Endothelial nitric oxide synthase T-786C polymorphism in rheumatoid arthritis: association with extraarticular manifestations.

Several genetic factors were implicated in the pathogenesis of rheumatoid arthritis (RA). A case-control study was carried out to verify the associations of T-786C polymorphism in the promoter region of the endothelial nitric oxide synthase (eNOS) gene with RA. One hundred and five consecutive RA patients and 100 healthy controls were genotyped. The distribution of the T-786C genotype and alleles did not differ significantly between RA patients and controls. Nevertheless, the frequency of extraarticular manifestations was significantly greater among the carriers of the C/C genotype than among carriers of the T/C and T/T genotypes (P = 0.022). The C/C genotype was significantly associated with extraarticular manifestations compared with the T/T and T/C genotypes taken together (OR = 4.9, 95% CI = 1.3-18.9). The C allele was significantly associated with extraarticular manifestations of RA (P(corr) = 0.032). The results suggested the existence of an association between the T-786C polymorphism of the eNOS gene and extraarticular manifestations of RA.