Background: To date, studies have shown that polymorphisms in an autophagy-related gene, IRGM, are linked with different diseases, especially autoimmune diseases. The present study aimed to examine the roles of IRGM polymorphisms in autoimmune thyroid diseases (AITD).
Methods: Three polymorphisms in IRGM gene (rs10065172, rs4958847, and rs13361189) were genotyped in 1569 participants (488 with Graves' disease, 292 with Hashimoto's thyroiditis, and 789 healthy controls) using PCR-based ligase detection reaction method. Gene-disease associations were evaluated for the three SNPs.
Results: T allele of rs10065172, A allele of rs4958847, and C allele of rs13361189 were all higher in Graves' disease patients than controls, and the ORs were OR = 1.207 (P = 0.022), OR = 1.207 (P = 0.027), and OR = 1.200 (P = 0.027), respectively. After adjusting for sex and age, rs10065172 and rs13361189 were still associated with GD under both the allele model and dominant model, and the adjusted ORs for rs10065172 were 1.20 (P = 0.033) and 1.33 (P = 0.024), while the adjusted ORs for rs13361189 were 1.19 (P = 0.042) and 1.33 (P = 0.026), respectively. No significant difference was found between Hashimoto's thyroiditis patients and controls. Haplotype analysis found that CTA frequency was distinguishingly higher in Graves' disease patients (OR = 1.195, P = 0.030). The frequency of TCG haplotype was distinguishingly lower in AITD and Graves' disease patients (OR = 0.861, P = 0.044; OR = 0.816, P = 0.017).
Conclusions: Our study reveals IRGM as a susceptibility gene of AITD and Graves' disease for the first time.