OBJECTIVE: To determine whether systemic juvenile idiopathic arthritis (sJIA) susceptibility loci identified by candidate gene studies demonstrated association with sJIA in the largest study population assembled to date. METHODS: Single nucleotide polymorphisms (SNPs) from 11 previously reported sJIA risk loci were examined for association in 9 populations, including 770 sJIA cases and 6947 control subjects. The effect of sJIA-associated SNPs on gene expression was evaluated in silico in paired whole genome and RNA sequencing data from lymphoblastoid cell lines (LCL) of 373 European 1000 Genomes Project subjects. The relationship between sJIA-associated SNPs and response to anakinra treatment was evaluated in 38 US patients for whom treatment response data were available. RESULTS: We found no association of the 26 SNPs previously reported as sJIA-associated. Expanded analysis of the regions containing the 26 SNPs revealed only one significant association, the promoter region of IL1RN (p<1E-4). sJIA-associated SNPs correlated with IL1RN expression in LCLs, with an inverse correlation between sJIA risk and IL1RN expression. The presence of homozygous IL1RN high expression alleles correlated strongly with non-response to anakinra therapy (OR 28.7 [3.2, 255.8]). CONCLUSION: IL1RN was the only candidate locus associated with sJIA in our study. The implicated SNPs are among the strongest known determinants of IL1RN and IL1RA levels, linking low expression with increased sJIA risk. Homozygous high expression alleles predicted non-response to anakinra therapy, nominating them as candidate biomarkers to guide sJIA treatment. This is an important first step towards the personalized treatment of sJIA. This article is protected by copyright. All rights reserved.
Background In previous studies of PBMC gene expression in s-JIA we noted a strong erythropoiesis signature in patients with severe anaemia, correlating with an expansion of CD34+ progenitor cells [1]. Therefore, the origin of anaemia in sJIA may be different from anaemia of chronic inflammation. We examined CD34+ progenitor cells and PBMC gene expression in patients with s-JIA and other types of JIA.
To investigate if the persistence of systemic features is longer in Hispanic children with systemic juvenile idiopathic arthritis (S-JIA) than in non-Hispanic children with S-JIA and to determine early predictors of systemic and articular disease.We performed a multi-center retrospective chart review of patients followed in six pediatric rheumatology centers with onset of S-JIA from 1974 to 2004. Patients were included in the study if they had been followed for > or = 1 year after disease onset. Information collected included demographic, clinical, laboratory and treatment data. Systemic features included fever, rash, lymphadenopathy, hepatosplenomegaly, pericarditis, and pleuritis.Of the 159 S-JIA patients screened, 120 (75%) met our inclusion criteria. There were 65 boys and 55 girls. The mean follow-up period for Hispanic patients was 5.7 years (SD 4.0) and for non-Hispanic patients was 8.6 years (SD 7.2). There was no significant difference in the presence of systemic features between Hispanic and non-Hispanic patients at 0.5, 1, 2, 4, 6, 8, and 10 years of follow-up. Polyarthritis at the 6-month visit was predictive of systemic features (OR 9.7, 95% CI 1.16-81.35, p = 0.036) and polyarthritis (OR 5.6, 95% CI 1.42-21.8, p = 0.014) at last follow-up.In children with S-JIA, Hispanics did not demonstrate longer persistence of systemic features than non-Hispanics. Polyarthritis at 6 months strongly predicted the development of persistent systemic features and chronic polyarticular disease.
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