Association of Interleukin 17 Polymorphisms and IL17A Levels with Papillary Thyroid Carcinoma: A Hospital-Based Study in the Chinese Population

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, and inflammation and immune dysregulation contribute to its pathogenesis. Interleukin (IL)17A’s role has been demonstrated in PTC. Genetic variants in IL17A may affect susceptibility and progression; however, their impact in the Chinese population remains insufficiently understood. This hospital-based case–control study included 272 patients with PTC and 250 age/sex-matched controls. Four IL17A single-nucleotide polymorphisms—rs2275913, rs3748067, rs8193036, and rs3819024—were genotyped using TaqMan assays. IL17A plasma levels were measured by ELISA. Allele, genotype, and haplotype distribution among controls and patients, and IL17 variant associations with IL17A levels were analyzed using GraphPad Prism. The rs2275913 AA genotype and minor allele showed a higher frequency in patients with PTC compared to controls, indicating an increased risk of PTC (AA: odds ratio OR = 1.88, 95% confidence intervals CI = 1.17–2.95, P = 0.01; A: OR = 1.44, 95% CI = 1.12–1.84, P = 0.003). Patients with PTC had higher plasma IL17A levels than controls ( P < 0.0001). IL17A genotypes, particularly rs2275913 AA, were associated with higher plasma IL17A concentrations. Genetic polymorphisms in IL17A (rs2275913) and elevated plasma IL17A levels correlate with PTC susceptibility in the Chinese cohort. These findings suggest IL17A’s potential as a biomarker for risk stratification and highlight inflammatory pathways in PTC pathogenesis.