Association of 86 bp variable number of tandem repeat (VNTR) polymorphism of interleukin-1 receptor antagonist (IL1RN) with susceptibility and clinical activity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic disease of unknown etiology. Several studies have reported a variable number of tandem repeat (VNTR) 86 bp (rs2234663) in the intron 2 of IL1RN gene with RA risk. The present study was designed to determine the frequencies of this polymorphism in patients with RA and control subjects (CS) and its association with RA in a western Mexican population. An analytical cross-sectional study was performed, in which 350 patients with RA and 307 CS were included. The identification of IL1RN VNTR polymorphism was carried out by polymerase chain reaction (PCR), and genotypes were associated with clinical variables (DAS28 and CRP). The presence of A1/A2 genotype was associated with RA risk (p = 0.03, OR = 1.45, 95% CI = 1.02–2.05). Also, results indicate that the presence of heterozygote genotypes which include A2 was associated with RA risk (p = 0.01, OR = 1.5, 95% CI = 1.07–2.11). Patients carrier of A2/A2 genotype have a higher score of DAS28 (5.64 [4.49–6.70]). A-/A- has higher level of CRP (2.30 [0.62–9.10]) in comparison with A2/A- (1.06 [0.37–2.82]). A1/A2 genotype was associated with susceptibility to RA in a western Mexican population. The presence of the A2/A2 genotype in RA is associated with increased disease activity.