Test Detail

Genetic test for the canine S locus (white spotting), based on a SINE insertion in the regulatory region of the MITF gene. It determines whether the animal carries the sp allele (piebald/spotting) responsible for irregular white on the chest, limbs and forehead. In the Labrador retriever it reports on the minor white on the chest and toes, a common phenotype considered acceptable under the breed standard. It is not a disease test.

Applicable breed: Labrador retriever. Minor chest/leg white is a common phenotype in the breed, and the sp allele is widely distributed; there are no reliable published frequency figures for large series. The sp insertion appears in numerous dog breeds with spotting patterns.

- Genotype breeding dogs at the S locus if the standard or the kennel restricts white\n- sp/sp tends to produce more white: assess the mating according to the coat goal\n- S/sp with S/S produces predominantly solid offspring with some minor white\n- Remember that the actual amount of white is modulated by many additional genes, not only MITF\n- Do not prioritise the absence of white over health or temperament criteria

The MITF result predicts a tendency, not the exact percentage of white. The 'Irish spotting' pattern (white cross, collar, feet) interacts with other untested modifiers. In breeds with a restrictive white standard (such as the Labrador, where excessive white is penalised), the test helps plan matings, but phenotypic assessment remains the reference. Do not extrapolate the result to health.

1. Karlsson EK et al. (2007) Efficient mapping of mendelian traits in dogs through genome-wide association. Nat Genet 39:1321-1328. PMID: 17906626
2. OMIA:000214-9615 — Coat colour, white spotting (MITF) in Canis lupus familiaris (dog).
3. (Contexto sordera) Strain GM (2015) The Genetics of Deafness in Domestic Animals. Front Vet Sci 2:29. PMID: 26664958