Objective: To investigate the relationship of gene polymorphisms of programmed cell death 1 gene (PDCD1) and ultraviolet history with systemic lupus erythematosus (SLE) among the Han population in the southern region of yangtze river in China.
Methods: With a case control design, a total of 159 SLE cases and 159 controls were enrolled in this study, and single nucleotide polymorphisms (SNPs) of the PDCD1 gene were determined by PCR-restriction fragment length polymorphism (RFLP). With the aid of the logistic regression model, the effect of gene polymorphism, environmental factor and the interaction between gene and environment were fitted under the recessive, dominant, additive and codominant mode, respectively.
Results: Three models were screened as the optimal models under the additive mode and one model under the dominant mode, according to the lowest value of Akaike's Information Criteria (AIC). After the control of age and gender, it was found that the frequency of ultraviolet exposure was higher in cases than in controls with significant difference under all models (P<0.05). For the haplotypes composed of the alleles of PD1.2, PD1.5 and PD1.6, there was significantly higher frequency of G-T-A haplotype (0.1196 vs 0.0363) and lower frequency of A-C-A haplotype (0.4746 vs 0.5399) in cases than that in controls (P<0.05) under the additive mode, and the G-T-A haplotype was associated with an increased risk for SLE (OR=4.319), while A-C-A haplotype was shown as a protective factor for SLE (OR=0.571). Moreover, interaction between A-C-G haplotype and ultraviolet exposure, which was related to an increased risk for SLE (beta5=1.182, Z=2.2898, P<0.05, OR=3.261), was also found under this mode. Additionally, the frequency of G-C-G haplotype was higher in cases than that in controls (0.1287 vs 0.0361) under the dominant mode with statistically significant difference (P<0.05, OR=4.332).
Conclusion: Authors' results indicate that ultraviolet exposure, G-T-A or G-C-G haplotype and interaction between A-C-G and ultraviolet exposure may be associated with genetic susceptibility to SLE in Han population in the southern region of yangtze river in China under certain genetic modes.