">“Being exposed to the SARS-CoV-2 virus doesn’t always result in infection, and we’ve been keen to understand why,” lead author Dr Rhia Kundu wrote.</p> <p dir="ltr">“We found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against COVID-19 infection.”</p> <p dir="ltr">Immunologist Professor Stuart Tangye insists that there’s also a possibility that you were infected with Covid but you didn’t know it. </p> <p dir="ltr"><strong>Your immune system</strong></p> <p dir="ltr">When it comes to avoiding Covid it could be that your immune system is pretty strong, or the vaccine worked better for you. </p> <p dir="ltr">Dr Roper however did point out that it could also all depend on the individuals’ circumstance - such as their age, weight and how healthy they are.</p> <p dir="ltr">She noted that even the healthiest of people could still have weakened immune systems - citing professional athletes who push themselves and in turn feel worse afterwards. </p> <p dir="ltr"><strong>The exposure</strong></p> <p dir="ltr">Again, everyone has been exposed differently to Covid and while some may have contracted it, you didn’t. </p> <p dir="ltr">The circumstances of where you are could be affected such as a large house but only two people living there, giving you ample space to stay away despite sharing the same areas.</p> <p dir="ltr"><strong>Genetics</strong></p> <p dir="ltr">Professor Tangye suggested a fourth reason as to why you haven’t contracted Covid despite your exposure.</p> <p dir="ltr">Put simply, your genetics. </p> <p dir="ltr">“There are going to be people who are less susceptible to viral infection because they have differences in their genes, such as genes that are important for viral entry into your cells,” he said.</p> <p dir="ltr"><em>Image: Shutterstock</em></p>

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“We really, really did it!”: Human genome finally completed

<p dir="ltr">Scientists say they have finally mapped the entire human genome, 20 years after it was first celebrated around the world.</p> <p dir="ltr">A team of international researchers have been able to fill in the gaps in the sequence that contains all of the genetic information humans need to function.</p> <p dir="ltr">The scientists worked together as part of the Telomere to Telomere (T2T) consortium and presented a gap-free sequence of the roughly three billion bases (or “letters”) in DNA.</p> <p dir="ltr">These letters, known as A, C, G and T, form pairs that are strung together to form genes and can include instructions for making proteins which are then used for everything from repairing tissue and helping our immune systems function to providing structure for our cells and allowing our bodies to move.</p> <p dir="ltr">The new research comes after the first draft of the human genome was announced in 2000, which was incomplete because technology to sequence DNA wasn’t able to read certain parts of it.</p> <p dir="ltr">These parts included really long, highly repetitive sequences of the letters which have been described as “junk DNA”.</p> <p dir="ltr">As technology evolved and the genome continued to be updated, about eight percent of the DNA in the genome was still unknown - until now.</p> <p dir="ltr">“Some of the genes that make us uniquely human were actually in this ‘dark matter of the genome’ and were totally missed,” Evan Eichler, a University of Washington researcher who was involved in the current research and the original Human Genome Project, told <em><a href="https://www.nzherald.co.nz/world/scientists-finally-finish-decoding-entire-human-genome/2YQLOXHMWP5TWJJ6HW24WH5QGA/" target="_blank" rel="noopener">NZ Herald</a></em>.</p> <p dir="ltr">“It took 20-plus years, but we finally got it done.”</p> <p dir="ltr">Many - including Eicher’s own students - thought the genome had been completed by now, making the latest achievement even more surprising.</p> <p dir="ltr">“I was teaching them, and they said, ‘Wait a minute. Isn’t this like the sixth time you guys have declared victory?’ I said, ‘No, this time we really, really did it!’”</p> <p><span id="docs-internal-guid-2005b113-7fff-3fcf-efca-0f8f8e295010"></span></p> <p dir="ltr">The research is so significant it even prompted Eichler to write his first ever tweet announcing it.</p> <blockquote class="twitter-tweet"> <p dir="ltr" lang="en">It only took a complete human genome for <a href="https://twitter.com/EichlerEE?ref_src=twsrc%5Etfw">@EichlerEE</a> actually make his first twitter post. I think this means we can expect more posts from him in the future as long as <a href="https://twitter.com/aphillippy?ref_src=twsrc%5Etfw">@aphillippy</a> <a href="https://twitter.com/sergeynurk?ref_src=twsrc%5Etfw">@sergeynurk</a> <a href="https://twitter.com/sergekoren?ref_src=twsrc%5Etfw">@sergekoren</a> <a href="https://twitter.com/ArangRhie?ref_src=twsrc%5Etfw">@ArangRhie</a> <a href="https://twitter.com/MikkoRautiaine3?ref_src=twsrc%5Etfw">@MikkoRautiaine3</a> finish some more genomes! <a href="https://t.co/aDSwBt6gW1">https://t.co/aDSwBt6gW1</a></p> <p>— Mitchell R. Vollger (@mrvollger) <a href="https://twitter.com/mrvollger/status/1509606815184547841?ref_src=twsrc%5Etfw">March 31, 2022</a></p></blockquote> <p dir="ltr">Karen Miga, another of the authors of the six studies released on Thursday, said having a complete picture of the genome would further the understanding of our evolution and pave the way for medical discoveries in areas such as ageing, cancer, and neurodegenerative conditions.</p> <p dir="ltr">“We’re just broadening our opportunities to understand human disease,” Miga said.</p> <p dir="ltr">Before now, Miga said the gaps in the map of the genome were “large and persistent” and in “pretty important regions”.</p> <p dir="ltr">The hugely collaborative work, including researchers from the University of California, the University of Washington, and the National Human Genome Research Institute, also corrects previous errors in the map.</p> <p dir="ltr">“This is a major improvement, I would say, of the Human Genome Project,” said geneticist Ting Wang, who wasn’t involved in the studies.</p> <p dir="ltr">It also turned out that these unknown stretches of DNA also contain some that play an important role in evolution and disease, and even some that are integral to making our brains larger than a chimp’s.</p> <p dir="ltr">Reading genes requires scientists to cut strands of DNA into pieces, which sequencing machines then read letter by letter. With the strands being anywhere from hundreds to thousands of letters long, scientists are then tasked with reordering the pieces so they are correct - a tough task when there are lots of repeating letters.</p> <p dir="ltr"><span id="docs-internal-guid-bcb131c9-7fff-607b-e482-d45983d9d97c"></span></p> <p dir="ltr">With technology now allowing for the genome to be complete, future research will look to map even more genomes and collect genes from both parents.</p> <p dir="ltr"><em>Image: Getty Images</em></p>

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Physical symptoms linked to genetic risk of depression

<p><span style="font-weight: 400;">People who experience physical symptoms such as chronic pain, fatigue and migraines are also more likely to have a higher genetic risk of clinical depression, according to a new study.</span></p> <p><span style="font-weight: 400;">Researchers from the University of Queensland collaborated with the QIMR Berghofer Medical Research Institute at the Royal Brisbane and Women’s Hospital to conduct a new study published in </span><em><a rel="noopener" href="https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2783096" target="_blank"><span style="font-weight: 400;">JAMA Psychiatry</span></a></em><span style="font-weight: 400;">.</span></p> <p><span style="font-weight: 400;">They analysed data from over 15,000 volunteers, who provided information about their mental health history, depression symptoms, and a DNA sample.</span></p> <p><span style="font-weight: 400;">The team found that participants who had a higher genetic risk of developing clinical depression were more likely to experience additional physical symptoms.</span></p> <p><span style="font-weight: 400;">Dr Enda Byrne, a senior research fellow in psychiatric genetics and one of the researchers involved, said the study aimed to improve understanding of the genetic risks of depression and how other symptoms can be used to aid diagnosis.</span></p> <p><img style="width: 500px; height:281.25px;" src="https://oversixtydev.blob.core.windows.net/media/7845012/depression1.jpg" alt="" data-udi="umb://media/e08ca3fc9f134a3c8fb3556dde363b83" /></p> <p><em><span style="font-weight: 400;">Dr Enda Byrnes, the senior author of the latest study on depression and genetic risk. Image: The University of Queensland</span></em></p> <p><span style="font-weight: 400;">“A large proportion of people with clinically-diagnosed depression present initially to doctors with physical symptoms that cause distress and can severely impact on people’s quality of life,” </span><a rel="noopener" href="https://www.scimex.org/newsfeed/genetic-risk-for-clinical-depression-linked-to-physical-symptoms" target="_blank"><span style="font-weight: 400;">he said</span></a><span style="font-weight: 400;">.</span></p> <p><span style="font-weight: 400;">“Our research aimed to better understand the biological basis of depression and found that assessing a broad range of symptoms was important.</span></p> <p><span style="font-weight: 400;">“We wanted to see how genetic risk factors based on clinical definitions of depression differed - from those based on a single question to those based on a doctor’s consultation about mental health problems.”</span></p> <p><strong>Genetic risks of depression, explained</strong></p> <p><span style="font-weight: 400;">Many different factors can contribute to the onset of depression, and there is strong evidence to suggest that genetics can affect the likelihood of developing the mental illness.</span></p> <p><span style="font-weight: 400;">Individuals can be predisposed to developing depression if someone in their family has been diagnosed. If a person’s biological parent has been diagnosed with clinical depression, their genetic risk of developing the illness sits at </span><a rel="noopener" href="https://www.blackdoginstitute.org.au/wp-content/uploads/2020/04/1-causesofdepression.pdf" target="_blank"><span style="font-weight: 400;">about 40 percent</span></a><span style="font-weight: 400;">, with the other 60 percent coming from factors in their environment such as stress and age.</span></p> <p><span style="font-weight: 400;">Previous studies have also examined the role genetics plays in depression, but Dr Byrne said it can be difficult to find genetic risk factors that are specific to clinical depression.</span></p> <p><span style="font-weight: 400;">“Previous genetic studies have included participants who report having seen a doctor for worries or tension - but who may not meet the ‘official’ criteria for a diagnosis of depression,” he said.</span></p> <p><span style="font-weight: 400;">The researchers also stressed the importance of using a large number of samples in order to identify the risk factors for clinical depression but not for other definitions of depression.</span></p> <p><span style="font-weight: 400;">“It is also linked to higher rates of somatic symptoms - that is, physical symptoms that cause distress and can severely impact on people’s quality of life,” Dr Byrne said.</span></p> <p><span style="font-weight: 400;">“Our results highlight the need for larger studies investigating the broad range of symptoms experienced by people with depression.”</span></p> <p><em><span style="font-weight: 400;">Image: Getty Images</span></em></p>

