A team of scientists from Hyderabad-based Center for Science and Industrial Research-Center for Cellular and Molecular Biology (CSIR-CCMB) made new findings of genetic link to skin colour which is expected to further help the scientists to understand the link between genomic features, disease susceptibility and drug response. This will enable to make ground for developing personal and customized medicines for individual patients in future.
“This is yet another effort from the team of scientists at CSIR-CCMB in the field of genomics, which helped us in understanding the genetic link to the skin colour”, said Dr Rakesh Mishra, Director, Centre for Cellular and Molecular Biology. According to Dr. Mishra a team of scientists led by Dr. Kumarasamy Thangaraj at CCMB Hyderabad, in collaboration with Estonian Biocentre, Estonia and 5 other institutes had conducted an extensive research to explore the genetics of skin colour variations across India.
As part of the research, the team of scientists carried out extensive epidemiological survey of 1167 individuals belonging to 27 populations and quantified melanin content at most exposed and low exposed area of human body at Middle region of Gangatic plains (Uttar Pradesh and Bihar), and selected 374 individuals for the first round of genetic study. In their research it is found that SLC24A5 gene is known to make skin lighter and is the main reason behind 25-38 per cent of the pigmentation differences between Europeans and West Africans.
“Earlier it was established that a variant/modification (rs1426654) in the gene is associated with skin pigmentation measures in India. To understand it further the research team analysed the entire gene and found another variant (rs2470102), which contributes to skin pigmentation variation in Indian subcontinent. Further analyses revealed that both the variants (rs1426654 and rs2470102) together could better explain the variation in skin colour among Indian populations than considering each variant independently. The difference in skin colour persisted even when the contribution by the previously known SNP was adjusted, suggest that the new SNP has an independent effect on skin colour,” explained Dr. Anshuman Mishra, the first author of the study.
The scientists revealed that social structure defined by the caste system has a ‘profound influence on skin pigmentation’. The skin colour was found to vary significantly among ethnic groups and social categories studied. The researchers then compared the skin colour (phenotype) with the genetic variation (genotype) of the individuals. Those with derived (mutant) alleles had fairer skin compared to those who had old (wild type) alleles. “Our study clearly reflects the profound influence of the strict marriage patterns and multi-layered endogamy adding further to the variation in skin color contributing to the mosaic of skin tones” says Chandana Basu, one of the authors of the study and researcher at Estonian Biocentre, Tartu, Estonia.
Study was conducted on 1,825 individuals belonging to 52 diverse populations across India and found that, social category and associated SNPs explain 38.4 per cent of the variation in skin color. “Unlike Africans and Europeans, we do not have homogeneous skin colour throughout the country. This could be due to different waves of human migration into India and recent admixture of all Indian populations, which we predicted in our previous study that it could have happened about two thousand years ago,” said Dr Thangaraj.
Overall with these new findings of genetic mutations linking with skin colour scientists points to the era of personalized medicine based on link of genomic features with disease susceptibility and drug response. “We feel that more such studies be carried, at very large scale, to establish individual specific lifestyle advisory and medical prescriptions as it is clear that ‘one size does not suit all’ is also applicable to the area of human health and disease, opined Dr Mishra.
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