Analysis of the Kit and Pdgfra genes in the patch-extended (Phe) mutation.

The patch (Ph) locus allele, patch-extended (Phe), has significantly less pigmentation than the original mutation and homozygotes have been known to survive to term. Analysing intersubspecific F1 hybrids, we were able to demonstrate that Phe is a deletional mutation encompassing the platelet-derived growth factor receptor alpha subunit (Pdgfra). The deletion does not appear to extend into the coding sequence of the Kit gene (a related tyrosine kinase receptor). However, we were able to demonstrate that, while the Kit gene is transcribed, it does not encode a functionally active receptor.