Association study of il-1ra gene (intron 2 -86 bp) vntr polymorphism with rheumatoid arthritis in vindhyan population

Rheumatoid arthritis (RA) is a chronic, systemicdisease of unknown etiology. Several studies have reported avariable 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 350patients 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).
Polymorphism of the IL-1Ra gene, displays different copies of 86-bp tandem repeat in intron 2. The number of times this sequence is referred to as the copy number of the 86-bp sequence which in turn corresponds to different alleles of this IL-1Ra polymorphism. Five alleles of IL-1RA 86-bp VNTR polymorphism are as follows were classified on basis of number of repeats of 86 bp sequence and PCR product size on gel and designated as A1 (410 bp, 4 repeats), A2 (240 bp, 2 repeats), A3 (500 bp, 5 repeats), A4 (325 bp, 3 repeats) and A5 (595 bp, 6 repeats).Genotype frequencies, allele frequencies and carriage rates of IL-1Ra VNTR alleles are depicted in table no. 4.6. Genotype frequency between rheumatoid arthritis patient and healthy control groups were slightly different and significantly associated with arthritis (χ2=15.25 P=0.0184*). Thus allele frequency (χ2=15.44 P=0.0015**) and carriage rate (χ2=12.60, P=0.0056**) were also significantly different between both case and control groups.