Piebaldism, Waardenburg syndrome, and related disorders of melanocyte development.

Recent years have seen the identification of a complex network of interacting genes that regulates embryonic development of melanocytes, and many different genetic disorders of melanocyte development of both humans and the laboratory mouse have now been associated with abnormalities of these regulatory genes. Disorders of melanocyte development are characterized by heterogeneous distribution of pigmentation, so-called 'white spotting,' typified by piebaldism and Waardenburg syndrome. It is now clear that these disorders of pigment cell development represent a subgroup of the neurocristopathies, involving defects of various neural crest cell lineages that include melanocytes, but also involving many other tissues derived from the neural crest.