Association of FoxP3 promoter polymorphisms with the risk of Graves' disease in ethnic Kashmiri population

Graves' disease is a multifactorial autoimmune disorder of the thyroid gland, with some extra-thyroidal complications like eye and skin abnormalities in some patients. GD is more prevalent in women than men and is the leading cause of hyperthyroidism worldwide. A complex interaction between genetic and environmental factors is the proposed cause which triggers immune system to produce autoantibodies stimulating the TSH receptor, leading to clinical manifestations such as hyperthyroidism, diffuse thyroid enlargement (goiter) and often ophthalmopathy in affected individuals. Various Single nucleotide gene polymorphisms (SNPs) have been associated with the risk of GD development including promoter SNPs in Forkhead Box P3 (FOXP3). FOXP3 is an important regulatory factor for T cell development and differentiation and therefore has a prominent role in suppression of autoimmune reactions which may lead to predisposition of GD. There have been some studies on the association of FOXP3 SNPs with GD, but no such investigation has been carried out in ethnic Kashmiri population. So, we aimed to study a possible association of FOXP3 promoter SNPs (−3279C/A, −2383C/T & -3499 A/G) with GD. Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was used to genotype 285 individuals (135 GD cases and 150 healthy controls) and the results showed statistically significant differences in genotypic and allelic frequencies of cases and controls for −3279C/A SNP [OR, 3.48; 95% CI (2.05-5.92); P < 0.001] and −2383C/T SNP [OR, 5.62; 95% CI (2.43-13.00); P < 0.001], while no significant association was seen in case of −3499 A/G SNP. We conclude that −3279C/A and −2383C/T SNPs have a highly significant association with the risk of GD development in Kashmiri population.