HLA-DRB1 and major depressive disorder: genotyped HLA‐A, HLA‐B, HLA‐C, HLA‐DRB1, HLA‐DQB1, and HLA‐DPB1 in 136 Japanese patients with MDD and found that HLA‐DRB1*04:10 was a risk allele, whereas HLA‐DRB1*04:10‐HLA‐DQB1*04:02 was a risk haplotype for MMD.