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Genetic link between alcoholism and Alzheimer’s risk discovered

<p><span style="font-weight: 400;">Scientists have found a genetic overlap between alcohol use disorder (AUD) and neurodegenerative disorders such as Alzheimer’s.</span></p> <p><span style="font-weight: 400;">In a </span><a rel="noopener" href="https://www.nature.com/articles/s41467-021-25392-y" target="_blank"><span style="font-weight: 400;">study</span></a><span style="font-weight: 400;"> published in </span><em><span style="font-weight: 400;">Nature Communications</span></em><span style="font-weight: 400;">, the researchers identified several genes associated with alcoholism, including two previously linked to neurodegenerative disorders.</span></p> <blockquote class="twitter-tweet"> <p dir="ltr">First of its kind study using multi-omics approach identifies large list of candidate genes associated with alcohol use disorder - study shows potential genetic link between <a href="https://twitter.com/hashtag/alcoholism?src=hash&amp;ref_src=twsrc%5Etfw">#alcoholism</a>, <a href="https://twitter.com/hashtag/Alzheimers?src=hash&amp;ref_src=twsrc%5Etfw">#Alzheimers</a> disease, &amp; other neurodegenerative disorders <a href="https://t.co/kzautcL6DN">https://t.co/kzautcL6DN</a><a href="https://twitter.com/hashtag/genetics?src=hash&amp;ref_src=twsrc%5Etfw">#genetics</a> <a href="https://t.co/nUNbvYf2L8">pic.twitter.com/nUNbvYf2L8</a></p> — Mount Sinai Genetics (@SinaiGenetics) <a href="https://twitter.com/SinaiGenetics/status/1428699409475309571?ref_src=twsrc%5Etfw">August 20, 2021</a></blockquote> <p><span style="font-weight: 400;">“Several of these genes are also associated with neurodegenerative disorders - an intriguing connection because of alcohol’s ability to prematurely age the brain,” David Goldman, a neurogenetics researcher at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) told </span><span style="font-weight: 400;">The Scientist</span><span style="font-weight: 400;">.</span></p> <p><span style="font-weight: 400;">The scientists compared the genetic data of about 700,000 families involved in the NIAAA’s </span><a rel="noopener" href="https://www.niaaa.nih.gov/research/major-initiatives/collaborative-studies-genetics-alcoholism-coga-study" target="_blank"><span style="font-weight: 400;">Collaborative Studies on the Genetics of Alcoholism</span></a><span style="font-weight: 400;"> (COGA), as well as data from the </span><a rel="noopener" href="https://www.ukbiobank.ac.uk/enable-your-research/approved-research/alcohol-consumption-and-brain-health" target="_blank"><span style="font-weight: 400;">UK Biobank</span></a><span style="font-weight: 400;">, against analyses of adult and foetal brains to determine which genes were silenced or expressed.</span></p> <p><span style="font-weight: 400;">Though the study did identify many genes associated with alcohol use, the team focused on the two genes linked to neurodegenerative disorders: </span><em><span style="font-weight: 400;">SPI1</span></em><span style="font-weight: 400;"> and </span><em><span style="font-weight: 400;">MAPT</span></em><span style="font-weight: 400;">. </span></p> <p><em><span style="font-weight: 400;">SPI1</span></em><span style="font-weight: 400;"> produces a protein that controls the activity of immune cells, while </span><em><span style="font-weight: 400;">MAPT</span></em><span style="font-weight: 400;"> produces a protein found throughout the nervous system called tau.</span></p> <p><strong><em>SPI1</em> linked to Alzheimer’s</strong></p> <p><a rel="noopener" href="https://molecularneurodegeneration.biomedcentral.com/articles/10.1186/s13024-018-0277-1" target="_blank"><span style="font-weight: 400;">Previous research</span></a><span style="font-weight: 400;"> has shown that </span><em><span style="font-weight: 400;">SPI1</span></em><span style="font-weight: 400;"> influenced the likelihood of a person developing Alzheimer’s disease, with some theorising that it influences the activity of microglia, immune cells that are found in the brain.</span></p> <p><span style="font-weight: 400;">In a </span><a rel="noopener" href="https://www.nature.com/articles/s41398-019-0384-y" target="_blank"><span style="font-weight: 400;">study</span></a><span style="font-weight: 400;"> from two years ago, Manav Kapoor, a neuroscientist and geneticist at the Icahn School of Medicine at Mount Sinai and the new paper’s first author, and his team found evidence that people with AUD might have an overactive immune system - and this new paper could help explain their previous findings.</span></p> <p><span style="font-weight: 400;">The new study also found an association between the </span><em><span style="font-weight: 400;">SPI1</span></em><span style="font-weight: 400;"> gene and both heavy drinking and a diagnosis of AUD.</span></p> <p><span style="font-weight: 400;">Though alcoholism is already associated with immune dysfunction, the team found that expression of the </span><em><span style="font-weight: 400;">SPI1</span></em><span style="font-weight: 400;"> gene was higher in some foetal brains.</span></p> <p><span style="font-weight: 400;">Kapoor says this finding suggests that those genetically predisposed to AUD and heavy drinking are also predisposed to developing an overactive immune system.</span></p> <p><span style="font-weight: 400;">If this is the case, when people with particular versions of the gene drink heavily, Kapoor suggests that their immune systems could become overactivated and cause brain immune cells to alter connections between neurons.</span></p> <p><span style="font-weight: 400;">Kapoor bases this theory on a previous </span><a rel="noopener" href="https://stke.sciencemag.org/content/13/650/eaba5754" target="_blank"><span style="font-weight: 400;">study</span></a><span style="font-weight: 400;"> in mice that found that binge drinking activated brain immune cells, which selectively pruned certain synapses and caused the animals to display anxiety-like behaviours.</span></p> <p><span style="font-weight: 400;">The activation of these brain immune cells could result in the pruning of connections to neurons that produce dopamine - the chemical behind the “reward” feeling we get after drinking alcohol.</span></p> <p><span style="font-weight: 400;">As a result, people with certain versions of </span><em><span style="font-weight: 400;">SPI1</span></em><span style="font-weight: 400;"> who start drinking regularly would “have to drink more and more to get the same level of reward”, Kapoor says.</span></p> <p><span style="font-weight: 400;">“And their immune system will get more activated”, pruning more synapses.</span></p> <p><span style="font-weight: 400;">“It will become a vicious cycle,” Kapoor says.</span></p> <p><span style="font-weight: 400;">As for </span><em><span style="font-weight: 400;">MAPT</span></em><span style="font-weight: 400;">, the gene isn’t associated with AUD, but is associated with consuming more drinks per week.</span></p> <p><span style="font-weight: 400;">The tau protein it produces is thought to play a major role in neurodegenerative disorders including Alzheimer’s, Parkinson’s, frontotemporal dementia, and supranuclear palsy.</span></p> <p><span style="font-weight: 400;">However, it is still unclear how tau may factor into the consumption of alcohol.</span></p> <p><strong>Why this matters</strong></p> <p><span style="font-weight: 400;">Joel Gelernter, a geneticist and neurobiologist at Yale University School of Medicine, who was not involved in the study, says the study is “a really necessary step in unravelling the biology of alcohol intake and alcohol use disorder”.</span></p> <p><span style="font-weight: 400;">Kapoor says this work could benefit people in a few ways.</span></p> <p><span style="font-weight: 400;">First, he believes that drugs currently in development to treat neurodegenerative disorders could be repurposed to help people in reducing or stopping drinking.</span></p> <p><span style="font-weight: 400;">Second, it could be a way of reducing a person’s risk for neurodegenerative disorders.</span></p> <p><span style="font-weight: 400;">“If we can identify some group of people that are more at risk of Alzheimer’s disease, we can ask them to reduce their drinking,” he says.</span></p> <p><span style="font-weight: 400;">“That might be beneficial to them.”</span></p> <p><em><span style="font-weight: 400;">Image: Getty Images</span></em></p>

