A few more grains of melanin

The color of human skin is mainly determined by melanin synthesis, which takes place inside melanosomes of melanocytes, and the subsequent transfer of these pigment granules to keratinocytes. There is no difference between the races in the number of melanocytes in the epidermis,1 but the rate of melanin synthesis may be different. The ratio between eumelanin and pheomelanin synthesis is higher in black than in white people,2 but the most striking differences between black and white skin are the size of the melanosomes and the distribution pattern of melanosomes inside the keratinocytes. In black-skinned people, the large melanosomes are each surrounded by the membrane, whereas in brownand white-skinned people, the smaller melanosomes are grouped together in a single membrane.3 This phenomenon is probably caused by only one gene. We described an autosomal-dominant syndrome with white and dark macules, together with other symptoms, occurring in three generations of people with skin type V, which became known as the Westerhof syndrome. In each member, the dark and white macular skin resembled, at ultrastructural level, negroid and caucasoid skin, whereas the normal asiatic skin had features in between.4 Apart from the physionomy, the stature and the hair, the human skin color is one of the most important external features which distinguishes between races. Because of its simplicity and visibility, the discriminatory power of skin color is absolute and used by scientists and laymen.