Dominant white/white spotting

Dominant White (W) and White Spotting (ws) are found across many breeds of cats and result from the insertion of a common “feline endogenous retrovirus” in the KIT gene. A full 7125bp insertion results in White Spotting while a partial insertion results in Dominant White. Only one copy of the full insertion is required for the White Spotting color pattern when the other allele is wild-type. While the extent of White Spotting is not definitively associated with copy number, anecdotal evidence suggests that two copies of the white spotting insert results in more white. The pattern of white spotting does not correlate with one or two copies and the gene/genes controlling the pattern of White Spotting remain unknown. Additionally, not all white spots or patterns result from these alleles as other genes can also have mutations that result in depigmentation phenotypes., One or two copies of the partial insert results in the Dominant White (DW) phenotype regardless of the other allele. Dominant White is distinct from albinism (C) which results from a mutation in a different gene that has no known impact on hearing. While one or two copies of the DW allele will result in a white cat, varying degrees of hearing impairment are observed. In an extended pedigree, nearly 75% of cats with two copies were deaf and the remainder had at least partial hearing impairment.