Skin “color†is determined mainly by the type and amount of melanin deposited in the epidermis. Melanin is a large bio-polymer composed of subunits of different melanotic pigment species formed by sequential oxidation and cyclization of the amino acid tyrosine). Biosynthetic reactions are catalyzed by several pigment enzymes, which when defective, render hypopigmented phenotypes. Tyrosinase is the rate-limiting enzyme that catalyzes the first two steps in melanogenesis, namely conversion of tyrosine into DOPA and then subsequently into DOPAquinone . Loss of function of tyrosinase is the defect in the most common type of human albinism. In the skin, melanin is synthesized in melanocytes and then transferred to keratinocytes where it accumulates to protect the skin against UV injury. There are two basic types of melanin: eumelanin and pheomelanin.