The human leukocyte antigen class II gene has different contributions to autoimmune Type 1 diabetes with or without autoimmune thyroid disease in the Japanese population

Abstract Aim Type 1 diabetes (T1D) is associated with autoimmune thyroid disease (AITD). The human leukocyte antigen (HLA) has been extensively studied in these diseases. We aimed to clarify the contribution of AITD on the susceptibility and resistance of the HLA subtype to autoimmune T1D in the Japanese population. Methods The frequency of the HLA DR-DQ haplotype was compared between 56 autoimmune T1D patients with AITD and 71 autoimmune T1D patients without AITD, and control subjects. Results The frequencies of DRB1*0405-DQB1*0401, DRB1*0802-DQB1*0302, and DRB1*0901-DQB1*0303 haplotypes were significantly higher in T1D patients with AITD than in control subjects. The frequencies of DRB1*0101-DQB1*0501, DRB1*0901-DQB1*0303, and DRB1*1302-DQB1*0604 haplotypes were significantly higher in T1D patients without AITD than in control subjects. The frequencies of DRB1*1101-DQB1*0301 and DRB1*1501-DQB1*0602 haplotypes were significantly lower in T1D patients with or without AITD than in control subjects. Conclusions Our results suggest that the susceptibility of the HLA subtype to autoimmune T1D differs between T1D with AITD and T1D without AITD, whereas there is no difference between the two groups with regard to HLA subtypes that confer protection against autoimmune T1D.