Programmed cell death 1 gene polymorphisms is associated with ankylosing spondylitis in Chinese Han population.

Programmed cell death 1 (PD-1) has been reported to have a genetic association in several autoimmune diseases. The aim of this study was to investigate the association of PD-1 polymorphisms and haplotypes with ankylosing spondylitis (AS) in Chinese Han population. In a case-control association study, three single-nucleotide polymorphisms (SNP), PD-1.3 G/A, PD-1.5 C/T and PD-1.9 T/C, were genotyped in 216 AS patients and 264 healthy controls using polymerase chain reaction-restriction fragment length polymorphism assay. All genotype distributions in the patients and in the controls were in Hardy-Weinberg equilibrium. The associations of genotypes and alleles with AS were analyzed. The genotype distributions of PD-1.9 were significantly different between the patients with AS and the controls (P = 0.025). The frequencies of TC genotype and T allele of PD-1.9 were higher in the patients than those in the controls (P = 0.026 and 0.004). No association for PD-1.5 in AS was found, and PD-1.3 was non-polymorphic in Chinese Han population. Moreover, the frequency of the CT haplotype (PD-1.5 C/T, PD-1.9 T/C) was significantly higher in AS patients than the controls (21.6 vs. 13.9%, P = 0.002). The CC haplotype was more common in the controls than in the patients (57.1 vs. 44.6%, P = 0.000). The results support a genetic association between the PD-1 polymorphism and susceptibility to AS in Chinese Han population.