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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Episodes
  • Callum Morris: What happens in a clinical trial?

    Callum Morris: What happens in a clinical trial?
    Oct 30 2024
    In this explainer episode, we’ve asked Callum Morris, Pharmaceutical Research and Development Insights Manager at Genomics England, to explain what happens in a clinical trial. 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 read the transcript below or download it here: https://www.genomicsengland.co.uk/assets/documents/Podcast-transcripts/What-happens-in-a-clinical-trial.docx Florence: What happens in a clinical trial? I'm joined with Callum Morris, Pharmaceutical Research and Development Insights Manager for Genomics England, to find out more. So, Callum, first things first. What is a clinical trial? Callum: So, a clinical trial is a study that looks to people to answer a specific medical research question. So, this involves gathering a group of participants that are willing to participate in providing evidence on how to improve clinical care. And so, the main purpose for a clinical trial is to evaluate health related outcomes between different groups of participants. If it's an interventional clinical trial, you change clinical care for one group and not another. And evaluate whether the change you made improved health outcomes for that group, or if it's an observational clinical trial, you might focus on different groups but not change anything about their clinical care and collect real world data to understand how outcomes differ across the groups. Florence: Can you briefly explain what we mean by real world data? Callum: Sure. So real world data relates to data collected routinely as part of standard clinical care. So, it could be collected from your electronic health records, data from product or disease registries, or data gathered from other sources such as digital health technologies. And all of this can inform on particular groups from the population you're interested in. Florence: And are there different types of clinical trials? Callum: Yes. Clinical trials can take many forms depending on the medical research question you're trying to answer. They could be related to understanding the risk of disease. So, evaluating a potential risk factor that you may be concerned with. They might evaluate preventing disease. So, what different approaches can you take to people who have never had the disease, and does this prevent its occurrence? You can have a clinical trial that looks at screening for disease. For cancer, that's really important. Does a new screening approach mean more people with cancer can be identified earlier? And importantly, does this lead to an improvement in survival? You can have clinical trials that evaluate the different approaches to diagnosing a disease and can you diagnose a patient earlier and better? And then the classical clinical trial is revolving therapeutics or different treatments, and you can have treatments that are addressing the disease itself. Or you'd have treatments that are controlling the symptoms of side effects you might get from another treatment you might be taking. So even within a specific medical research question, you can have different clinical trials depending on how much evidence you already have regarding that question. For clinical trials involving the assessment of new treatments and therapies, these are broken down into three stages and we call these phases. So, you have phase one, phase 2, and phase 3. Florence: Can you explain a bit more about these phases? Callum: Sure. So, the overarching medical research question might be, what is the safety profile of this new therapy, and does it work improving on the current standard of care? So, you'll break this down depending on the phase, and with each phase you expand your clinical trial to a larger population. Phase ones are typically on a small group of people around, let's say 20 to 50, and are designed to check the safety of a new drug that's being entered into humans for the first time. Sometimes, especially in early phase cancer trials, you're trying to find the right dose for your patients. So, you might take a small group, test them on a low dose, and if there are no severe reactions to the new drug, you start incrementally increasing your dose a little bit more. And this gives you a really good idea of the safety profile of your drug as you try it for the first time in a human population. Next, you'll move on to a phase 2. And these are typically larger than your phase one, around 50 to 200 people. And, usually you use the dose recommended by the phase one. So instead of slowly adjusting your dose and just focusing on the drug safety profile, the phase 2 will evaluate the safety of the medicine in a large population, but also have an additional focus on health-related outcomes. Is the medicine ...
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    8 mins
  • Nicole Chai: How does X-linked inheritance work?

    Nicole Chai: How does X-linked inheritance work?
    Oct 23 2024

    In this explainer episode, we’ve asked Nicole Chai, Research and Development Bioinformatician at Genomics England, to explain what X-linked inheritance is.

    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 read the transcript below or download it here: https://www.genomicsengland.co.uk/assets/documents/Podcast-transcripts/How-does-X-linked-inheritance-work.docx

    Florence: How does X-linked inheritance work? I'm joined by Nicole Chai, Research and Development Bioinformatician for Genomics England, to find out more. So firstly, Nicole, can you explain a bit about the X and Y chromosomes?

    Nicole: Sure. So, the X and Y chromosomes are what we call sex chromosomes. And chromosomes are packages of DNA in our cells that are inherited from our parents, and they contain information about our physical and biological traits.

    Some examples of traits that are determined by our chromosomes include what colour our hair is and what colour our eyes are. And each of these individual traits are determined by smaller sections on the chromosome called genes. Genes can also determine what medical conditions we may inherit from our parents.

    As humans, we all typically have 23 pairs of chromosomes in each of our cells. One of these pairs consists of the sex chromosomes, and as their name suggests, sex chromosomes determine sex of an individual. And typically, females will have two X chromosomes and males will have one X and one Y chromosome.

    Florence: So then, what do we mean by the term X-linked condition?

    Nicole: So, an X-linked condition means that the condition is associated with genetic changes on the X chromosome. And what we mean when we say genetic changes are changes to the normal sequence of DNA on the gene. And this can sometimes lead to medical disorders.

    Florence: Do you have a specific example of an X-linked condition?

