Other Talks in the Series: Statistical Genetics

My name is Doug Speed, and I'm a Researcher at University College London Genetics Institute. And today, I will be telling about Heritability and Its Uses. And hopefully, I'll convince you why this is the most exciting area in Quantitative Genetics.
So there are two parts in this talk. First, I'll tell you about traditional heritability analysis, and then, I'll talk to you a bit about SNP-based heritability analysis, which is a very recent area in the last five years, and hopefully, I will give you an idea of all the uses it has in trying to understand complex trades. So first of all, here are few books and papers
which I find very useful. The first one is Introduction to Quantitative Genetics, and this has more details on lots of the first part of this talk. I've a second too, Introductory Statistics with R and Elements of Statistical Learning are both available at the author's web pages to view online. And then here I have major papers in the field of SNP-based heritability analysis, and so it'll be useful for later.
It's a bit hard to tell in that previous slide, so I've just added a bit of noise so you can see the individual SNP genotypes.
So here we see that adding in copies of the mutant allele increases phenotype on average. So for example, if an individual has one copy, so it's genotype AG, for example, then their effect is higher than if they have zero copies AA. And then, if they have two copies GG, their effect is the same amount higher still. And what we can observe is a linear trend, so each copy of the mutant allele increases for phenotypic effect by the same quantity. So heritability is a fundamental concept in quantitative genetics. Really, if you plan to do a genetic analysis of a phenotype, one of the first things you should think about is, what is the heritability of a trait you wish to study. If the heritability is zero, then there's no point doing a genetic analysis, because there are no genetic factors influencing the trait. Whereas, if the heritability is very high,