Behind the Genes

By: Genomics England
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  • Summary

  • We are Genomics England and our vision is to create a world where everyone benefits from genomic healthcare. Introducing our refreshed podcast identity: Behind the Genes, previously known as The G Word. Join us every fortnight, where we cover everything from the latest in cutting-edge research to real-life stories from those affected by rare conditions and cancer. With thoughtful conversations, we take you behind the science. You can also tune in to our Genomics 101 explainer series which breaks down complex terms in under 10 minutes.
    Copyright 2021 All rights reserved.
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Biological Sciences Social Sciences
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Episodes
  • Meriel McEntagart: Are genetic conditions always inherited from parents?

    Meriel McEntagart: Are genetic conditions always inherited from parents?
    Nov 27 2024
    In this explainer episode, we’ve asked Meriel McEntagart, Clinical Geneticist in the NHS and Clinical Lead for Rare Disease Technologies at Genomics England, to explain how genetic conditions can be inherited, and other ways they may arise. You can also find a series of short videos explaining some of the common terms you might encounter about genomics on our YouTube channel. If you’ve got any questions, or have any other topics you’d like us to explain, feel free to contact us on info@genomicsengland.co.uk. To learn more about X-linked inheritance, as mentioned in the episode, tune in to our explainer episode, how does X-linked inheritance work? You can download the transcript or read it below. Florence: Are genetic conditions always inherited from parents? I'm joined by Meriel McEntagart, clinical geneticist for the NHS to find out more. So, Meriel, first things first. How can a genetic change cause a condition? Meriel: We have about 20,000 genes. That's the estimate and they are the code or blueprint for how to grow and develop a human being. And, if you think about a code, you can have a mistake in a code or a variant in a code. And if that happens, such as one genetic letter being changed for another, the result can be that the code doesn't give the correct instructions about how to grow and develop that human being. There are lots of different ways in which those changes can happen. Florence: And how can we inherit conditions from our parents? Meriel: Well, for the most part, like I mentioned, we've got 20,000 pairs of genes and we get one of each pair from our mother and our father. And so, for lots of genetic conditions, they follow a pattern of inheritance where one copy of that pair of genes has got the variant or spelling mistake in it, which causes the condition. So just having a single mistake in that pair of genes is enough to cause you to develop the symptoms of the condition. Other conditions show where you only develop the condition if both copies of the pair, the one you get from your mother and the one you get from your father have got a variant or a spelling mistake in the gene. So, you actually don't have a working copy of that gene. There are other patterns of inheritance as well. And so, we talk about X-linked inheritance. That can arise because women have what we call two X chromosomes; men only have one X chromosome. Florence: If you want to learn more about X-linked Inheritance, you can check out our previous podcast. How does X-linked inheritance work? So then do parents who have a condition always pass it on to their children? Meriel: So, this is again, where we think about some of those patterns of inheritance that I've just mentioned. If somebody has a condition, for example, a dominant condition, they will have that variant or genetic change that's causing their condition in one of their pair of genes. So then it's 50:50 when they have a child, whether they pass on the gene that's carrying that variant or not, because the child will be getting the other copy of that pair from their partner. If they do inherit that copy with the variant in it, then they will develop the symptoms of the condition in most cases. In some situations, however, a parent can have a genetic condition. So, they develop symptoms of the condition, and as I've mentioned, it's 50:50, whether it gets passed onto the child, so the child could actually inherit that genetic variant, but potentially not show signs of the condition. And this is what we call ‘reduced penetrance’. This means you can carry a genetic variant and probably some other event has to take place to cause you to develop symptoms. So that might be that there's other genetic factors that you inherit that trigger you to develop symptoms or there might be an illness or something that you experience that brings out the expression of that gene. So that's quite an important, consideration when we're looking at genetic variants and whether somebody will develop symptoms. Florence: And finally, how do we develop conditions that don't come from our parents? Meriel: Well, I suppose the main explanation for that is what we call a de novo genetic event. So that can arise when we are conceived. So for example, genes get copied to be put into the sperm or our genes get copied to be put into the egg. And in that process of making the sperm and the egg, a spelling mistake or mutation can arise in the DNA and then that sperm or that egg, whichever one has it, takes that forward into making the baby. And then the baby from that point will have that genetic variant in every single cell in their body. So it hasn’t come from the parents, so it’s not inherited but it still is a genetic condition. This is something that now that we're able to do whole genome sequencing, we are finding is a more common explanation for developmental disorders or conditions in children than we previously appreciated. And quite a lot of ...
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    6 mins
  • Helen White, Professor Ian Tomlinson, Claire Coughlan and Dr David Church: Can genetic discoveries revolutionise bowel cancer care?

