Genetic basis of A locus - also called the agouti locus, controls the distribution and type of pigment produced in mammals' hair follicles. It encodes the agouti signaling protein (ASIP) that regulates the switch between producing eumelanin (black or brown pigment) and phaeomelanin (red or yellow pigment). Specific alleles at the A locus determine the presence of agouti coloration by modulating the pattern and timing of pigment production by melanocytes.

Pathophysiology - The ASIP protein acts within hair follicles to direct melanocytes on whether to produce eumelanin or phaeomelanin. This regulation involves cell-cell communication and signaling pathways that influence pigment synthesis. Mutations or variations in the ASIP gene can alter pigment production patterns, leading to changes in coat coloration phenotype. Agouti mutations can also have pleiotropic effects beyond pigmentation, such as impacts on development, obesity, and susceptibility to certain diseases in animal models.

Why This Matters to Breeders and Vets - Understanding the agouti locus and its variants is crucial for accurate coat color prediction and selection in breeding programs. Genetic testing for A locus alleles allows breeders to make informed decisions about pairings to achieve desired coat colors.

Summary - The A locus agouti controls a fundamental pigment switch via the ASIP gene, influencing eumelanin and phaeomelanin distribution to produce distinctive coat color patterns like sable and tan point. Knowledge of the genetic basis and inheritance of agouti patterns is key for breeders to predict coat colors accurately.

Please Note: We strongly recommend that you also request a K-Locus test with any A-Locus request as the expression of any A locus results (colour) is stringly influenced by the K-Locus.