Light skin of UVA can penetrate deeply into the dermis in persons with light skin pigmentation with little protective melanin pigment. The characteristic of fair skin, red hair, and freckling is associated with high amount of pheomelanin, little amounts of eumelanin. This phenotype is caused by a loss-of-function mutation in the melanocortin 1 receptor (MC1R) gene. However, variations in the MC1R gene sequence only have considerable influence on pigmentation in populations where red hair and extremely fair skin is prevalent. The gene variation’s primary effect is to promote eumelanin synthesis at the expense of pheomelanin synthesis, although this contributes to very little
White (horse) other white spotting genes. True white horses have unpigmented pink skin and unpigmented white hair, though eye color varies. The lack of pigment in the skin and hair is caused by the absence of pigment-producing cells called melanocytes. Some coat colors are characterized by light or white-like coats and even pinkish skin, however these white-like coats are not lacking melanocytes. Instead, white-like coat colors result from various changes in the ways melanocytes produce pigment. Gray horses have the most common "white-like" coat color. However, the most noticeable difference between a gray horse whose hair coat is completely white and a