    Helen White, Professor Ian Tomlinson, Claire Coughlan and Dr David Church: Can genetic discoveries revolutionise bowel cancer care?
    Nov 20 2024
    In this episode, we explore findings from a groundbreaking study recently published in Nature which revealed potential targets for bowel cancer prevention and treatment. The study provides the most detailed understanding yet of bowel cancer’s genetic makeup. The research, which used data from the 100,000 Genomes Project identified over 250 genes that play a crucial role in the condition, driver genes and potential drug targets. Our guests discuss the potential impact of these findings on patient outcomes, screening for bowel cancer, and future prevention strategies. Helen White, Participant Panel Vice-Chair for Cancer at Genomics England is joined by Professor Ian Tomlinson, Professor of Cancer Genetics at the University of Oxford, Claire Coughlan, Clinical Lead for Bowel Cancer UK and consultant nurse in colorectal cancer, and Dr David Church, a clinical scientist fellow and a medical doctor specialising in oncology at Oxford University. "The people that were kind enough to donate samples to the 100,000 Genomes Project, they did so knowing that they almost certainly wouldn’t benefit personally from their donation from their gift and that any benefits would be some way down the line and hopefully benefit others which is what we’re seeking to realise now. But, you know, it’s not a given when we treat people in the clinic so we’re very, very grateful to those individuals." You can read more about the study in our colorectal cancer blog and our study findings news story. You can download the transcript or read it below. Helen: Welcome to Behind the Genes. Ian: One of the great hopes is that some of these new genes that we’ve found could be useful in preventing cancer and it doesn’t necessarily matter that they’re rare, even if they’re only 1% of cancers, by using those and changing those in the normal individual before they have had cancer then we may be able to reduce that risk. So, there are lots of potential new targets for prevention that are coming through. My name is Helen White and I’m the Participant Panel Vice-Chair for Cancer at Genomics England. Today I’m delighted to be joined by Professor Ian Tomlinson, Professor of Cancer Genetics at the University of Oxford, Claire Coughlan, Clinical Lead for Bowel Cancer UK and consultant nurse in colorectal cancer, and Dr David Church, a clinical scientist fellow and a medical doctor specialising in oncology at Oxford University. Today we will be discussing a pioneering colorectal cancer study which using data from the 100,000 Genomes Project has uncovered new insights that could transform diagnosis and treatment for patients with bowel cancer. If you enjoyed today’s episode we would love your support, please like, share and rate us on wherever you listen to your podcast. Thank you for joining me today. We’re going to be discussing the findings from a landmark study that has been published in nature. This study used data generously donated by people with bowel cancer who took part in the 100,000 Genomes Project giving us the most detailed look yet at the genetic makeup of colorectal cancer better known as bowel cancer. But before we get into that let’s start by hearing from my guests. Could each of you please introduce yourselves. Ian: I’m Ian Tomlinson, I work at the University of Oxford and most of my work is research into bowel cancer, it’s genetic causes, the genes that are involved in actually causing the cancer to grow which may be different from genetic causes and also the use of that data to help patients whether guiding future treatments or potentially helping to prevent bowel cancer which would obviously be our optimum strategy to have the biggest impact on the disease and its incidents. Claire: So, I’m Claire Coughlan, I’m the clinical lead for Bowel Cancer UK and my remit at the charity is to ensure that everything we do is clinically relevant and that we’re providing services that meet the needs of those affected by bowel cancer and the educational needs of those health professionals that work with people affected by bowel cancer. I’m also a nurse consultant in colorectal cancer at Lewisham and Greenwich NHS Trust and I lead an urgent referral service there and also work with patients with late effects of bowel cancer. David: I’m David Church, I’m a medical oncologist and Cancer Research UK advanced clinician scientist at the University of Oxford. I treat bowel cancer clinically and do research on bowel cancer and womb cancer including a lot of research using samples and data from Genomics England data service we’re discussing today of course. Helen: Great, thank you. Now let’s turn to Claire to learn more about bowel cancer. Claire, can you share with us how common it is, how treatable it is and if there are any trends in terms of which groups of people are affected? Claire: Of course, bowel cancer is a relatively common cancer, there are about 46,000 people each year in ...
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    34 mins
  • Adrianto Wirawan: What does 'no primary findings' mean?

