Background and aims The gene C-reactive protein (CRP), located at 1q23-24, is a candidate to be investigated as a susceptibility locus for systemic lupus erythematosus (SLE). The aim of the study was to evaluate the association between the +1444CT CRP polymorphism with the susceptibility for SLE, disease activity, and CRP serum levels.

Methods The study enrolled 176 SLE patients and 223 healthy controls from Brazilian population. SLE disease activity (SLEDAI), clinical and laboratorial characteristics were evaluated. The +1444CT CRP polymorphism was determined using polymerase chain reaction and restriction fragment length polymorphism.

Results The frequency of CC vs. TT genotypes and the C vs. T allele among the patients differed from the controls (p=0.0201 and p=0.0072, respectively). Patients carrying the T allele presented higher CRP (p=0.017) and showed a trend toward higher IL-6 compared with patients carrying the C allele (p=0.057). The increased CRP was independently of the IL-6 in these subgroups of patients. SLE patients carrying the CC genotype showed positive correlation between CRP and C4 levels (p=0.039), while those with T allele presented a trend toward a negative correlation between CRP and C3 and C4 (p=0.056 and p=0.073, respectively); and a trend toward positive correlation with anti-nucleosome and anti-dsDNA (p=0.052 and p=0.091, respectively).

Conclusions Our data showed that +1444CT CRP polymorphism was associated with SLE susceptibility and CRP levels, as well as CRP levels were associated with disease activity, suggesting that this polymorphism may play a role in the pathophysiology of SLE, which may be used as a possible marker of disease activity.