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A genetic mutation makes some people need less sleep

<p><span style="font-weight: 400;">Though most of us feel the consequences of missing out on a full night’s sleep, a lucky few don’t - thanks to a rare genetic mutation.</span></p> <p><span style="font-weight: 400;">According to a study published in </span><em><a rel="noopener" href="https://www.cell.com/neuron/fulltext/S0896-6273(19)30652-X" target="_blank"><span style="font-weight: 400;">Neuron</span></a></em><span style="font-weight: 400;">, some people who can function normally on six hours of sleep carry an altered version of a particular gene, making it the second to be associated with short sleep.</span></p> <p><span style="font-weight: 400;">In their previous research in </span><a rel="noopener" href="https://science.sciencemag.org/content/325/5942/866" target="_blank"><span style="font-weight: 400;">2009</span></a><span style="font-weight: 400;">, the team found a mother and daughter - who felt rested after about six hours of sleep at night - both had a mutation in a gene called </span><em><span style="font-weight: 400;">DEC2</span></em><span style="font-weight: 400;">.</span></p> <p><span style="font-weight: 400;">The </span><em><span style="font-weight: 400;">DEC2</span></em><span style="font-weight: 400;"> gene codes for a protein that stops other genes from expressing. One of these genes that the protein inhibits controls a hormone called orexin, which is known to regulate wakefulness.</span></p> <p><span style="font-weight: 400;">In the follow-up study, the scientists studied another family of naturally short sleepers and have identified another mutation, which they estimate about four in every 100,000 people have.</span></p> <p><span style="font-weight: 400;">The scientists engineered mice to have the same mutation and found that they slept, on average, one hour less per day than control mice without the mutation.</span></p> <p><span style="font-weight: 400;">For the family of humans with the mutation, they slept an average of two hours less per day than those without the mutation.</span></p> <p><span style="font-weight: 400;">The mutated gene, called </span><em><span style="font-weight: 400;">ADRB1</span></em><span style="font-weight: 400;">, encodes a receptor for a neural signalling molecule called noradrenaline.</span></p> <p><span style="font-weight: 400;">In mouse brains, the cells that had this receptor were active while they were awake and quiet during deep sleep, according to the researchers.</span></p> <p><span style="font-weight: 400;">They propose that the mutation makes these neurons more active, which could explain why its human carriers sleep for shorter periods of time.</span></p> <p><span style="font-weight: 400;">Though this research has been conducted on small groups, it could pave the way for the development of drugs that target these kinds of mutations or help those with sleeping disorders feel better while getting little sleep.</span></p>

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Can COVID vaccines affect my genetic code?

<p>The Pfizer and Moderna vaccines are set to become the mainstay of Australia’s COVID-19 vaccine rollout as the year progresses, according to the latest government projections <a href="https://www.abc.net.au/news/2021-06-23/gov-projects-little-need-for-astrazeneca-after-october-covid19/100239442">released this week</a>.</p> <p><a href="https://www.health.gov.au/sites/default/files/documents/2021/06/covid-19-vaccination-covid-vaccination-allocations-horizons.pdf">From September</a>, up to an average 1.3m doses of the Pfizer vaccine plus another 125,000 doses of the yet-to-be approved Moderna vaccine are expected to be available per week. These figures are set to rise from October, as use of the AstraZeneca vaccine drops.</p> <p>Both the Pfizer and Moderna vaccines are mRNA vaccines, which contain tiny fragments of the genetic material known as “messenger ribonucleic acid”. And if social media is anything to go by, <a href="https://twitter.com/AJ19803/status/1334476726022385666">some people</a> are concerned these vaccines can affect their genetic code.</p> <p>Here’s why the chances of that happening are next to zero and some pointers to how the myth came about.</p> <p><strong>Remind me, how do mRNA vaccines work?</strong></p> <p>The technology used in the Pfizer and Moderna vaccines is a way of giving your cells temporary instructions to make the <a href="https://theconversation.com/revealed-the-protein-spike-that-lets-the-2019-ncov-coronavirus-pierce-and-invade-human-cells-132183">coronavirus spike protein</a>. This protein is found on the surface of SARS-CoV-2, the virus that causes COVID-19. The vaccines teach your immune system to protect you if you ever encounter the virus.</p> <p>The mRNA in the vaccine is taken up by the cells in your body, ending up in the liquid inside each cell known as the cytoplasm. Our cells naturally make <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941114/">thousands of our own mRNAs</a> all the time (to code for a range of other proteins). So the vaccine mRNA is just another one. Once the vaccine mRNA is in the cytoplasm it’s used to make the SARS-CoV-2 spike protein.</p> <p>The vaccine mRNA is <a href="https://theconversation.com/what-is-mrna-the-messenger-molecule-thats-been-in-every-living-cell-for-billions-of-years-is-the-key-ingredient-in-some-covid-19-vaccines-158511">short-lived</a> and is rapidly broken down after it’s done its job, as happens with all your other mRNA.</p> <p><a rel="noopener" href="https://images.theconversation.com/files/408058/original/file-20210624-13-1w14e5y.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip" target="_blank"><img src="https://images.theconversation.com/files/408058/original/file-20210624-13-1w14e5y.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="Typical mammalian cell, showing different parts, such as nucleus and cytoplasm" /></a></p> <p><span class="caption">Vaccine mRNA is in the cytoplasm and once it’s done its job, it’s broken down.</span> </p> <p><strong>Here’s why the mRNA can’t insert into your genetic code</strong></p> <p> </p> <p>Your genetic code is made up of a different, but related, molecule to the vaccine mRNA, known as DNA, or deoxyribonucleic acid. And mRNA can’t insert itself into your DNA for two reasons.</p> <p>One, both molecules have a different chemistry. If mRNAs could routinely insert themselves into your DNA at random, this would play havoc with how you produce proteins. It would also scramble your genome, which is passed on to future cells and generations. Life forms that do this would not survive. That’s why life has evolved for this <em>not</em> to happen.</p> <p>The second reason is vaccine mRNA and DNA are in two different parts of the cell. Our DNA stays in the nucleus. But vaccine mRNA goes straight to the cytoplasm, never entering the nucleus. There are no transporter molecules we know of that carry mRNA into the nucleus.</p> <p><strong>But aren’t there some exceptions?</strong></p> <p>There are some extremely rare exceptions. One is where genetic elements, known as <a href="https://www.nature.com/scitable/topicpage/transposons-the-jumping-genes-518/">retro-transposons</a>, hijack cellular mRNA, convert it into DNA and insert that DNA back into your genetic material.</p> <p>This has occurred sporadically <a href="https://www.nature.com/articles/nrg2640">throughout evolution</a>, producing some ancient copies of mRNAs scattered throughout our genome, to form so-called <a href="https://www.nature.com/articles/s41576-019-0196-1">pseudogenes</a>.</p> <p>Some <a href="https://www.genome.gov/genetics-glossary/Retrovirus">retroviruses</a>, such as HIV, also insert their RNA into our DNA, using similar methods to retro-transposons.</p> <p>However, there is a vanishingly small chance of a naturally occurring retro-transposon becoming active in a cell that has just received a mRNA vaccine. There’s also a vanishingly small chance of being infected with HIV at precisely the same time as receiving the mRNA vaccine.</p> <p><a href="https://images.theconversation.com/files/408059/original/file-20210624-29-gcexgw.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/408059/original/file-20210624-29-gcexgw.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="Blood sample labelled with HIV - Test" /></a></p> <p><span class="caption">There’s a vanishingly small chance of being infected with HIV at precisely the same time as having an mRNA vaccine.</span> </p> <p>Even if a retro-transposon were to become active or a virus such as HIV were present, the chances of it finding the COVID vaccine mRNA, among the tens of thousands of natural mRNAs, is extremely unlikely. That’s because vaccine mRNA is degraded within <a href="https://pubmed.ncbi.nlm.nih.gov/18797453/">several hours</a> of entering the body.</p> <p>Even if vaccine mRNA did become a pseudogene, it would not produce the SARS-CoV-2 virus, but just one of the viral products, the harmless spike protein.</p> <p><strong>How do we actually know this?</strong></p> <p> </p> <p>We know of no studies looking for vaccine mRNA in the DNA of people who have been vaccinated. There is no scientific basis on which to suspect this insertion has happened.</p> <p>However, if these studies were to be carried out, they should be relatively straightforward. That’s because we can now <a href="https://cellandbioscience.biomedcentral.com/articles/10.1186/s13578-019-0314-y">sequence DNA in single cells</a>.</p> <p>But in reality, it will be very hard to ever satisfy a naysayer who is convinced this genome insertion happens; they can always argue scientists need to look deeper, harder, in different people and in different cells. At some point this argument will need to be laid to rest.</p> <p><strong>So how did this myth come about?</strong></p> <p><a href="https://doi.org/10.1073/pnas.2105968118">One study</a> reported evidence for coronavirus RNA integrating into the human genome in cells grown in the lab that had been infected with SARS-CoV-2.</p> <p>However, that paper did not look at the mRNA vaccine, lacked critical controls and <a href="https://www.biorxiv.org/content/10.1101/2021.03.05.434119v1">has</a> <a rel="noopener" href="https://doi.org/10.1128/JVI.00294-21" target="_blank">since been discredited</a>.</p> <p>These types of studies also need to be seen in context of the public’s wariness of genetic technology more broadly. This includes <a rel="noopener" href="https://www.nature.com/articles/nbt1099_941d" target="_blank">the public’s concerns</a> about genetically modified organisms (GMOs), for instance, over the past 20 years or so.</p> <p>But GMOs are different to the mRNA technology used to make COVID vaccines. Unlike GMOs, which are produced by inserting DNA into the genome, vaccine mRNA will not be in our genes or passed to the next generation. It’s broken down very quickly.</p> <p>In reality, mRNA technology has <a href="https://theconversation.com/3-mrna-vaccines-researchers-are-working-on-that-arent-covid-157858">all sorts of</a> <a href="https://www.wired.co.uk/article/mrna-vaccine-revolution-katalin-kariko">applications</a>, beyond vaccines, including biosecurity and sustainable agriculture. So it would be a pity for these efforts to be held back by misinformation.</p> <p> </p> <p><span><a href="https://theconversation.com/profiles/archa-fox-1153308">Archa Fox</a>, Associate Professor and ARC Future Fellow, <em><a href="https://theconversation.com/institutions/the-university-of-western-australia-1067">The University of Western Australia</a></em>; <a href="https://theconversation.com/profiles/jen-martin-17007">Jen Martin</a>, Leader, Science Communication Teaching Program, <em><a href="https://theconversation.com/institutions/the-university-of-melbourne-722">The University of Melbourne</a></em>, and <a href="https://theconversation.com/profiles/traude-beilharz-1240711">Traude Beilharz</a>, Assoc Professor ARC Future Fellow, Biochemistry &amp; Molecular Biology, Monash Biomedicine Discovery Institute, <em><a href="https://theconversation.com/institutions/monash-university-1065">Monash University</a></em></span></p> <p>This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a rel="noopener" href="https://theconversation.com/can-the-pfizer-or-moderna-mrna-vaccines-affect-my-genetic-code-162590" target="_blank">original article</a>.</p>

