S-Locus (white spotting)

The S-Locus is a region of your dog's DNA which determines whether they will have any patches of white spotting or a largely white coat. The white coat is caused by hairs which lack both the phaeomelanin and the eumelanin pigment, this disrupts the pigment causing areas of white coat and pink skin.

Also known as flash, parti, piebald, or pied.

White spotting is an autosomal co-dominant condition caused by a mutation in the MITF gene. One copy of S can result in limited white spotting, anywhere from 0-50% coverage, whilst two copies of S can result in anywhere from 50-100% white coverage.

There are other mutation of the S-Locus such as Irish spotting and we only test for the most common which is relevant in all breeds. Mutations in the S-Locus have also been implicated in disorders of the eye and hearing.