The present study of a larger new cohort of Japanese patients with AIH confirmed that the HLA-DRB1*04:05 (Pc = 3.9×10−9) and DQB1*04:01 (Pc = 3.7×10−9) alleles and the DRB1*04:05-DQB1*04:01 haplotype (Pc = 2.3×10−10) are the principal susceptibility alleles for type 1 AIH. The gene discussed is HLA-DRB1; the disease is autoimmune hepatitis.