Interleukin-6 promoter polymorphisms −174 G/C in Brazilian patients with systemic lupus erythematosus

To investigate the association of the IL-6 gene promoter polymorphism (−174 G/C) with SLE susceptibility and disease features in Brazilian patients, a case-control study of 80 lupus cases and 60 volunteer healthy women was performed. Genotyping was carried out by polymerase chain reaction and PCR product was digested by HSP92II restriction enzyme, being after visualized in polyacrylamide gel. There were significant differences in the distribution of the IL-6 gene C/C polymorphism between the SLE and control groups (χ2 = 8.668; P = 0.0032). Individual carriers of the variant allele G had a 1.98 (95% CI: 1.0844-3.6353)-fold increased risk for SLE. Besides, association was observed in frequency of C allele (P = 0.0247; OR = 0.5036) between SLE patients and control groups. This study presents preliminary evidence for association between IL-6 polymorphism and SLE susceptibility in a Northeast population from Brazil.