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Why are more men diagnosed with schizophrenia?

<p><span style="font-weight: 400;">New research has found a link between the genetic differences in men and women and their likelihood of developing certain psychotic and mood disorders.</span></p> <p><span style="font-weight: 400;">In a study </span><a href="https://www.biologicalpsychiatryjournal.com/article/S0006-3223(21)01139-2/fulltext"><span style="font-weight: 400;">recently published</span></a><span style="font-weight: 400;"> in </span><em><span style="font-weight: 400;">Biological Psychiatry</span></em><span style="font-weight: 400;">, researchers looked at the underlying genetic differences between the sexes for the reason why bipolar disorder, schizophrenia, and depression affect the two sexes in different ways and at different rates.</span></p> <p><span style="font-weight: 400;">After examining the genomes of 85,735 people with schizophrenia, bipolar disorder, or depression, and 109,946 people without any of those conditions, the researchers found almost a dozen single nucleotide polymorphisms (SNPs) that differed between men and women diagnosed with one of the three disorders.</span></p> <p><strong>What are the impacts of SNPs?</strong></p> <p><span style="font-weight: 400;">The four nucleotides - Adenine, Thymine, Cytosine, and Guanine - that are used to make DNA are compared in particular orders to make specific proteins.</span></p> <p><span style="font-weight: 400;">SNPs are a kind of mutation where a single nucleotide - either A, G, T, or C - is swapped for another in a specific spot in the genome. These substitutions can affect our risk of getting certain diseases. </span></p> <p><span style="font-weight: 400;">In the study of mental disorders in the different sexes, the team found that these mutations would have different impacts on the different sexes. Some SNPs were only linked to disease in one sex, while others decreased the likelihood of the disorder occurring in one sex but increased it in the other.</span></p> <p><span style="font-weight: 400;">The researchers also found that these mutations occurred in genes that are linked to vascular, immune, and neuronal development pathways, suggesting cardiovascular and neurological health are affected by each other in some way.</span></p> <p><span style="font-weight: 400;">“We found a SNP in the </span><span style="font-weight: 400;">IDO2</span><span style="font-weight: 400;"> gene,” Jill Goldstein, a clinical neuroscientist at Harvard Medical School and the senior author of the study, told </span><a href="https://www.the-scientist.com/news-opinion/genetic-variants-tied-to-sex-differences-in-psychiatric-disorders-68624"><span style="font-weight: 400;">The Scientist</span></a><span style="font-weight: 400;">. </span></p> <p><span style="font-weight: 400;">This particular gene is associated with immune tolerance in humans, meaning it helps suppress the immune system so it doesn’t attack bodily tissues and other substances. The gene is also linked to and has different effects on different disorders.</span></p> <p><span style="font-weight: 400;">“The SNP [in the </span><span style="font-weight: 400;">IDO2</span><span style="font-weight: 400;"> gene] increased the risk of bipolar disorder in women and decreased the risk in men, but it also decreased the risk of major depression and schizophrenia,” she said. “With that same genetic SNP, we found a lower risk of depression and schizophrenia in women, but a higher risk in the men.</span></p> <p><span style="font-weight: 400;">“And what was even more exciting was that the pathways that were implicated - vascular pathways and immune pathways - fit with what has been found and mapped by neurobiology,” Goldstein said.</span></p> <p><span style="font-weight: 400;">In their studies of the shared abnormal changes between the brain and heart, Goldstein and her team found schizophrenia has a high comorbidity with cardiovascular disease.</span></p> <p><span style="font-weight: 400;">“I was thrilled to see we actually found these genes with shared sex differences in areas that we’ve been studying,” she said.</span></p> <p><strong>Why this matters</strong></p> <p><span style="font-weight: 400;">Though these differences are small, they can have implications for how treatment can be tailored to different patients.</span></p> <p><span style="font-weight: 400;">Gendered differences in the presentation and effectiveness of treatments have been previously identified in other diseases including cardiovascular disease and lung cancer.</span></p> <p><span style="font-weight: 400;">“There are real-life consequences if we do not develop sex-dependent therapeutics, and I think it is critical for precision medicine,” she said.</span></p>

Mind

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5 traits you didn’t know you inherit from mum (and 4 you inherit from dad)

