[MIM*142560] system designation for the major histocompatibility complex gene products of at least four linked loci (A, B, C, and D) and a number of subloci on the sixth human chromosome that have been shown to have a strong influence on human allotransplantation, transfusions in refractory patients, immune responsiveness to certain antigens, and certain disease associations; autosomal dominant inheritance.major histocompatibility complex