This does not take into account the effects of epistasis, which would probably increase the number of related genes.[58] Variations in the SLC24A5 gene account for 20–25% of the variation between dark and light skinned populations of Africa,[59] and appear to have arisen as recently as within the last 10,000 years.[60] The Ala111Thr or rs1426654 polymorphism in the coding region of the SLC24A5 gene reaches fixation in Europe, and is also common among populations in North Africa, the Horn of Africa, West Asia, Central Asia and South Asia.[61][62][63]