<p>Do you have your mum’s button nose? Did your dad pass on the curse of sneezing in bright sunlight? And where did your baby’s red, curly hair come from when there hasn’t been a redhead in your family for generations? These questions may sound simple but the answers get complicated fast. Why? Because the science of genetic inheritance is complicated, says genetic counsellor, Dawn Allain. “It’s nearly impossible to tease out exactly where each of your traits came from,” she explains. “Most traits are influenced by many different genes and you inherit some from each parent.” Plus, there’s the influence your environment plays; just because you have a gene for a certain trait doesn’t always mean you’ll end up with it, she adds.</p> <p><strong>How you inherit traits</strong></p> <p>Still, it’s fun to ask those questions and while there aren’t many detailed answers, there are a few basic things genetics can tell you about traits you inherit from your mum and those you got from our dad, Allain says. But first, you need to know how inheritance works.</p> <p>“There are three main ways you can inherit traits from your parents,” she explains. First is through a dominant gene – if you inherit a dominant gene you will develop that trait. Take eye colour, for example. If either of your parents have brown eyes, you likely will have brown eyes as this is a dominant trait. Second is through a recessive gene – both parents have to have the recessive gene for you to have that trait. For instance, if you have blue eyes then both of your parents must carry a gene for blue eyes, even if their eye colour isn’t blue. Lastly, there are X-linked traits which are found only on the X chromosome and are passed on through the mother.</p> <p><strong>Your ability to lose weight</strong></p> <p>There are two types of fat in your body: ‘good’ brown fat, which increases your metabolism and helps you maintain a healthy weight, and ‘bad’ white fat, which can cause obesity and disease if you have too much of it. Everyone has some of each type but how much brown fat you have – and therefore how high your metabolism is – may be inherited from your mum, according to a study published in Nature Communications. Another trait you get from your mum is your intelligence.</p> <p><strong>How easily you gain weight</strong></p> <p>However, while mum may be helping you out with the brown fat, you can blame your dad for your white fat, the Nature Communications study found. How much fat you store, particularly around your organs may be partly determined by genes passed down from your father, the researchers said. Genetics aren’t destiny when it comes to your weight, your lifestyle choices play an even bigger part.</p> <p><strong>Your ability to focus</strong></p> <p>If your mother has lower levels of serotonin, a brain chemical linked to mood, then you’re more likely to develop attention-deficit hyperactivity disorder later in life, according to a study published in JAMA Psychiatry. The genes, passed down from mum to kid, that impact serotonin production also seem to influence your ability to focus. Sound like you?</p> <p><strong>If you hit puberty early</strong></p> <p>Puberty, and all the fun milestones that come along with it, like acne, cracking voices, or getting your period while wearing white shorts, is a rite of passage many children go through on their way to becoming an adult. Both parents’ genetics play a part in determining when exactly you start the big change but if you started puberty early– before age eight in girls and nine in boys – that may be due to a gene you inherit from your father, according to a study published in the New England Journal of Medicine. Specifically, they identified that a genetic mutation leads to a type of premature puberty, meaning that if you have it, you’ll have to deal with all that stuff before any of your friends.</p> <p><strong>Your laugh lines</strong></p> <p>How well you age and how much you show it is determined on a cellular level by the accumulation of damage over your lifetime to your mitochondrial DNA – genes you only get from your mum. Environmental factors like sun exposure, smoking, and an unhealthy diet can cause mtDNA damage but some of the damage can be inherited from your mother, according to a study published in Nature. The more mtDNA with mutations you inherit from your mother, the faster you age and the more it will show in traits like wrinkles and grey hair.</p> <p><strong>Your mood</strong></p> <p>Mothers can influence your mood in many ways and it’s not just by grounding you or serving broccoli three times a week. The structure of the part of the brain known as the corticolimbic system, which controls emotional regulation and plays a role in mood disorders like depression, is more likely to be passed down from mothers to daughters than from mothers to sons or from fathers to children of either gender, according to a study published in The Journal of Neuroscience. This may mean that daughters at least partly inherit their mood from their mothers.</p> <p><strong>The genders of your children</strong></p> <p>Obviously the genes from you and your spouse determine the gender of your children. But did you know that which gender genes you pass on may be inherited from your father? This is how it works: a man with many brothers is more likely to have sons, while a man with many sisters is more likely to have daughters, according to a study published in Evolutionary Biology.</p> <p><strong>Your memory</strong></p> <p>It’s been known for some time that a family history of Alzheimer’s disease significantly increases the risk for developing the illness, but a new study, published in Biological Psychiatry, found that the genetic risk primarily comes from your mother. Alzheimer’s disease is the most common cause of dementia later in life, affecting nearly 459,000 Australians, so it’s important to know what factors increase your risk – including your mother’s medical history – so you can start taking steps to protect your brain health now, the researchers noted. Medical history is only one of the questions you should ask your parents before it’s too late.</p> <p><strong>Your fertility</strong></p> <p>A woman’s fertility may be impacted by a gene she inherited from her father, according to a study published in Science. In a normal egg cell, a part of the cell called the centrioles is eliminated as part of the natural development process. However, if the centrioles aren’t eliminated – often due to a genetic dysfunction, passed on by her dad – then the woman is sterile, researchers explained.</p> <p><strong>Your hairline?</strong></p> <p>You may have heard that how and when a man loses his hair is due to an inherited trait from his mum’s side. However, a study, published in PLoS Genetics, of over 55,000 men has proved this to be a myth. Researchers found 287 independent genetic signals that were linked to male-patterned hair loss and while 40 were only found on the X chromosome, meaning they were inherited on the maternal side, the rest were scattered throughout DNA inherited from both patterns. Interestingly, some genes associated with hair loss also seem to be associated with an increased risk for heart disease in men. While some traits are inherited, others are learned.</p> <p><em>Written by </em><strong>Charlotte Hilton</strong><em>. This article first appeared on </em><a href="https://www.readersdigest.com.au/culture/5-traits-you-didnt-know-you-inherit-from-mum-and-4-you-inherit-from-dad?pages=1"><em>Reader’s Digest</em></a><em>. For more of what you love from the world’s best-loved magazine, </em><a href="http://readersdigest.com.au/subscribe"><em>here’s our best subscription offer</em></a><em>.</em></p>

Relationships

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Genetic secrets of almost 2,700 cancers unveiled by landmark international project

<p>Scientists have revealed the detailed genetic makeup of thousands of cancer samples, yielding new insights into the genes that drive the many and varied forms of the disease.</p> <p>The results, <a href="https://www.nature.com/collections/pcawg/">published in a landmark collection of research papers in the journal Nature</a> interpret the complete DNA sequences, or cancer genomes, of 2,658 cancer samples. This will further our understanding of the crucial “driver” mutations that underpin cancer development and offer potential as targets for treatments such as chemotherapy.</p> <p>It is the work of some 700 scientists around the world, as part of an international project called the <a href="https://dcc.icgc.org/pcawg">Pan-Cancer Analysis of Whole Genomes</a>.</p> <p>The hallmark of a cancer cell is its unregulated growth. The mechanism that allows these cells to escape normal cellular growth regulation involves the introduction of mutations into the cancer cell’s DNA. The collection of mutations present in a particular cancer genome is thus known as that cancer’s “mutation signature”.</p> <p>Each advance in our capacity to accurately and completely sequence whole cancer genomes, and to analyse the sequence data, has enabled a more in-depth analysis of these mutation signatures. Each step forward has revealed further diversity in the mutation processes that underlie the development and progression of cancer.</p> <p><strong>Diverse mutations</strong></p> <p>It is seven years since the <a href="https://theconversation.com/cancer-signatures-offer-hope-for-treatment-and-prevention-17045">previous landmark advance in this field</a>. Back in 2013, researchers reported on the genetic makeup of 7,042 cancers of 30 different types, and identified 20 distinct mutational signatures.</p> <p>Today’s reports involve fewer cancers, but an increase in the number of cancer types to 38. But this latest advance is not really about numbers.</p> <p>The real step forward is in our understanding of the diversity of DNA mutations and mutation signatures within cancer genomes. This is primarily the result of improved methods for analysing the DNA sequence data, compared with the state of the art in 2013.</p> <p>As a result, important DNA sequence alterations that could not be detected in previous work have now been described. Each contributes important new details about each cancer genome.</p> <p>Until recently, cancer DNA mutation analyses had been focused on small alterations in “coding regions” of DNA - the roughly 1% of DNA that is responsible for making proteins. The new analyses reported today have identified non-coding driver mutations – some of them large structural mutations that can be as big as entire chromosomes.</p> <p>These new analytical capabilities have enabled the identification of 97 mutation signatures, five times more than previously known. The improved detail boosts our understanding of the diversity of cancer genomes. It also provides important new information about the order in which these mutations accumulate during cancer development.</p> <p>However, there is good evidence to suggest that more work is still required to characterise the full spectrum of cancer DNA mutations. It is anticipated that all cancers will have at least one, and perhaps as many as five, driver DNA mutations. Despite the extensive array of analytical approaches described in these new reports, the researchers were still unable to identify any driver mutations in 5% of the cancers in their study.</p> <p>The research has also shown that similar mutation signatures are present in cancers that arise in different tissues. This has implications for cancer treatment. For example, a drug successfully used to treat a breast cancer may be as effective for treating a pancreatic cancer if the two cancers share the same mutation signature.</p> <p>These data will greatly advance our ability to identify cancers with the same or similar origins via their mutation signature. It has enormous implications for diversifying the current suite of drugs available for gene-targeted cancer treatment.</p> <p>But, perhaps more significantly, it also offers the opportunity to expand our strategies for preventing cancer before it starts.</p> <p><em>Written by Melissa Southey. Republished with permission of </em><a href="https://theconversation.com/genetic-secrets-of-almost-2-700-cancers-unveiled-by-landmark-international-project-131197"><em>The Conversation.</em></a></p>