    Adrianto Wirawan: What does 'no primary findings' mean?
    Nov 13 2024

    In this explainer episode, we’ve asked Adrianto Wirawan, Director of Bioinformatics Engineering at Genomics England, to explain what the term 'no primary findings' means.

    You can also find a series of short videos explaining some of the common terms you might encounter about genomics on our YouTube channel.

    If you’ve got any questions, or have any other topics you’d like us to explain, feel free to contact us on info@genomicsengland.co.uk.

    You can download the transcript or read it below.

    Florence: What does ‘no primary findings’ mean? I'm joined by Adrianto Wirawan, Director of Bioinformatics Engineering for Genomics England, to find out more. So firstly, Adrianto, when we speak about findings from genomic tests, what does this mean? What are we looking for when we do a genomic test?

    Adrianto: Our DNA is made up of a long sequence of letters that act like instructions for your body.

    Genomic testing analyses these letters to see if there are any unusual patterns or changes that might change your health. You can imagine your DNA as a book full of recipes for your body. Every recipe tells your body how to make proteins that keep you healthy, and sometimes there might be a typo in the recipe, like missing an ingredient or mixing up the steps. This could result in a health problem, just like how a changed recipe can lead to a bad dish.

    On average, we would expect about 5 million out of our 3 billion DNA letters to be different. And each of these, we call them a genetic variant. Genomic testing is designed to examine some of these variants to help inform our healthcare. So, for example, in understanding why certain health problems happen and in choosing the best treatment based on our unique genetic makeup.

    Florence: And what do we mean by primary findings?

    Adrianto: Primary findings mean that in a patient's genomic testing, we identified a set of variants that is linked to the patient's condition. The variants that we have makes us who we are. However, not all of them cause a disease or contribute to a health problem. our bioinformatics pipelines will automatically prioritise variants of potential relevance to the patient's conditions. Using this data, the NHS clinical scientists will then determine whether any of these prioritised variants are linked to the patient's condition and whether a genetic diagnosis has been identified, which would explain why certain health problems happen.

    Florence: So, then what happens when there are no primary findings?

    Adrianto: When no primary findings are found, that means that no genetic diagnosis has been identified. As developments are made and our knowledge of the variance improves over time, additional findings might be identified in the future.

    The clinical team responsible for a patient's care may request reanalysis of data according to the national guidance, following a change in the patient's clinical status to inform reproductive decisions, or after significant new disease gene associations have emerged.

    In addition, Genomics England also provides the diagnostic discovery pathway where we focus on uncovering new diagnosis, where the participants of the 100,000 Genomes Project, as well as the patient's sequenced through the NHS Genomic Medicine Service

    This is meant to be more equitable as we don't rely on the clinical teams to raise individual separate requests.

    Florence: And finally, what do we mean by secondary findings?

    Adrianto: Secondary findings are additional findings not related to the conditions in which the patient was recruited for. For example, if a patient was recruited for one type of cancer, but perhaps we found variants linked to a different condition. We explored secondary findings for the 100,000 Genomes Project but we do not do secondary findings for the Genomic Medicine Service.

    Florence: That was Adrianto Wirawan explaining what we mean by ‘no primary findings’. If you'd like to hear more explainer episodes like this, you can find them on our website at www.genomicsengland.co.uk.

    Thank you for listening.

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    4 mins

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