The Hum Genet (Journal of Human Genetics) article "A Global View of OCA2-HERC2 Region and Pigmentation" (OCA2-HERC2 Gene and Pigmentation from a Global Perspective) reveals blue color of Europeans. Both eyes and fair skin in East Asians are determined by a mutation in OCA2-HERC2 gene.
1. Object of study
The dissertation was attended by 3432 people from 73 groups distributed around world, including CHT (Chinese Taiwan), CHS (Chinese from San Francisco), HKA (Chinese Hakka), MNC (Chinese Manchu), HMG (Chinese Miao ) etc. . As shown below
2. OCA2-HERC2 gene
The OCA2-HERC2 gene has following important SNP segments, rs1800414, rs1800407, BEH1, BEH2, BEH3, as shown in figure:
Third, light-skinned East Asian gene
The rs1800414 gene in OCA2-HERC2 gene causes fair skin color in East Asians.
The distribution in world of 0-76% is as follows: specifically 62-76.1% in East Asia, 0-54.3% in Southeast Asia, 15.5-37.5% in Western China, only Circassians, Chuvashs, Chuvashs, Hungarians and Hungarians are common in Europe (1-3.6%), Yakut Yakuts are also common in Siberia (8.8%) and Micronesians of Micronesia in Oceania (4.2%), with largest proportion being 76, 1% CHT (Chinese Taiwanese).
His plot and distribution histogram look like this:
Fourth, genetic basis of European blue eyes
RS1800407, BEH1, BEH2 and BEH3 under OCA2-HERC2 gene all affect appearance of blue eyes.
Where rs1800407 is replaced with C→T, blue eyes may appear directly. This gene is very rare in world, common in Europe (0-11%), Western Asia (0-9.4%), Central Asia (0-9.3%), East Asia and Africa, this gene is absent at all, but in Arizona Pima (1.0%) and Maya (3.9%) Native Americans represent this gene.
According to description, less than 10% of blue-eyed people in world are caused by rs1800407.
Bluer eyes are caused by mutations in BEH1, BEH2, and BEH3 gene segments. However, carriers must mutate BEH1, BEH2, and BEH3 at same time to have blue eyes.
In terms of global distribution, BEH1 and BEH3 are found all over world, but BEH2 is found almost exclusively in Europe, so there are a certain number of people with blue eyes in this area.
The distribution looks like this: blue is BEH1, yellow is BEH2, red is BEH3.