Beauty & Style

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Genetics reveal that Antarctica was once too cold for penguins

<p>Emperor penguins are truly remarkable birds – they thrive in the coldest environment on Earth and live year-round on the ice. Breeding colonies congregate on sea ice during the Antarctic winter and must withstand temperatures that regularly drop below -30C.</p> <p>In fact, emperor penguins are so adapted to cold conditions that they become heat stressed when temperatures climb above 0C. Emperor penguins are therefore particularly threatened by climate change, and their numbers are expected to <a href="http://www.nature.com/nclimate/journal/v4/n8/full/nclimate2280.html">decline</a> in the coming decades.</p> <p>However a <a href="http://dx.doi.org/10.1111/gcb.12882">new study</a>, published today in Global Change Biology, shows that it was once too cold even for emperor penguins.</p> <p><strong>Penguins past and present</strong></p> <p>In our study of how changing climate has affected emperor penguins over the past 30,000 years we found that, during the last ice age, emperor penguins were roughly seven times less common than today. What’s more, it appears that only three populations survived the last ice age. The Ross Sea was a refuge for one of these populations.</p> <p>In the first continental-scale genetic study of emperor penguins, we examined genetic diversity of penguins modern and ancient to find out how they’re related. We collected genetic samples from eight breeding colonies – no easy feat given that emperor penguins live in some of the remotest places on Earth in conditions that would send most people running for a roaring fire and a hot cup of tea.</p> <p><a href="https://images.theconversation.com/files/72856/original/image-20150224-32209-815vrd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/72856/original/image-20150224-32209-815vrd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="" /></a> <span class="caption">A rookery near Mawson station.</span> <span class="attribution"><span class="source">Chris Wilson/Australian Antarctic Division</span>, <span class="license">Author provided</span></span></p> <p>Reaching the colonies involved weeks on the notoriously wild Southern Ocean (and considerable seasickness), helicopter journeys over pristine expanses of sea ice, and long snow shoe and ski traverses. The “A” (for Antarctic) factor was a constant presence, with delays caused by heavy sea ice that trapped ships for days at a time and blizzards that grounded helicopters.</p> <p>Nevertheless, the effort paid off. Analyses of genetic data allowed us to reconstruct the population history of penguins, and correlate it with environmental conditions inferred from ice core data. The findings indicate that approximately 12,000 years ago, after the ice age ended and temperatures began to rise and sea ice around Antarctica decreased, emperor penguin numbers began to climb.</p> <p><strong>Goldilocks penguins</strong></p> <p>The emperor penguin’s relationship with sea ice can be described as a Goldilocks phenomenon.</p> <p>The penguins need stable sea ice to stand on during their breeding season. If the sea ice extent is too great then the journey between the colony and their feeding grounds in the ocean may prove too costly in terms of energy reserves.</p> <p>If there is too little sea ice or if the sea ice is not stable enough, then the penguins cannot establish successful breeding colonies. The duration of the sea ice season is also important – if the season is too short for the chicks to adequately mature, then they may not have time to grow their adult, waterproof feathers and will not survive at sea.</p> <p>During the last ice age there was about twice as much ice as there is today. Emperor penguins were probably unable to breed in more than a few locations around Antarctica. The distances from the open ocean, where the penguins feed, to the stable sea ice where they breed was probably too great in most of their modern breeding locations.</p> <p>The three populations that did manage to survive the ice age may have done so by breeding near polynyas – areas of ocean that are kept free of sea ice by wind and currents. One of the most important of these polynyas was located in the Ross Sea.</p> <p><strong>Uncertain future</strong></p> <p>Because of this Goldilocks relationship emperor penguins are facing an uncertain future. Antarctic sea ice extent has been measured using satellites for the past 35 years. In this time, large changes with very different trends in different regions have been observed.</p> <p>For the past three years in a row winter sea ice has <a href="https://theconversation.com/new-antarctic-sea-ice-record-but-scientists-arent-confounded-31676">broken records</a> for total maximum extent. This overall increasing trend masks major regional changes in the extent of the sea ice field and the duration of the sea ice season.</p> <p><a href="https://images.theconversation.com/files/72977/original/image-20150224-25670-c2ed8d.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/72977/original/image-20150224-25670-c2ed8d.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=237&amp;fit=clip" alt="" /></a> <span class="caption">Emperor penguin colonies are found right around the Antarctic continent.</span> <span class="attribution"><span class="source">Jane Younger</span>, <span class="license">Author provided</span></span></p> <p>In some areas, such as the Bellingshausen Sea, there has been a large decline in sea ice while in others, including the Ross Sea, sea ice is increasing. These fluctuations in sea ice are likely placing a huge <a href="https://theconversation.com/new-behaviour-leaves-antarctic-penguins-on-the-shelf-21849">strain on emperor penguin populations</a>, which is set to continue into the future. As areas suitable for emperor penguin breeding become scarcer it is becoming increasingly important to conserve areas known to support penguin populations.</p> <p>It’s clear that the Ross Sea was a critical area for emperor penguins in the past and this suggests it will provide an important refuge for breeding colonies in the future. This emphasises the need for careful protection of this vital part of the Antarctic ecosystem.</p> <p>A marine protected area, to protect roughly 1.34 million square kilometres of the Ross Sea from commercial fishing, was proposed by New Zealand and the United States at the last meeting of the <a href="https://www.ccamlr.org/">Commission for the Conservation of Antarctic Marine Living Resources</a> in October 2014. The proposal was rejected, but a Ross Sea marine park is likely to be on the agenda again at the 2015 meeting.</p> <p>Emperor penguins are remarkably hardy birds, surviving in one of the harshest environments on earth. However their reliance on a narrow range of suitable habitat highlights their fragility, and raises concern over their future in a world undergoing its most rapid environmental change in history.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important; text-shadow: none !important;" src="https://counter.theconversation.com/content/37800/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: http://theconversation.com/republishing-guidelines --></p> <p><span><a href="https://theconversation.com/profiles/jane-younger-155783"><em>Jane Younger</em></a><em>, PhD Candidate, Institute for Marine and Antarctic Studies, <a href="http://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a> and <a href="https://theconversation.com/profiles/karen-miller-156382">Karen Miller</a>, Adjunct Senior Lecturer, <a href="http://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a></em></span></p> <p><em>This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/genetics-reveal-antarctica-was-once-too-cold-for-penguins-37800">original article</a>.</em></p>

Family & Pets

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China's failed gene edited baby experiment proves we're not ready for human embryo modification

