Incomplete Dominance of ASIP Alleles in Hungarian Puli Dogs is Associated with MC1R Mutation

Abstract

Alleles of ASIP gene (Agouti locus) in dogs determine a wide spectrum of coat colors, from red to black. Gain-of-function Ay allele is the most dominant in the range of known ASIP mutations: when all other genes affecting coat pigmentation are intact, presence of Ay allele results in red coat color. Loss-of-function a allele is the most recessive allele of this gene. When homozygous, it gives black coat color. Usually, dogs with Ay/a genotype have red coat, because a single copy of Ay allele is sufficient to fully compensate for the non-functional allele a, implying the complete dominance in this pair of alleles. However exceptions are known. In the Hungarian Puli breed there is a specific coat pigmentation type called fako. We investigated the genetic composition of fako dogs and found evidence that the dominance of the Ay allele over the a allele may be incomplete in these dogs. Analysis of the MC1R gene that interacts with ASIP in the hair pigmentation genetic cascade allowed us to find the variants that may be responsible for the incomplete dominance of Ay allele over a allele in Hungarian Puli dogs.