Most literature showed that main determinants of susceptibility, both in AIH and MS, may be specific MHC class alleles such as HLA-DRB1variants, which are involved in presenting peptides to CD4 T cells and regulation of their activation and impaired IL-2/IL-2RA signaling, which is pivotal for the maintenance of the ability of Treg to control autoreactive cells. The gene discussed is HLA-C; the disease is autoimmune hepatitis.