<p>More than a year ago, the world was shocked by Chinese biophysicist He Jiankui’s attempt to use CRISPR technology to modify human embryos and make them resistant to HIV, which led to the birth of twins Lulu and Nana.</p> <p>Now, crucial details have been revealed in a recent <a href="https://www.technologyreview.com/s/614764/chinas-crispr-babies-read-exclusive-excerpts-he-jiankui-paper/">release of excerpts</a> from the study, which have triggered a series of concerns about how Lulu and Nana’s genome was modified.</p> <p><strong>How CRISPR works</strong></p> <p>CRISPR is a technique that allows scientists to make precise edits to any DNA by altering its sequence.</p> <p>When using CRISPR, you may be trying to “knock out” a gene by rendering it inactive, or trying to achieve specific modifications, such as introducing or removing a desired piece of DNA.</p> <p>Gene editing with the CRISPR system relies on an association of two molecules. One is a protein, called Cas9, that is responsible for “cutting” the DNA. The other molecule is a short RNA (ribonucleic acid) molecule which works as a “guide” that brings Cas9 to the position where it is supposed to cut.</p> <p>The system also needs help from the cells being edited. DNA damage is frequent, so cells regularly have to repair the DNA lesions. The associated repair mechanisms are what introduce the deletions, insertions or modifications when performing gene editing.</p> <p><strong>How the genomes of Lulu and Nana were modified</strong></p> <p>He Jiankui and his colleagues were targeting a gene called CCR5, which is necessary for the HIV virus to enter into white blood cells (<a href="https://www.medicalnewstoday.com/articles/320987.php">lymphocytes</a>) and infect our body.</p> <p>One variant of CCR5, called CCR5 Δ32, is missing a particular string of 32 “letters” of DNA code. This variant naturally occurs in the human population, and results in a high level of resistance to the most common type of HIV virus.</p> <p>The team wanted to recreate this mutation using CRISPR on human embryos, in a bid to render them resistant to HIV infection. But this did not go as planned, and there are several ways they may have failed.</p> <p>First, despite claiming in the abstract of their unpublished article that they reproduced the human CCR5 mutation, in reality the team tried to modify CCR5 <em>close</em> to the Δ32 mutation.</p> <p>As a result, they generated different mutations, of which the effects are unknown. It may or may not confer HIV resistance, and may or may not have other consequences.</p> <p>Worryingly, they did not test any of this, and went ahead with implanting the embryos. This is unjustifiable.</p> <p><strong>The mosaic effect</strong></p> <p>A second source of errors could have been that the editing was not perfectly efficient. This means that not all cells in the embryos were necessarily edited.</p> <p>When an organism has a mixture of edited and unedited cells, it is called a “mosaic”. While the available data are still limited, it seems that both Lulu and Nana are mosaic.</p> <p>This makes it even less likely that the gene-edited babies would be resistant to HIV infection. The risk of mosaicism should have been another reason not to implant the embryos.</p> <p>Moreover, editing can have unintended impacts elsewhere in the genome.</p> <p>When designing a CRISPR experiment, you choose the “guide” RNA so that its sequence is unique to the gene you are targeting. However, “off-target” cuts can still happen elsewhere in the genome, at places that have a similar sequence.</p> <p>He Jiankui and his team tested cells from the edited embryos, and reported only one off-target modification. However, that testing required sampling the cells, which were therefore no longer part of the embryos - which continued developing.</p> <p>Thus, the remaining cells in the embryos had not been tested, and may have had different off-target modifications.</p> <p>This is not the team’s fault, as there will always be limitations in detecting off-target and mosaicism, and we can only get a partial picture.</p> <p>However, that partial picture should have made them pause.</p> <p><strong>A bad idea to begin</strong></p> <p>Above, we have described several risks associated with the modifications made on the embryos, which could be passed on to future generations.</p> <p>Embryo editing is only ethically justifiable in cases where the benefits clearly outweigh the risks.</p> <p>Technical issues aside, the researchers did not even address an unmet medical need.</p> <p>While the twins’ father was HIV-positive, there is already a well-established way to prevent an HIV-positive father from infecting embryos. This “<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4779710/">sperm washing</a>” method was actually used by the team.</p> <p>The only benefit of the attempted gene modification, if proven, would have been a reduced risk of HIV infection for the twins later in life.</p> <p>But there are safer existing ways to control the risk of infection, such as condoms and mandatory testing of blood donations.</p> <p><strong>Implications for gene editing as a field</strong></p> <p>Gene editing has endless applications. It can be used to <a href="https://www.nature.com/articles/d41586-019-02770-7">make plants such as the Cavendish banana more resistant to devastating diseases</a>. It can play an important role in the adaptation to climate change.</p> <p>In health, we are already seeing <a href="https://www.npr.org/sections/health-shots/2019/11/19/780510277/gene-edited-supercells-make-progress-in-fight-against-sickle-cell-disease">promising results</a> with the editing of somatic cells (that is, non-heritable modifications of the patient’s own cells) in beta thalassemia and sickle cell disease.</p> <p>However, we are just not ready for human embryo editing. Our techniques are not mature enough, and no case has been made for a widespread need that other techniques, such as preimplantation genetic testing, could not address.</p> <p>There is also much work still needed on governance. There have been individual calls for a moratorium on embryo editing, and expert panels from the <a href="https://www.nature.com/articles/d41586-019-00942-z">World Health Organisation</a> to <a href="https://en.unesco.org/news/unesco-panel-experts-calls-ban-editing-human-dna-avoid-unethical-tampering-hereditary-traits">UNESCO</a>.</p> <p>Yet, no consensus has emerged.</p> <p>It is important these discussions move <a href="https://www.nature.com/articles/d41586-019-03525-0">in unison</a> to a second phase, where other stakeholders, such as patient groups, are more broadly consulted (and informed). Engagement with the public is also crucial.</p> <p><em>Correction: this article originally described RNA (ribonucleic acid) as a protein, rather than a molecule.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important; text-shadow: none !important;" src="https://counter.theconversation.com/content/128454/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: http://theconversation.com/republishing-guidelines --></em></p> <p><em><a href="https://theconversation.com/profiles/dimitri-perrin-392467">Dimitri Perrin</a>, Senior Lecturer, <a href="http://theconversation.com/institutions/queensland-university-of-technology-847">Queensland University of Technology</a> and <a href="https://theconversation.com/profiles/gaetan-burgio-202386">Gaetan Burgio</a>, Geneticist and Group Leader, The John Curtin School of Medical Research, <a href="http://theconversation.com/institutions/australian-national-university-877">Australian National University</a></em></p> <p><em>This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/chinas-failed-gene-edited-baby-experiment-proves-were-not-ready-for-human-embryo-modification-128454">original article</a>.</em></p>

Technology

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Why some animals have different coloured eyes

<p> </p> <p><strong>Some dogs have two different coloured eyes. Do other animals (besides people) and, if so, why? – George, aged ten, Hethersett, UK.</strong></p> <p>Some dogs are born with one brown eye and one blue eye, which can look very strange, since we’re used to seeing dogs with two brown eyes. This is sometimes called “<a href="https://books.google.co.uk/books?id=pjJKkwJbLBQC&amp;pg=PA211&amp;lpg=PA211&amp;dq=heterochromia+wall+eye&amp;source=bl&amp;ots=QERmm7E3NI&amp;sig=ACfU3U3XvEL1ro-jPAjO3iVmnkAFHukTNg&amp;hl=en&amp;sa=X&amp;ved=2ahUKEwiZntXElZbjAhU8UBUIHVrwBXUQ6AEwF3oECAkQAQ#v=onepage&amp;q=heterochromia%20wall%20eye&amp;f=false">wall eye</a>”, and it’s caused by certain genes that are passed down from parents to offspring.</p> <p>If you look closely, you’ll also see that dogs with two different coloured eyes have unusually coloured coats, too. Their coats might be dappled or streaked with white. This is because the genes for eye colour and coat colour are <a href="https://www.ias.ac.in/article/fulltext/jgen/052/02/0425-0440">closely connected</a>.</p> <p>The parents themselves may not show any sign of these unusual coat or eye colours. But usually there’s at least one dog on both sides of the family tree that has the unusual colouring. That’s how the mother and father can both pass on the genes that give some of their puppies the unusual colouring.</p> <p>By now, you might be wondering – what are <a href="https://kids.britannica.com/kids/article/gene/603646">genes</a>? Let me explain: every living thing is made up of cells. Each cell contains all the information needed to tell the body what to look like and how to work. Every little bit of information is called a “gene”, and there are lots and lots of genes which decide nearly every aspect of how we are.</p> <p><strong>Passed down from parents</strong></p> <p>For example, there are <a href="https://www.sciencedaily.com/terms/human_genome.htm">around 25,000 genes</a> in human cells, which can decide everything from our height, to our hair colour or how likely we are to get certain diseases. The genes are made up of DNA, and held together on stringy structures called “chromosomes” in the centre of the cell.</p> <p><a href="https://images.theconversation.com/files/282211/original/file-20190702-126364-gkw5od.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/282211/original/file-20190702-126364-gkw5od.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="" /></a> <span class="caption">See inside a cell, where genes are made of DNA.</span> <span class="attribution"><a href="https://en.wikipedia.org/wiki/Chromosome#/media/File:Eukaryote_DNA-en.svg" class="source">Wikimedia Commons/Magnus Manske.</a>, <a href="http://creativecommons.org/licenses/by-sa/4.0/" class="license">CC BY-SA</a></span></p> <p>Because every mammal comes from two parents, it has two copies of every gene – one from the mother and one from the father. Each copy may be telling the body to do something different. For example, the mother’s gene might be saying “dark hair” while the father’s says “fair hair”.</p> <p>In that case, the mother’s gene will win and their baby will have dark hair, because the dark hair gene is dominant over the fair hair gene. The baby will only have fair hair if both parents pass on the gene for fair hair.</p> <p>The genes for wall eye and streaky coat are similar to the fair haired gene, in this way. An animal will only have those features if that specific gene is passed down from both parents. When the mother and father carry the gene, but don’t have wall eye themselves, then some of their offspring will have it, though not all of them.</p> <p><strong>Wall eye woes</strong></p> <p>Wall eye is also sometimes seen in rabbits, cats, cattle, sheep and horses. Horses that have one blue eye usually have black and white patches on their coat – they are called “piebald” or “pinto” or “paint”. Some of these horses even have two blue eyes (one of mine does!), which makes them look even more unusual.</p> <p>Humans can also have one blue eye and another of a different colour, like brown or green. This often goes with a white streak in the front of their hair.</p> <p>Sometimes, having wall eye can cause problems. For dogs, the eye that is blue often has problems that <a href="https://www.ias.ac.in/article/fulltext/jgen/052/02/0425-0440">can affect its sight</a>. For this reason, breeders don’t let two dogs with wall eye and streaky coat have puppies together. If they do, then the puppies will often be blind and sometimes deaf as well.</p> <p>In horses, wall eye does not seem to cause problems with vision, though having two blue eyes can be <a href="https://journals.plos.org/plosgenetics/article/file?id=10.1371/journal.pgen.1002653&amp;type=printable">associated with deafness</a>. Some cats and humans who have it can also have trouble hearing, and humans whose parents both have wall eye may be unable to speak or hear.</p> <p><em><a href="https://theconversation.com/profiles/jan-hoole-384563">Jan Hoole</a>, Lecturer in Biology, <a href="http://theconversation.com/institutions/keele-university-1012">Keele University</a></em></p> <p><em>This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/curious-kids-why-do-some-animals-have-two-different-coloured-eyes-119727">original article</a>.</em></p>

