litter MC1R Agouti wild type alleles
Puppies of all colours can occur in the same litter. Coat colour is determined primarily by three genes, MC1R, Agouti and CBD103. If a dog carried wild type alleles at all three loci, the dog will have a yellow coat. If a dog has a loss-of-function mutation at MC1R, it will also have a yellow coat, regardless of their genotype at the other two loci. Dogs carrying wild-type alleles for MC1R and Agouti, together with the black allele of CBD103, will have a black coat.
