Human Leukocyte Antigen (HLA) Genotypes and Thyroid Autoimmunity in Korean Patients with Type 1 Diabetes

Kang, So Young; Shin, Chung Ho; Yang, Sei Won; Park, Myoung Hee; Yu, Jeesuk

Abstract

PURPOSE
This study analyzed the expression of HLA-DR and DQ genotypes and anti-thyroid autoantibodies[anti-thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibodies] in Korean patients with type 1 diabetes (T1DM) to investigate the susceptible HLA alleles to T1DM in Korea and the prevalence of thyroid autoantibodies and their significance for the development of thyroid disorders. METHODS: A total of 59 Korean patients with type 1 diabetes[26 males, median age 13.7 years (range 5.7-29.9 years), diabetes duration 7.6 years (-1.7-22.5 years) ] were enrolled in this study, and 200 healthy Koreans without a family history of diabetes were selected as a normal control for the comparison of HLA genotypes. Seventeen patients with anti-TPO or anti-TG were followed [median duration 3.96 years (1 day-10.7 years) ] with measurement of anti-TPO, anti-TG, T3, T4 or free T4, TSH levels and physical examinations. HLA-DR and DQ genotyping were done by PCR-SSO, PCR- SSCP, PCR-RFLP and PCR-SSP methods. RESULTS: HLA analysis showed higher frequencies of HLA-DRB1*0301, *090102 and DQB1 *0201, *030302 alleles, DRB1*0301/*090102, *090102/*090102 and DQB1 *0201/*030302, *030302/*030302, *0201/*0302 genotypes in T1DM patients compared to controls (Pc< 0.05). Fifteen (25.4 percent) had anti- TPO antibody, 12 (20.3 percent) had anti-TG, 17 (28.8 percent) had either autoantibody and 10 (16.9 percent) had both autoantibodies. No clinical or subclinical hypothyroidism developed during follow- up after the first detection of anti-thyroid autoantibody. There was no significant correlation between thyroid autoimmunity and gender, onset age of T1DM, and diabetes duration, respectively (P> 0.05). CONCLUSION: We thought this unique HLA-DR, DQ allele distribution might be an important factor for the low incidence of T1DM in Korea. And a high prevalence of thyroid autoantibodies in these populations suggests examinations of thyroid antibodies should be performed regularly. Optimal age for the initial screening and the frequency of re-screening for associated thyroid autoimmune diseases in T1DM remains to be determined through prospective follow-up.