PLoS ONE (Jan 2012)

Association of the IL-10 gene family locus on chromosome 1 with juvenile idiopathic arthritis (JIA).

  • Ebun Omoyinmi,
  • Paola Forabosco,
  • Raja Hamaoui,
  • Annette Bryant,
  • Anne Hinks,
  • Simona Ursu,
  • Childhood Arthritis Prospective Study (CAPS),
  • BSPAR study group,
  • Childhood Arthritis Response to Medication Study (CHARMS),
  • Lucy R Wedderburn,
  • Wendy Thomson,
  • Cathryn M Lewis,
  • Patricia Woo

DOI
https://doi.org/10.1371/journal.pone.0047673
Journal volume & issue
Vol. 7, no. 10
p. e47673

Abstract

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BackgroundThe cytokine IL-10 and its family members have been implicated in autoimmune diseases and we have previously reported that genetic variants in IL-10 were associated with a rare group of diseases called juvenile idiopathic arthritis (JIA). The aim of this study was to fine map genetic variants within the IL-10 cytokine family cluster on chromosome 1 using linkage disequilibrium (LD)-tagging single nucleotide polymorphisms (tSNPs) approach with imputation and conditional analysis to test for disease associations.Methodology/principal findingsFifty-three tSNPs were tested for association between Caucasian paediatric cohorts [219 systemic JIA (sJIA), 187 persistent oligoarticular JIA (pOJIA), and 139 extended OJIA (eOJIA) patients], and controls (Wellcome Trust control cohort, WTCCC2). Significant association with sJIA was detected at rs1400986 in the promoter of IL-20 (odds ratio 1.53; 95% CI 1.21-1.93; p = 0.0004), but in no other subtypes. Imputation analysis identified additional associated SNPs for pOJIA at IL-20 and IL-24, including a rare, functional, missense variant at IL-24 with a p = 0.0002. Penalised logistic regression analysis with HyperLasso and conditional analysis identified several further associations with JIA subtypes. In particular, haplotype analysis refined the sJIA association, with a joint effect at rs1400986 and rs4129024 in intron 1 of MAPKAPK2 (p = 3.2E-5). For pOJIA, a 3-SNP haplotype including rs1878672 in intron 3 of IL-10 showed evidence for association (p = 0.0018). In eOJIA, rs10863962 (3'UTR of FCAMR) and rs12409577 (intron of IL-19) haplotype showed some evidence of association (p = 0.0003).ConclusionsThis study supports previous association of IL-20 with sJIA. Haplotype analyses provided stronger association signals than single point analyses, while a penalised logistic regression approach also suggested multiple independent association signals. Replication studies are required to confirm or refute these findings. The results indicate that combined effects with unknown/rare variants remain to be characterised in JIA, and represent a possible example of synthetic association in this region.