Skin colour variation in Indians linked to genetic diversity

Washington - An international team of scientists took skin colour measurements from local residents in India to quantify the range and extent of variation in skin pigmentation phenotype and found that one of the important pigmentation genes; SLC24A5, plays a key role in skin pigmentation variation among South Asians. The comprehensive map of the genetic variant associated with light skin further revealed that it is quite wide spread in the subcontinent. “It was interesting to see that the effect of geographical, linguistic, socio-cultural boundaries further shaped by strict endogamy which forms the backbone of the South Asian genetic diversity was so strongly reflected in the complex patterning of this light skin allele,” Chandana Basu Mallick, lead author from University of Tartu, Estonia explained. She said that this study helps in understanding the other possible mechanisms that could have contributed in shaping the existing biological spectrum of human skin colour besides natural selection driven by UV rays and in further understanding of this complex phenotypic trait. Another element of the study involved resequencing of SLC24A5 using diverse set of samples which helped to unveil an important fact; that Indians share the same mutation of SLC24A5 for their light skin as Europeans and belong to the same haplotype background. Mircea Iliescu, co-lead author from the University of Cambridge said that the variable presence of this light skin mutation across India suggests an intriguing interplay between the forces of natural selection and the unique demographic history and structure of the populations inhabiting the Indian subcontinent. This study also provides the first comprehensive estimate of the coalescence time of this allele, which is crucial in the understanding of the evolutionary history of light skin in humans. The study is published in PloS Genetics.