HLA-DQ polymorphisms modify the risk of thyroid autoimmunity in children with type 1 diabetes mellitus

Objective: Type 1 diabetes mellitus (DMI) is frequently accompanied by thyroid auto-immunity (TAI). The aims of the present study were to estimate the prevalence of TAI and to determine the contribution of HLA-DQA1 and -DQB1 polymorphisms to TAI susceptibility among children with DM1. Patients and Methods: Screening for TAI was performed in 285 children with DMI by measuring autoantibodies against thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg). HLA-DQA1 and -DQB1 were genotyped using PCR-SSP. Results: Repeated positivity of anti-TPO and/or anti-Tg was found in 45/285 children with DMI (15.8%). The prevalence was significantly higher in girls than in boys (26.7% vs 6.7%; p <10(-5)). The HLA-DQB1*0302 allele conferred susceptibility to TAI in children with DMI (OR 2.7, 95% CI 1.1-6.4), while the DQB1*05 alleles acted protectively (OR 0.2, CI 95% 0.08-0.7). Conclusions: HLA-DQ polymorphisms significantly modify the risk of TAI in children with DM1.