This article reports on a meta-analysis of two genome-wide association studies (GWASs) of skin pigmentation using skin reflectance (M-index) as a quantitative phenotype, with one study being a meta-analysis of a sample of individuals of South Asian descent living in Canada (N-348) and the second study involving a sample of individuals from two caste and four tribal groups from West Maharashtra, India (N=480).
The meta-analysis also involved the first GWAS of iris color in South Asian populations. South Asia has a complex history of migrations and is characterized by substantial pigmentary and genetic diversity. For this reason, it is an ideal region for studying the genetic architecture of normal pigmentation variation. The current study identified genome-wide significant associations of variants within the well-known gene SLC24A5, including the nonsynonymous rs1426654 polymorphism, with both skin pigmentation and iris color, highlighting the pleiotropic effects of this gene on pigmentation. Variants in the HERC2 gene (e.g., rs12913832) were also associated with iris color and iris heterochromia. This study emphasizes the usefulness of quantitative methods in studying iris color variation. It also identified novel genome-wide significant associations with skin pigmentation and iris color, but the study could not replicate these associations due to the lack of independent samples. The authors advise that it is critical to expand the number of studies in South Asian populations in order to better understand the genetic variation driving the diversity of skin pigmentation and iris color observed in this region. (publisher abstract modified)
Report (Grant Sponsored)
Date Published: April 1, 2019