Genome-Wide Association Meta-Analysis Reveals Novel Juvenile Idiopathic Arthritis Susceptibility Loci

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic disease and has a strong genomic component. To date, JIA genetic association studies have had limited sample sizes, used heterogeneous patient populations, or included only candidate regions. The aim of this study was to identify new associations between JIA patients with oligoarticular disease and those with IgM rheumatoid factor (RF)-negative polyarticular disease, which are clinically similar and the most prevalent JIA disease subtypes.

METHODS

Three cohorts comprising 2,751 patients with oligoarticular or RF-negative polyarticular JIA were genotyped using the Affymetrix Genome-Wide SNP Array 6.0 or the Illumina HumanCoreExome-12+ Array. Overall, 15,886 local and out-of-study controls, typed on these platforms or the Illumina HumanOmni2.5, were used for association analyses. High-quality single-nucleotide polymorphisms (SNPs) were used for imputation to 1000 Genomes prior to SNP association analysis.

RESULTS

Meta-analysis showed evidence of association (P < 1 × 10^-6 ) at 9 regions: PRR9_LOR (P = 5.12 × 10^-8 ), ILDR1_CD86 (P = 6.73 × 10^-8 ), WDFY4 (P = 1.79 × 10^-7 ), PTH1R (P = 1.87 × 10^-7 ), RNF215 (P = 3.09 × 10^-7 ), AHI1_LINC00271 (P = 3.48 × 10^-7 ), JAK1 (P = 4.18 × 10^-7 ), LINC00951 (P = 5.80 × 10^-7 ), and HBP1 (P = 7.29 × 10^-7 ). Of these, PRR9_LOR, ILDR1_CD86, RNF215, LINC00951, and HBP1 were shown, for the first time, to be autoimmune disease susceptibility loci. Furthermore, associated SNPs included cis expression quantitative trait loci for WDFY4, CCDC12, MTP18, SF3A1, AHI1, COG5, HBP1, and GPR22.

CONCLUSION

This study provides evidence of both unique JIA risk loci and risk loci overlapping between JIA and other autoimmune diseases. These newly associated SNPs are shown to influence gene expression, and their bounding regions tie into molecular pathways of immunologic relevance. Thus, they likely represent regions that contribute to the pathology of oligoarticular JIA and RF-negative polyarticular JIA.

The risk of failure after primary orchidopexy: an 18 year review

OBJECTIVE

To review the primary orchidopexy failure rate and outcome of repeat orchidopexy in a tertiary paediatric surgical centre and identify risk factors.

METHODS

A prospectively collected and validated audits system was used to identify all boys having a repeat orchidopexy from August 1990 to December 2008 (18 years).

RESULTS

In total, 1538 boys underwent orchidopexy with 1886 testicles operated on. Of these 348 (22.6%) patients had bilateral cryptorchidism. A need for repeat orchidopexy was identified in 31 boys resulting in a primary failure rate of 1.6% over the 18 years. Unilateral orchidopexy as the primary operation had a 1.5% failure rate. The failure rate for bilateral cryptorchidism was 1.87% per testicle rising to 1.93% per testicle when the primary operation was synchronous bilateral orchidopexy. Orchidopexy failure occurred in 9 patients (1.97%) who were under 24 months, 15 (2.67%) who were between 24 and 72 months and 7 (0.8%) over 72 months at time of first operation.

CONCLUSION

Possible risk factors for primary orchidopexy failure are bilateral operation and older age at time of operation. Failure in achieving a satisfactory scrotal position (and testicular loss) following orchidopexy has been postulated as a potential surgical standard for revalidation of paediatric surgeons. This study adds important contemporary data to inform that process.