How can genomics help us understand rare conditions?

In this explainer episode, we’ve asked Jamie Ellingford, Lead Genomic Data Scientist for Rare Disease, to explain how genomics is helping us better understand rare conditions.

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, let us know on [email protected].

You can download the transcript or read it below.

[00:00:00] Florence: How can genomics help us better understand rare conditions? My name is Florence Cornish, and today I am joined by our Lead Genomic Data Scientist for Rare Disease, Jamie Ellingford, and he is going to be sharing lots more insights about the topic with us.

So, I guess before we begin, Jamie, it might be useful if you could explain what we actually mean by the term 'rare condition'? 

[00:00:25] Jamie: Sure. Hi, Florence. So, a rare condition we define as something that impacts one in less than two thousand people, and so that's something that occurs really infrequently in the population. But we know that collectively there's lots of different rare diseases. And so, the estimates are that it's about one in seventeen people in the population that are impacted by some sort of rare disease, of which we think there's over seven thousand.

But research that uses data that we have here at Genomics England as well as other sources is starting to uncover more and more of these individual rare disorders. So collectively, as I just said, one in seventeen individuals, we think, is impacted by a rare disease, and that equates to almost three and a half million people here in the UK. 

[00:01:15] Most of these rare conditions, we think, have a genetic basis, and perhaps we'll explain a little bit more about what that means.

[00:01:22] Florence: Yeah, no, it would be great to talk a little bit more about that actually. So as you said, most rare conditions we think have a genetic cause, but I think it might be helpful if you could explain what we mean when we say that something 'has a genetic cause'. 

[00:01:35] Jamie: Of course. So maybe we go back to kind of the basics and kind of how a person is first formed. So, at that point of fertilisation, where the sex cells from mum and dad join, we inherit one copy of our genome from mum and one copy from dad, and it's the order and the composition of these letters in our genome which makes it unique to us. 

Most of that genome is absolutely identical to anyone else in the human population. And a small fraction of it is unique to us and is a combination of things that we've inherited from our mothers and our fathers. And when we think about genetic causes, largely, we look at those differences. And so, what is it that's different in individuals compared to the wider population that could be driving these rare conditions? 

[00:02:23] Florence: So could you maybe explain a little bit more about how people's genetic material, how people's genomes differ from one another? 

[00:02:30] Jamie: So there's lots of different ways that we can observe these genetic differences. So some of them impact individual letters, and we, we may swap a single letter for another.

[00:02:41] We can also remove small sections, so it may be that a run of three or four of these letters is deleted from someone's genome. But on the opposite end of the scale, we can also see huge changes in how that genetic material looks.

So perhaps a good way to think about this is as a story. And so if our, if our genome is like any kind of good fiction story that you would read, then we can have spelling mistakes that impact single words,