    Nicole: Sure. So, an example of an X-linked condition is Duchenne muscular dystrophy.

    And with this condition you get a progressive loss of muscle due to the lack of a protein known as dystrophin. Another example of an X-linked condition is red-green colour blindness. And this is where people affected with the condition can't see shades of red and green the way most people see them.

    Florence: Could you explain how X-linked conditions are inherited?

    Nicole: Sure. So, for many conditions, there are two ways they can be inherited, either dominantly or recessively. Dominant inheritance is usually when you just need one copy of the gene to be affected by the condition, whereas recessive inheritance is when you need two copies of the gene to be affected by the condition.

    However, this works slightly differently with X-linked conditions, and most X-linked conditions are inherited recessively.

    Florence: So why does inheritance work differently for X-linked conditions?

    Nicole: So the reason that inheritance works differently for X-linked conditions is down to the differences between sex chromosomes, between females and males. As females have two X chromosomes and males have X and Y, this means that for recessive excellent conditions, males only need one altered gene to have the condition.

    So, because males only have one X chromosome, if they inherit a faulty copy of a recessive gene, they don't have another healthy copy to compensate.

    On the other hand, as females have two X chromosomes, if they inherit just one faulty copy, they do have a healthy one that can compensate for that one. So as a result, what we tend to see is that males are more commonly affected by X-linked recessive conditions.

    Florence: That was Nicole Chai explaining the term X-linked inheritance. If you'd like to hear more explainer episodes like this, you can find them on our website www.genomicsengland.co.uk. Thank you for listening.

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    3 mins
  • Arina Puzriakova: What is a polygenic disorder?

    Arina Puzriakova: What is a polygenic disorder?
    Oct 16 2024
    In this explainer episode, we’ve asked Arina Puzriakova, Scientific Curator at Genomics England, to explain what a polygenic disorder is. 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 read the transcript below or download it here: https://www.genomicsengland.co.uk/assets/documents/Podcast-transcripts/What-is-a-polygenic-disorder.docx Florence: What is a polygenic disorder? I'm joined by Arina Puzriakova, Scientific Curator for Genomics England to find out more. So, Arina, first things first. How can our genes affect our health? Arina: So, genes are short sections of DNA that contain information that the cells in your body need in order to make proteins. Each gene carries the instructions for making a specific protein, and each protein performs a different task that allows the body to develop and function properly, depending on the genes that we inherit from our parents. Also determines our unique physical features such as our eye colour, hair colour, and height. When a gene contains a change that disrupts the gene's instructions, also known as a gene variant, in some cases, this can lead to the production of a defective protein or prevents a protein from being made altogether. A missing protein or one that is not working properly can have a knock-on effect on how the body functions and this can result in health issues or the development of a genetic disorder. Florence: So then how can a gene variant lead to a disorder? Arina: So the genetics of each disorder are unique. In some cases, a change in a single gene is enough to cause a genetic disorder, and these are known as monogenic disorders. These conditions often occur in childhood and tend to cause severe illness. individually, they are more rare affecting a smaller number of people in the population, and usually they run in families as parents pass the damaging variance onto their children. But these changes can also happen spontaneously without a known cause. An example of a monogenic disorder, which some may be familiar with, is cystic fibrosis. Cystic fibrosis affects one in every 2,500 babies born in the UK, meaning that there's about 11,000 people living with cystic fibrosis. Florence: So, we've just talked through monogenic disorders. What do we mean by polygenic disorder? Arina: So polygenic disorders are on the other end of the spectrum for disorders. They are caused by the combined effects of multiple different genes. Individually, each gene has a very small effect on causing the disease, but many variations in different genes can act together to have a great impact on individual's susceptibility to that condition. Environmental and behavioural factors such as your lifestyle and diet also often have an effect. Polygenic disorders are much more common, typically affecting millions of people in the population, and they're usually diagnosed in adulthood. Florence: Could you give me an example of a polygenic disorder? Arina: A common example of a polygenic disorder is type two diabetes. It affects almost 4 million people in the UK. So this means that we know there are many genetic variants that could have made these individuals more susceptible to diabetes, but there are also other factors such as age or being overweight that could have increased their risk. Florence: Are there specific challenges when it comes to diagnosing or treating polygenic disorders? Arina: So, if I start with monogenic disorders, these are much easier to test for because we simply need to look for the presence or the absence of a faulty gene in order to determine whether someone is a carrier of a genetic disorder. On the other hand, testing for a polygenic disorder is a lot more complex as they are influenced by the combined effects of many genes. Meaning there is no single genetic test or treatment that will work for all patients with the same condition. We need large and diverse groups of patients to study in order to accurately determine which genes are important and which ones are not. And this can be challenging to obtain. Also accurately measuring and comparing lifetime environmental factors and exposures further complicates the assessment. Another challenge with polygenic disorders is that even though they can cluster in families, the inheritance is not as clear cut or predictable as it is with monogenic disorders. Carrying a specific combination of genetic variants that are already known to be associated with polygenic disorder does not necessarily mean that you will definitely develop that disorder. However, this information can be used to calculate something known as a polygenic risk score, and this provides an estimate for the risk of developing polygenic disease at some ...
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    6 mins

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