Melanocytogenesis and melanogenesis: genetic regulation and comparative clinical diseases

Murine models recently provided important information on the pathogenesis o f pigmentation disorders. Multiple factors influence melanocyte function at various levels, such as melanoblast development and migration from the neu ral crest to peripheral sites, melanoblast differentiation into melanocytes , melanocyte survival and, finally, synthesis of melanosomes and melanins. Mutations affecting any of these steps result in hereditary hypomelanoses. In some of these diseases, melanocytes are absent, either because of a defe ct in migration of melanoblasts from the neural crest, their inability to s urvive and/or proliferate in colonized territories (piebaldism and Waardenb urg syndromes), or because of programmed melanocyte destruction (e.g. vitil igo). In other entities, the melanocytes are present but functionally defic ient (oculocutaneous albinisms and pigmentary dilutions). This comprehensiv e review will introduce the genetic regulation of melanocytogenesis and mel anogenesis and the correlations between genetic abnormalities and hypopigme ntation clinical disorders.