The Genetics of Skin Pigmentation

How many genes determine human skin color? This question is deceptively simple and direct. Although there are over 100 genes that can lead to clinically-significant pigmentary disorders such as albinism, only four genes are responsible for most of the skin color differences between West African and European populations. The genes that underlie skin color differences between populations are usually also genes that can cause pigmentary disorders. Genes that affect skin color variation in humans also generally affect pigmentary variation in other species. Thus, evolutionary approaches to understanding which genes affect pigmentation can provide important insights into both normal development and pathophysiology. Likewise, genetic and genomic investigations can help illuminate where and when the genes that affect contemporary skin color levels changed and, ultimately, which evolutionary forces shaped the wide range of skin colors we see today.