Oculocutaneous albinism in Suncus murinus: establishment of a strain and identification of its responsible gene.

The house musk shrew Suncus murinus (Insectivora, Soricidae) is referred to as suncus in a laboratory context. Although the capture of albino-like shrews (wild suncus) has been reported previously, albino-like strains have never been established, and the molecular basis of the character has remained elusive. We have established an OCAO mutant strain (oculocutaneous albinism Okinawa), from a wild suncus with a white coat and red eyes, which was captured in 2002. During the course of establishing the strain, it was revealed that the albino-like phenotype was inherited in an autosomal recessive manner. To elucidate the molecular basis of this phenotype, we cloned the suncus cDNAs for tyrosinase (Tyr), pink-eyed dilution (p), and solute carrier family 45, member 2 (Slc45a2), since these genes are involved in oculocutaneous albinism in various species, including humans. Several polymorphisms were identified in these genes; however, linkage analysis excluded the involvement of Tyr and p. On the other hand, two amino acid substitutions (V240A and G366E) were identified in Slc45a2 that cosegregated with the phenotype in the OCAO mutant strain. While V240A was also present in colored suncus collected from Okinawa, G366E was unique to the albino-like suncus and heterozygous carriers. Thus, we conclude that a mutation in Slc45a2 (G366E) is responsible for an albino-like phenotype in Suncus murinus.