Europeans and some Indians share the same light skin gene mutation
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HYDERABAD: A scientific study of which a senior scientist of the Centre
for Cellular and Molecular Biology (CCMB) was the lead author has
thrown light on questions pertaining to the colour variations in human
populations.
An international team of scientists led by researchers from University of Tartu, Estonia, CSIR- Centre for Cellular and Molecular Biology (CCMB), Hyderabad India and University of Cambridge, UK have studied one of the most important pigmentation genes, SLC24A5 and published their findings on Thursday in PLoS Genetics.
Genetics studies done so far have helped in understanding the pigmentation genetics of Europeans to some extent, but South Asians, who represent wide range of skin color have so far been unexplored.
"We studied a homogeneous cohort of India and found that SLC24A5 gene explains most of the variation of the pigmentation extremes and has a major effect on pigmentation diversity. Our study also provides the first detailed map of the genetic variant and shows that the light skin associated genetic signature is wide spread in Indian subcontinent with substantial variation among different ethnic groups" said Dr K. Thangaraj, senior lead author from CCMB, Hyderabad.
Human skin color varies widely among and within populations and is a classic example of adaptive evolution. Pigmentation in humans is largely determined by the quantity and distribution of the biopolymer melanin, contained within melanosomes.
A significant correlation between skin color and ultraviolet radiation (UVR) levels observed at the global scale suggests that natural selection plays an important role in determining the distribution of this phenotypic trait.
The evolution of dark skin at low latitudes has been mainly accredited to the requirement of photo-protection against sunburn and skin cancer, whereas the evolution of light skin has been most commonly associated with vitamin D deficiency.
When human started moving to higher latitudes where ultraviolet radiation levels were lower, individuals with dark skin could not absorb sufficient ultraviolet radiation for efficient vitamin D synthesis, and thus natural selection favored the evolution of light skin.
"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" explained Chandana Basu Mallick, first author of the study published on Thursday from University of Tartu, Estonia and researcher at Estonian Biocentre.
Resequencing of 11.74 kb of SLC24A5gene using a global sample set have helped the researchers to unveil an important fact that Indians share the same mutation of SLC24A5for their light skin as Europeans and belong to the same haplotype background.
The study also provided the first comprehensive estimate of coalescence time of this genetic signature ranging 22-28 thousand years ago, which is crucial in the understanding of the evolutionary history of light skin in humans.
"The wide presence of the allele in India suggests that this allele was probably not a part of recent gene flow but existed in the sub-continent several thousand years ago" said Dr. Gyaneshwer Chaubey, co-author of this study and a researcher at Estonian Biocentre.
Apart from understanding the evolution of skin colour, this study when matured may have new insights into the proper use of cosmetics said Dr Ch Mohan Rao, director, CCMB.
An international team of scientists led by researchers from University of Tartu, Estonia, CSIR- Centre for Cellular and Molecular Biology (CCMB), Hyderabad India and University of Cambridge, UK have studied one of the most important pigmentation genes, SLC24A5 and published their findings on Thursday in PLoS Genetics.
Genetics studies done so far have helped in understanding the pigmentation genetics of Europeans to some extent, but South Asians, who represent wide range of skin color have so far been unexplored.
"We studied a homogeneous cohort of India and found that SLC24A5 gene explains most of the variation of the pigmentation extremes and has a major effect on pigmentation diversity. Our study also provides the first detailed map of the genetic variant and shows that the light skin associated genetic signature is wide spread in Indian subcontinent with substantial variation among different ethnic groups" said Dr K. Thangaraj, senior lead author from CCMB, Hyderabad.
Human skin color varies widely among and within populations and is a classic example of adaptive evolution. Pigmentation in humans is largely determined by the quantity and distribution of the biopolymer melanin, contained within melanosomes.
A significant correlation between skin color and ultraviolet radiation (UVR) levels observed at the global scale suggests that natural selection plays an important role in determining the distribution of this phenotypic trait.
The evolution of dark skin at low latitudes has been mainly accredited to the requirement of photo-protection against sunburn and skin cancer, whereas the evolution of light skin has been most commonly associated with vitamin D deficiency.
When human started moving to higher latitudes where ultraviolet radiation levels were lower, individuals with dark skin could not absorb sufficient ultraviolet radiation for efficient vitamin D synthesis, and thus natural selection favored the evolution of light skin.
"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" explained Chandana Basu Mallick, first author of the study published on Thursday from University of Tartu, Estonia and researcher at Estonian Biocentre.
Resequencing of 11.74 kb of SLC24A5gene using a global sample set have helped the researchers to unveil an important fact that Indians share the same mutation of SLC24A5for their light skin as Europeans and belong to the same haplotype background.
The study also provided the first comprehensive estimate of coalescence time of this genetic signature ranging 22-28 thousand years ago, which is crucial in the understanding of the evolutionary history of light skin in humans.
"The wide presence of the allele in India suggests that this allele was probably not a part of recent gene flow but existed in the sub-continent several thousand years ago" said Dr. Gyaneshwer Chaubey, co-author of this study and a researcher at Estonian Biocentre.
Apart from understanding the evolution of skin colour, this study when matured may have new insights into the proper use of cosmetics said Dr Ch Mohan Rao, director, CCMB.
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