One thing I didn’t mention in the notes for Thursday’s lecture is that it is difficult to detect the effect of loci where one variant is rare, both because there’s a good chance you won’t have the variant in your sample (unless your sample is very large) and because it’s difficult to detect an effect when only a small number of individuals show it. The most recent Nature has a news article highlighting the challenge using our favorite polygenic trait, height in humans.
Genetic study homes in on height’s heritability mystery