Coat Colour I-Locus (Intensity)

The coat colour of dogs is determined by a complex interplay among various genes, collectively known as ‘loci’. One such locus is the I-Locus, also referred to as intensity dilution/intense (I) locus. This I-locus is linked to the gene MFSD12, which is responsible for pigment synthesis and distribution of pigment across the body. The mutation in this gene is autosomal recessive and the affected allele, labeled as i, causes a dilution of phaeomelanin (light pigment) in affected dogs, resulting in the lightening of yellow or red coats to cream or white. Conversely, the unaffected allele, denoted as I, leads to normal colouration.

Dogs with the genotype i/i show a lightened coat colour, often described as pale cream or white, provided they also carry the recessive variant of the E-Locus (e/e). It's important to note that these dogs are not albino and should maintain dark pigmentation on areas such as the lips, paw pads, and eye rims. Similarly, dogs with a black-and-tan or saddle tan colouration will exhibit a creamy coat instead of tan fur when affected by the I-Locus mutation.

Because research suggests that additional, unidentified genes can influence the expression of this mutation, the dog’s physical appearance may not always be predictable from its genetic results. In other words, the polygenic nature of pigmentation can lead to discrepancies between a dog’s genotype and its observed coat colour.

Pubmed ID: 31117290

Year published: 2019

Omia ID: 2197

Omia variant ID: