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Open Access Research article

Subtype specific genetic associations for juvenile idiopathic arthritis: ERAP1 with the enthesitis related arthritis subtype and IL23R with juvenile psoriatic arthritis

Anne Hinks1*, Paul Martin1, Edward Flynn1, Steve Eyre1, Jon Packham2, Childhood Arthritis Prospective Study (CAPS), BSPAR study group, Anne Barton1, Jane Worthington1 and Wendy Thomson1

Author Affiliations

1 Arthritis Research UK Epidemiology Unit, Manchester Academic Health Science Centre, Stopford Building, Oxford Road, The University of Manchester, Manchester, M13 9PT, UK

2 Haywood Hospital, University Hospital of North Staffordshire, High Lane, Stoke on Trent, Staffordshire, ST4 7LN, UK

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Arthritis Research & Therapy 2011, 13:R12  doi:10.1186/ar3235

Published: 31 January 2011

Abstract

Introduction

Juvenile idiopathic arthritis (JIA) is an umbrella term for all chronic childhood arthropathies and can be divided into seven subtypes. It includes the enthesitis related arthritis (ERA) subtype which displays symptoms similar to ankylosing spondylitis (AS) and juvenile-onset psoriatic arthritis which has similarities to psoriatic arthritis (PsA) and psoriasis (Ps). We, therefore, hypothesized that two well-established susceptibility loci for AS and Ps, ERAP1 and IL23R, could also confer susceptibility to these JIA subtypes.

Methods

Single nucleotide polymorphisms (SNPs) in ERAP1 (rs30187) and IL23R (rs11209026) were genotyped in JIA cases (n = 1,054) and healthy controls (n = 5,200). Genotype frequencies were compared between all JIA cases and controls using the Cochrane-Armitage trend test implemented in PLINK. Stratified analysis by ILAR subtype was performed.

Results

The ERA subtype showed strong association with ERAP1 SNP (P trend = 0.005). The IL23R SNP showed significant association in the PsA subtype (P trend = 0.04). The SNPs were not associated with JIA overall or with any other subtype.

Conclusions

We present evidence for subtype specific association of the ERAP1 gene with ERA JIA and the IL23R gene with juvenile-onset PsA. The findings will require validation in independent JIA datasets. These results suggest distinct pathogenic pathways in these subtypes.