Molecular tests for horse coat color determination

Wild animals often have muted colors that allow them to blend into the background. During the domestication, people delight in selecting for color variants, so that domestic animals, including cats, dogs, cows, sheep, horses and goats exhibit a wide range of color patterns, even though they belong to the same species. The horse basic coat colors (chestnut, bay and black) are controlled by the interaction between two genes: Melanocortin-1-Receptor [MC1R; Extension (E,e)] and Agouti Signaling Protein [ASIP; Agouti (A,a)]. The Extension gene (red factor) controls the production of red and black pigment. Agouti controls the distribution of black pigment either to a point pattern (mane, tail, lower legs, ear rims) or uniformly over the body. Ten other genes may modify the distribution, production and quantity of these pigments and are responsible for the large variety of horse coat colors. Most of coat colors may be detected based on physical appearance or phenotype alone. The aim of this study is to develop molecular tests in order to define phenotypes that are visually ambiguous and identify the correct coat color phenotype for the four dilute phenotypes palomino, buckskin, cremello and perlino due to the effects of Membrane Associated Transporter Protein gene [MATP/SLC45A2; Cream (Cr,cr)] on basic colors. We demonstrate the effect of polymorphisms of MC1R, ASIP and MATP/SLC45A2 genes on 26 Akhal-Tekè horses bred in Italy with defined phenotypes bay, chestnut, black, buckskin, cremello and perlino. The 38.46% of horses tested, show a discrepancy between the phenotype reported on the certificate and the result of analyses carried out. On 11,54 % of the horses certificate is indicated any color. With the genetic analysis we can determine the correct genetic basis of the coat color and thus complete in a correct manner the certificate with the phenotype description.