IL-13/IL-4/IL-4R system has strong chondroprotective activity. We investigated polymorphisms in these genes as potential hand osteoarthritis (OA) susceptibility loci by performing a case-control association study.
Eighteen common single nucleotide polymorphisms (SNPs) (nine in IL-4R, five in IL-4 and four in IL-13) were genotyped in 403 patients (380 females) with hand OA and 322 healthy controls (308 females).
Two SNPs (rs1805013 and rs1805015), mapping to the IL-4R gene, were associated with P-values of 0.0116 and 0.0305 respectively in the whole sample. As far as the non-erosive hand OA group (n=159) is concerned, the significance level of association of SNP rs1805013 is increased. After correction for multiple testing (correction for the 54 tests) the significance was not retained. None of the IL-13 SNPs analyzed showed association with hand OA. Some of the analyzed SNP within the IL-4 gene showed significant association with hand OA only when considering subgroups of patients. With respect to the CMC1 OA group, two SNPs in IL-4 (rs2243250 and rs2243274) showed association with a P-value of 0.027 and 0.018 respectively. None of these associations remained after correction for multiple testing.
The present study shows a trend to an association between non-erosive hand OA in Caucasian population and a genetic variant in the coding region of IL-4R gene. Our results, in keeping with previous data on hip OA, confirm the suggestion that IL-4/IL-4R system plays a role in OA pathogenesis. Further confirmation studies on different populations are necessary.