Programmed death-1 gene polymorphism (PD-1.5 C/T) is associated with gastric cancer

This study aimed to determine the association between PD-1.5C/T (rs2227981, +7785) and the risk of gastric cancer (GC) in an Iranian population. Gastric cancer is the fourth most common cancer in the world. The programmed death 1 (PD-1) is a member of the CD28 super family. PD-1 is a negative regulator of T-cell effector mechanisms which decrease immune responses against cancer. Patients and we conducted case- control study to investigate the association of PD-1.5 C/T polymorphism in 122 GC patients and 166 control individuals. DNA was extracted from blood specimens. Genotypes were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The frequency of CC, CT and TT genotypes was 53.6%, 42.2% and 4.2% in control group and 41%, 54.1% and 4.9% in gastric cancer patients respectively. CC genotype was more frequent in control individuals than in patients but we found no statically significant association. The frequencies of PD-1.5CT genotypes were significantly higher in GC patient compared with control individuals (OR= 1.77, 95% CI= 1.077-2.931; P=0.026). Allele distribution was similar in patients and healthy individuals (p=0.061).Frequency of C and T alleles was 74.7%, 25.3% in control individuals and 68.03% and 31.97% in gastric cancer patients respectively. These results suggest that PD-1.5 C/T polymorphism may affect the GC risk and prognosis in an Iranian population.