A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism

The mouse pink-eyed dilution ( locus on chromosome 7 is associated with defects of skin, eye and coat pigmentation Mutations at cause a reduction of eumelanin (black-brown) pigment and altered morphology of black pigment granules (eumelano-somes), but have little effect on pheomelanin (yellow-red) pigment We show here that the human complementary DNA linked to thelocus in mice identifies the human homologue ( of the mouse ene, and appears to encode an integral membrane transporter protein. The expression pattern of this gene in various mutant mice correlates with the pigmentation phenotype; moreover, an abnormally sized messenger RNA is detected in one mutant,un, which reverts to the normal size in un revertants. The human gene corresponds to the ocus within the chromosome segment 15qll-ql3, which is typically deleted in patients with Prader-Willi and Angelman syndrome (see ref. 5 for review). These disorders are phenotypically distinct, depending on the parent of origin of the deleted chromosome but both syndromes are often associated with hypopigmentation of the skin, hair and eyes (see ref. 8 for review), and deletion of thegene may be esponsible for this hypopigmentation. In addition, we report a mutation in both copies of the human gene in one case of tyrosinase-positive (type II) oculocutaneous albinism, recently linked to 15qll-ql3 (ref. 9).