Seal Brown (horse) - Former Theories About The Genetics of Seal Brown - Tyrosinase-brown

Tyrosinase-brown

Tyrosinase-related protein 1 (TYRP1) is a protein involved in melanin synthesis, and is encoded by the TYRP1 gene, also called the brown (b) locus. In humans, mutations in the TYRP1 gene account for variations in "normal" skin, hair and eye coloration, as well as types of clinical Albinism. Mutations in the TYRP1 gene of other mammals result in various reddish-brown coat color phenotypes: Brown in mice, Chocolate in cats, Chocolate in dogs, and Dun in cattle.

The phenotypes associated with TYRP1 mutations are typically rufous or chocolate rather than the black-dominated coats of seal brown horses, and usually result in pinkish-brown skin and light eyes. This is not the case for seal brown horses, and the role of TYRP1 in seal brown was ruled out after it was sequenced in 2001.