Date(s) - 23/04/2015
2:00 pm - 3:00 pm
SGDP Seminar Room
Professor of Statistical Genetics, London School of Hygiene and Tropical Medicine
Explaining heritability and predicting risk with polygenic scores
Much of the genetic basis of complex traits is present on current genotyping products, but the individual variants that affect the traits have largely not been identified. Polygenic scores, formed by summing risk alleles over thousands of markers, offer a simple yet effective way to access the heritability as a whole. I review applications of polygenic scores to establish a polygenic effect, demonstrate a shared genetic basis for related traits, predict individual disease risks, and infer causal effects using Mendelian randomization. I give a theoretical analysis of the method and show that studies of hundreds of thousands of subjects are needed to achieve clinically useful genetic risk prediction. I describe new methods using polygenic scores to estimate the heritability explained by genotyping chips, the proportion of variants with effects on a trait, and the genetic covariance between related traits.