The coat colour chocolate/cinnamon can cause all black pigment to change to a brown colour that...plus
The Brown (tyrosinase-related protein-1, TYRP1) gene affects the amount of black (eumelanin) pigment produced. The coat colours chocolate and cinnamon are caused by mutations in the gene TYRP1 (tyrosinase-related protein 1) The wild-type B allele produces normal, black coloration. The b allele produces the brown (chocolate) phenotype and the bl allele produces a light brown or cinnamon phenotype. The brown variants show a suggested allelic series, with the following dominance pattern: B > b > bl. The B allele is dominant and represents the normal wild type black coat colour. Cats with brown genotypes bb or bbl have a chocolate phenotype, whereas cats with the light brown genotype blbl have a cinnamon phenotype.