Concurrent Oral 6 - Spondylarthropathies [OP40-OP47]: OP40. Association of IL23R and IL12B Polymorphisms with Psoriatic Arthritis

Background: Between 7–42% of psoriasis patients are affected by psoriatic arthritis (PsA). Genetic studies have demonstrated associations between interleukin-23 receptor (IL-23R) and interleukin-12-beta (IL-12B) gene variations with susceptibility to PsA and psoriasis. The aim of this study was to investigate previously reported single-nucleotide polymorphisms (SNPs) in genes coding for IL-23R and IL-12B, to ascertain if they related to more specific clinical phenotypes within PsA. Methods: 267 patients (134 males, median age 35 years, IQR 27–49) attending the RNHRD, in Bath, with a diagnosis of PsA were compared with 4941 (5422 for rs6887695) controls (Wellcome Trust Case Control Consortium) for IL-23R and IL-12B. The two groups were genotyped for SNPs in the IL-23R region of chromosome 1 (rs11209026 and rs7530511) and IL-12B region of chromosome 5 (rs6887695). A diagnosis of PsA was made using the Moll and Wright classification and the following clinical phenotypes measured: age at onset of psoriasis / PsA, number of involved joints, radiographic erosions and PASI score (Psoriasis Area Severity Index). Statistical analysis was performed using the Pearson Chi-Square with Yates Continuity Correction test or the Mann-Whitney U Test for non-parametric data. The data was analysed using SPSS-14. Results: Genotype frequencies in both groups were in Hardy-Weinberg equilibrium. There was a strong association between the IL-12B SNP (rs6887595) and PsA, with homozygosity for the common allele being more frequent in PsA than in controls [see Table, odds ratio 1.7 (1.3 - 2.2), P < 0.001]. There was no association with any particular clinical phenotype. Previously reported associations between IL-23R SNPs and PsA were not confirmed, although homozygosity for the minor allele of rs11209026 was absent in PsA and there was a trend for the minor allele to be less frequent in patients with erosive joint disease than in those without erosion or in controls (6.9%, 13.3% and 12.8%, respectively). Conclusions: There is a strong association between the rs6887595 SNP of IL-12B and Psoriatic disease. A possible association between IL-23R and erosive joint disease may emerge with larger studies. Comparison of IL-23R and IL-12B genotype frequencies Comparison of IL-23R and IL-12B genotype frequencies Disclosure statement: All authors have declared no conflicts of interest.