The G allele of IL1B (-511G/A) polymorphism was associated with higher peripheral joint disease activity (OR 3.13; p < 0.0004; CI 95 % 1.43-6.82, p (corrected) <0.008), while the G allele of the IL6 (174G > C) polymorphism presented a strong trend to be associated with peripheral forms (70.86 %) (OR 1.89; p < 0.03; CI 95 % 1.06-3.39, p-corrected 0.05).