Co-dominant expression of MHC Antigens
Each individual expresses in a co-dominant fashion the class I and class II genes of both chroosomes 6. So each individual expresses 3 maternal and 3 paternal class Is (A, B, C), and 3 maternal and 3 paternal class IIs (DP, DQ, DR). Each individual has two "half sets" (haplotypes) of genes, one from each parent. both of these haplotypes are expressed equally.