The role of PD-1 gene promoteric allele A in rheumatoid arthritis in Iranian patients

Programmed death 1 (PDCD1), a negative T-cell regulator which induces peripheral tolerance, belongs to Ig super and CD28/CTLA-4 families. PD-1 gene induces negative signals in T-cells during interaction with its ligands. Thus the aim of this study was to investigate the relationship between PD-1 polymorphism and the risk of rheumatoid arthritis (RA) in Iranian patients and healthy controls.

In this case-control study, genomic DNA was extracted from the whole blood samples using DNA purification kit (DNG-plus, Cinnagen, Iran). PD1.1G/A as a SNP located on promoter with position -536 were genotyped for 120 RA patients and 188 healthy controls through PCR-RFLP method. Association of genotypes and alleles frequency in the patients was compared with controls and analyzed using Chi-square test and 2×2 contingency table in SPSS software version 15.0. The diagnosis of RA patients and provision of their clinical information was done in Rheumatology Research Center of Tehran University of Medical Sciences, Tehran, Iran.

The A allele of the PD1.1 polymorphism located on the promoter of PD-1 gene was significantly more frequent in Iranian RA patients than the controls (p=0.04). There were no significant differences in PD1.1G/G genotype (p=0.08), PD1.1A/A genotype (p=0.39), and PD1.1G/A genotype (p=0.16) between RA cases and controls.

The findings of this study showed the presence of a significant relationship between the A allele of the PD1.1 (-536) of the promoter and susceptibility to RA in Iranian patients.