THE ORIGINAL PINK-EYED DILUTION MUTATION-(P) AROSE IN ASIATIC MICE - IMPLICATIONS FOR THE H4 MINOR HISTOCOMPATIBILITY ANTIGEN, MYOD1 REGULATION AND THE ORIGIN OF INBRED STRAINS

Allelic variation of the mouse pink-eyed dilution ( p) gene in common laboratory strains and wild mice was examined by Southern blot and by polymerase chain reaction. In these assays the original p mutation all ele found in strains SJL/J, 129/J, B10.129(21m), P/J and FS/Ei most cl osely matches an Asian Mus musculus allele, confirming anecdotal accou nts of the Asian origin of this mutation. In contrast, the wild-type a llele found in other common laboratory strains was apparently derived from Mus domesticus. Analysis of chromosome 7 loci both proximal and d istal to the p locus demonstrates that strains SJL/J, 129/J, B10.129(2 1M), P/J and FS/Ei contain DNA segments of varying length derived from M. musculus. Strains 129/J and B10.129(21M) contain the largest segme nt of M. musculus-derived DNA (about 5 cM), including the loci Myod1, p, three clustered GABA(A) receptor subunit loci (Gabrg3, Gabra5 and G abrb3), and Snrpn. The difference in the species origin of genes from this region of chromosome 7 may underlie the basis of the antigenicity of the minor histocompatibility antigen H4, defined by the strain B10 .129(21M), and may account for the enhanced Myod1 activity observed in SJL/J mice.