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The most common genetic kidney disorder you've probably never heard of

<p>Autosomal-dominant polycystic kidney disease (<a href="https://pkdaustralia.org/adpkd/">ADPKD</a>) is the most common genetic kidney disorder, and the <a href="https://www.anzdata.org.au/report/anzdata-41st-annual-report-2018-anzdata/">fourth most common</a> cause of kidney failure in Australian adults. It affects about <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/imj.13143">one in 1,000 Australians</a>.</p> <p>In people with ADPKD, a mutation in one or two genes leads to the development and progressive growth of cysts in the kidneys, causing a decline in kidney function.</p> <p>Labor senator Malarndirri McCarthy, a Yanyuwa woman, recently spoke publicly about having ADPKD after <a href="https://www.smh.com.au/politics/federal/senator-reveals-kidney-disease-that-saw-her-leave-question-time-for-hospital-20190802-p52d8w.html">she became unwell</a> with a kidney infection and had to leave the Senate.</p> <p>But a newly available treatment for ADPKD shows promise for people with the disease.<a href="http://theconversation.com/explainer-what-is-chronic-kidney-disease-and-why-are-one-in-three-at-risk-of-this-silent-killer-81942"></a></p> <p><strong>What is ADPKD?</strong></p> <p>If one parent has ADPKD, the children have a 50 per cent chance of inheriting the gene (though <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/imj.13143">up to 10 per cent</a> of patients don’t have a family history).</p> <p>Where it is inherited, the age of diagnosis and rate of progression to kidney failure in the parent gives some indication of how the disease will develop in affected children.</p> <p>The cysts are like balloons filled with water, which start small in childhood and increase in size over time.</p> <p>Typically, the cysts don’t start to cause problems until later in life. The average age at diagnosis is <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa1402685">27 years</a>.</p> <p>As the cysts grow, normal working tissue in the kidney is replaced with enlarging cysts. So with time, the kidneys don’t work as well.</p> <p>For about <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/imj.13143">half of people with ADPKD</a>, their condition will eventually progress to kidney failure, which may be treated with dialysis or a transplant.</p> <p>While the loss of kidney function is paramount, the cysts may cause other symptoms and complications too.</p> <p>Symptoms can include high blood pressure and chronic pain or heaviness in the back, sides and abdomen. The growth of cysts means the kidneys can grow to as large as <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1464-410X.2007.07229.x">5-6kg in size</a>.</p> <p>Blood in the urine, urinary tract infections, kidney stones and infections in the cysts are not uncommon in people with ADKPD, and can all impact quality of life.</p> <p>Other organs may also be affected. People with ADPKD can develop cysts in the liver, pancreas and bowel, and about 10 per cent will experience balloon dilations of the <a href="https://www.ncbi.nlm.nih.gov/pubmed/26260542">blood vessels in the brain</a>, called aneurysms.</p> <p><strong>Treatment</strong></p> <p>Until recently, treatment of ADPKD was directed towards early detection, control of blood pressure, lifestyle measures such as quitting smoking, weight control and diet, antibiotics for infections, analgesics for pain and the management of progressive kidney dysfunction via dialysis and transplantation. None of these therapies however directly slowed the growth of cysts.</p> <p>But on January 1, 2019, tolvaptan <a href="https://pkdaustralia.org/news/">was listed</a> on the Pharmaceutical Benefits Scheme. Australia now joins the United States, the European Union, and several other countries where this drug was already available.</p> <p>Tolvaptan, which is taken in tablet form, slows the growth of cysts by <a href="https://www.ncbi.nlm.nih.gov/pubmed/28379536">blocking a hormone called vasopressin</a>. Vasopressin is critical in triggering the formation of cysts. In this way, tolvaptan prolongs the time to kidney failure.</p> <p>In one study, three years of treatment with tolvaptan <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa1205511">reduced the rate of cyst growth</a> by around 50 per cent in comparison to a placebo treatment. The authors suggested tolvaptan may delay dialysis or the need for a transplant for six to nine years for patients with ADPKD, particularly if started early.</p> <p>People who took tolvaptan in this study also had lower incidence of ADPKD-related complications including urinary tract infections and kidney pain.</p> <p><strong>Kidney disease and Indigenous Australians</strong></p> <p>ADPKD is not actually more common in Aboriginal and Torres Strait Islander communities, as other causes of <a href="https://www.menzies.edu.au/page/Research/Indigenous_Health/Diabetes_and_kidney_disease/Kidney/">chronic kidney disease</a> are. This may be because ADPKD is inherited.</p> <p>The majority of chronic kidney disease develops as a complication of diabetes, which affects Aboriginal and Torres Strait Islander populations more commonly and typically <a href="https://www.menzies.edu.au/page/Research/Indigenous_Health/Diabetes_and_kidney_disease/Diabetes/">at a younger age</a> than the overall Australian population.</p> <p>Kidney disease, whatever the cause, remains a significant issue for Aboriginal and Torres Strait Islander communities. People in remote Indigenous communities in particular face challenges around accessing treatments in large urban centres, and have poorer access to organ transplants.</p> <p>There are several nationally targeted activities and proposals aimed at reducing the burden of chronic kidney disease in Indigenous Australians.</p> <p>The <a href="https://www.menzies.edu.au/icms_docs/281923_Roundtable_Towards_Roadmap_For_Renal_Health_-_Media_Release.pdf">Renal Health RoadMap</a> is designed to support health systems in early detection and management of diabetes and chronic kidney disease. It also seeks to address the social determinants of poor health in Indigenous communities, including housing quality and availability, and health infrastructure.</p> <p>In 2018, Minister for Indigenous Australians Ken Wyatt commissioned <a href="https://www.tsanz.com.au/TSANZ%20Performance%20Report%20-%20Improving%20Indigenous%20Transplant%20Outcomes%20(Final%20edited)-1.pdf">a report</a> detailing how access to and outcomes of kidney transplants could be improved among Indigenous Australians. He also established a <a href="https://www.anzdata.org.au/anzdata/for-information-2/tsanz/">National Indigenous Kidney Transplantation Taskforce</a> to implement the recommendations from this report.</p> <p>Some key recommendations include improving the communication between health-care teams, patients and their families, addressing cultural bias in the delivery of health care, and improving the quality of data around transplant access and outcomes.</p> <p>Addressing transplant and treatment inequities will benefit Indigenous Australians with kidney failure sustained from ADPKD and chronic kidney disease more broadly.</p> <p><em>Written by <span>Karen Dwyer, Deputy Head, School of Medicine, Deakin University and Jaquelyne Hughes, Senior Research Fellow, Menzies School of Health Research</span>. Republished with permission of </em><a rel="noopener" href="https://theconversation.com/polycystic-kidney-disease-the-most-common-genetic-kidney-disorder-youve-probably-never-heard-of-121441" target="_blank"><em>The Conversation</em></a><em>. </em></p>

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