Association of Rsa polymorphism of the estrogen receptor-β gene with rheumatoid arthritis

To investigate the possible influence of the single nucleotide polymorphism (SNP) of the estrogen receptor-β gene, rs1256049 (Rsa) in exon 5, on the frequency of rheumatoid arthritis (RA), 263 RA patients and 174 control subjects with osteoarthritis (OA) were recruited. Rsa polymorphism was detected using a PCR-RFLP, Polymerase Chain Reaction-Restriction Fragment Length Polymorphism method. The occurrence of both mutant allele (G) and genotype (GG) were significantly higher in RA than in OA patients (allele P = 0.008, OR: 1.501, 95%CI: 1.12-2.02). In RA patients, GG genotype frequency was higher in severe RA patients than mild RA patients. Moreover, there was significant difference between severe RA patients and OA patients (P = 0.009), also the allele distribution was significant different between severe RA, mild RA, and OA patients (P = 0.025, 95%CI = 0.61-0.93). With respect to gender, GG genotype was statistically more frequent in female RA patients than that of OA, while such an association was not observed in men. Above all, the presence of the GG genotype could be a risk factor for RA and such trend might be different in gender, although additional larger scale study is needed.