Head spot and dilute mutations in the Norway rat

A mutant allele of a new white spotting locus in the Norway rat is described, which is designated as head spot (hs). The allele is inherited as a recessive to normal. The expression is regularly manifested and has the form of a white sport of variable size in the middle of the forehead just above the eyes. A probable reoccurrence of blue dilution coat color is also reported. Tests for genetic linkage for hs indicate that it is independent of the agouti, dilute, and hooded loci.