Association of MICA Alleles with Autoimmune Thyroid Disease in Korean Children

Background . Major histocompatibility complex class I chain-related gene A (MICA) is a ligand for the activating NKG2D receptor expressed on natural killer (NK) cells. We aimed to assess the association of MICA polymorphism with autoimmune thyroid disease (AITD) in Korean children. Methods . Eighty-one patients with AITD were recruited. We analyzed MICA polymorphisms by PCR-SSP and compared the results with those of 70 healthy controls. Results . In AITD, the allele frequencies of MICA∗010 (OR = 2.21; 95% CI, 1.30–3.76, P < 0.003, P c < 0.042) were higher than those of controls. Patients who did not have thyroid-associated ophthalmopathy showed higher frequencies of MICA∗010 (OR = 2.99; 95% CI, 1.47–6.08, P < 0.003, P c < 0.042) and lower frequencies of MICA∗008 (OR = 0.08; 95% CI, 0.01–0.62, P < 0.001, P c < 0.014) compared to those of controls. HLA-B∗46, which shows the strongest association with AITD compared with other HLA alleles, showed the strongest linkage disequilibrium with MICA∗010. Analyses of the associations between MICA∗010 and HLA-B∗46 with AITD suggest an association of the MICA allele with AITD. Conclusions . Our results suggest that innate immunity might contribute to the pathogenesis of AITD.