Programmed cell death 1 (PDCD-1, also named PD-1, CD279, and SLEB2), a negative T cell regulator to maintain peripheral tolerance, induces negative signals to T cells during interaction with its ligands and is therefore a candidate gene in the development of autoimmune diseases such as rheumatoid arthritis (RA). Herein, we investigate the association of PDCD-1 polymorphisms with the risk of RA among Iranian patients and healthy controls.
Genomic DNA was extracted from the whole blood samples using DNA Purification kit (DNG-plus). Using the PCR- RFLP method, 3 PDCD-1 SNPs, including PD1.1G/A, PD1.3G/A, and PD1.9C/T were genotyped in 120 RA patients as well as 188 healthy controls. The genotype and allele frequencies of these SNPs were analysed by statistical tests for the significant association between RA patients and controls. Haplotype constructions of these SNPs were performed. Clinical diagnosis of the RA patients was confirmed by the Rheumatology Research Centere of Tehran University of Medical Sciences.
Our study revealed that PD1.1 A allele at position -538 in the promoter region of PDCD-1 gene is associated with an increased risk of RA disease compared to controls (2.9% vs. 0.7%, OR= 3.735, 95% CI= 0.956-14.588, p=0.046). There were no significant differences in other alleles and genotypes of PDCD-1 SNPs between RA cases and controls.
Our results indicate that among the polymorphisms which we evaluated only the PD1.1A allele in the promoter region of PDCD-1 gene is significantly associated with RA susceptibility in Iranian patients.