Lack of association between promoter polymorphisms of HLA-G gene and rheumatoid arthritis in Korean population.

The aim of this study was to determine whether the HLA-G gene was associated with susceptibility to rheumatoid arthritis (RA). Major histocompatibility complex, class I, G (HLA-G) is involved in immunoregulatory processes and particularly in pathogenesis of inflammatory disorders. To investigate possible association between HLA-G and RA, 296 RA patients and 468 healthy controls were enrolled in this study. Two-promoter single-nucleotide polymorphisms (SNPs) (rs1736936, -1202T/C and rs2735022, -586C/T) in HLA-G gene were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). For analysis of data, Helixtree software, SNPAnalyzer, SNPStats, and Haploview version 4.2 were used. Multiple logistic regression models (codominant, dominant, and recessive) were performed for odds ratio (OR), 95% confidence interval (CI), and P value. There were no significant differences in distributions of genotypes and haplotypes between RA patients and control subjects. In clinical features of RA, we found differences between C-reactive protein levels (≥0.5 or <0.5 mg/dL) and two-promoter SNPs. Rs1736936 was significant in codominant (P = 0.028, OR = 0.66, 95% CI = 0.45-0.96) and dominant (P = 0.046, OR = 0.58, 95% CI = 0.34-0.99) models. Also, rs2735022 was significant in codominant (P = 0.038, OR = 0.67, 95% CI = 0.46-0.98) and dominant (P = 0.03, OR = 0.55, 95% CI = 0.33-0.94) models. However, these significant associations disappear after Bonferroni correction. Our results suggest that HLA-G promoter polymorphisms may be not associated with the development of RA in Korean population.