93 to 100% of samples of Sub-Saharan Africans, East Asians and Indigenous Americans. The variation is a SNP polymorphism rs1426654, which had been previously shown to be second among 3011 tabulated SNPs ranked as ancestry-informative markers. This single change in SLC24A5 explains between 25 and 38% of the difference in skin melanin index between peoples of sub-Saharan African and European ancestry. The SNP rs2470102 independently affects skin pigmentation variation among the South Asian population. Furthermore, the European mutation is associated with the largest region of diminished genetic variation in the CEU HapMap population, suggesting the possibility that the A111T mutation may be the subject of the single largest degree of selection in human populations of European ancestry. It is hypothesized that selection for the derived allele is based on the need for sunlight to produce the essential nutrient vitamin D. In northerly latitudes, where there is less sun, greater requirement for body coverage due to colder climate, and frequently, diets poor in vitamin D, making lighter skin more suitable for survival. The earliest known sample of the threonine allele is 13,000 years old from Satsurblia Cave in Georgia. The allele was widespread from Anatolia to Ukraine and Iran at the beginning of the Neolithic. This allele forms part of the HIrisplex DNA test system used to estimate pigmentation in forensic investigations. See also Human skin color SLC45A2 Tiger eye References Further reading External links Solute carrier family