Executive Summary : | Humans are "colourful primates" with a vast diversity of skin, eye, and hair colors. Iris pigmentation, a highly heritable and polygenic trait, is found globally, with populations in Europe, parts of North Africa, Middle East, Central Asia, and south Asia exhibiting light blue to green to brown eyes. This diversity is important for anthropological research, forensic DNA phenotyping, and ophthalmology. Iris colour is determined by melanin content, light absorption, and Tyndall scattering. Genome-wide association studies have identified over sixty genetic loci associated with this phenotype. However, the diversity of iris colour and its genetics is relatively unexplored among south Asians.
This project aims to quantitatively characterize iris pigmentation among three populations from Maharashtra (Kokanastha Brahmins, Banjara, Andh), correlate skin and iris pigmentation measures, and test for association between ten iris colour candidate sNPs and quantitatively assessed iris pigmentation. High-resolution iris photographs, skin pigmentation (Melanin Index, MI), and a whole blood sample will be collected from consenting participants. sNPs will be genotyped using a Kompetitive allele specific PCR assay, and correlation coefficients between MI measures and iris colour will be computed. Association between genotypes and iris colour measures will be tested using linear and multiple regression under an additive model with age, sex, MI, and population as covariates. statistical analysis will be performed using program R v.4.2.1. This project will help characterize diversity in iris pigmentation and associated sNPs among indigenous Indian populations, providing baseline data for anthropological, forensic, and ophthalmological research. |