Genes affecting coat colour and the resulting variation in horses (Equus caballus) – A Review

Abstract

Horse colour is important. People chose horses for their colour pattern diversity, according to archaeological investigations and biological evidence. Horses were generally dark coloured before domestication, according to molecular testing. After domestication, the genes for white patterns and dilutions appeared. The appearance of their horses, as well as their competence and willingness to work, must have been important to early people. In many cases, the genes that impact coat colour patterns in one species also influence coat colour patterns in another. In horses, humans, cattle, dogs, and other species, the MC1R gene encodes the alleles for red and black of the Extension locus. White spotting is caused by mutations in the KIT gene in horses (tobiano, roan, sabino, dominant white), mice, and humans. Because of its similarity to a white hair gene seen in humans with Hirschprung's illness, the gene for overo in horses was discovered. The genes that impact coat colour patterns in one species generally play a similar role in another, according to molecular studies. It came as no surprise. Earlier geneticists claimed that coat colours in horses were caused by the action of genes similar to those observed in other species based solely on phenotype. This is a crucial lesson for genetic studies: we can apply what we have learned from other species to our own. All in all, the study of coat colour variations in the horse is a study of the horse's nature.