Association of PD-1 (rs36084323) gene polymorphism with autoimmune thyroid diseases

Autoimmune thyroid disease (AITD) is among the most common autoimmune diseases, including Graves' disease (GD) and Hashimoto's thyroiditis (HT), but their pathophysiological mechanism isn't fully understood with multiple involved genetic factors. Programmed cell death-1 (PD-1) boosts the suppression of regulatory T cells. The promoter region polymorphism rs36084323 affected PD-1 gene transcription and activation in many cancer and autoimmune diseases. Genetic correlation between this polymorphism and AITD pathogenesis was evaluated in Egyptian patients & included: Group 1; fifty-five GD patients & forty five HT patients, Group 2; one hundred fifty controls by PCR-RFLP technique. GD patients showed significantly higher AG, AA, and A allele frequencies of the PD-1 rs36084323 gene than the control group with no significant disparities between HT patients and controls for any genotype or allele. When analyzing all AITD patients compared to control group, only the A allele showed higher frequency approaching statistical significance (p = 0.057). AA genotype and elevated free T4 were significant risk factors for GD, while elevated TSH was a significant protective factor for GD and a significant risk factor for HT. PD-1 rs36084323 polymorphism differs between GD and HT and is associated with higher risk of GD in Egyptian patients.