<P> MHC alleles are expressed in codominant fashion . This means the alleles (variants) inherited from both parents are expressed equally: </P> <Ul> <Li> Each person carries 2 alleles of each of the 3 class - I genes, (HLA - A, HLA - B and HLA - C), and so can express six different types of MHC - I (see figure). </Li> <Li> In the class - II locus, each person inherits a pair of HLA - DP genes (DPA1 and DPB1, which encode α and β chains), a couple of genes HLA - DQ (DQA1 and DQB1, for α and β chains), one gene HLA - DRα (DRA1), and one or more genes HLA - DRβ (DRB1 and DRB3, - 4 or - 5). That means that one heterozygous individual can inherit six or eight functioning class - II alleles, three or more from each parent . The role of DQA2 or DQB2 is not verified . The DRB2, DRB6, DRB7, DRB8 and DRB9 are pseudogenes . </Li> </Ul> <Li> Each person carries 2 alleles of each of the 3 class - I genes, (HLA - A, HLA - B and HLA - C), and so can express six different types of MHC - I (see figure). </Li> <Li> In the class - II locus, each person inherits a pair of HLA - DP genes (DPA1 and DPB1, which encode α and β chains), a couple of genes HLA - DQ (DQA1 and DQB1, for α and β chains), one gene HLA - DRα (DRA1), and one or more genes HLA - DRβ (DRB1 and DRB3, - 4 or - 5). That means that one heterozygous individual can inherit six or eight functioning class - II alleles, three or more from each parent . The role of DQA2 or DQB2 is not verified . The DRB2, DRB6, DRB7, DRB8 and DRB9 are pseudogenes . </Li>

How does the healthy human immune system use mhc markers