Evidence for association of an interleukin 23 receptor variant independent of the R381Q variant with rheumatoid arthritis.

OBJECTIVE: The rare allele of a non-synonymous interleukin 23 receptor (IL23R) single nucleotide polymorphism (SNP) rs11209026 (p.Arg381Gln) confers strong protection against Crohn disease (CD) and psoriasis. Other IL23R variants also exhibit association with CD, genetically independent of rs11209026. In rheumatoid arthritis (RA), IL23 is an important determinant of the production of IL17A, a cytokine of consequence in inflammation and bone destruction. While there is no previous support for strong association of IL23R with RA, the possibility of a weaker role for IL23R variants in the aetiology of RA cannot be eliminated. METHODS: A New Zealand RA cohort was tested for association with six IL23R SNPs and the resulting data combined with a reanalysis of the Wellcome Trust Case Control Consortium data and a previously published Spanish data set. The combined data set totals over 3000 Caucasian cases and 3800 controls, which has sufficient power to detect a risk of as low as odds ratio (OR) = 1.2. RESULTS: Our data emphasise the lack of association of rs11209026 with RA (OR 1.01, 95% confidence interval (CI) 0.88 to 1.16, p = 0.86). However there was some evidence for association of rs1343151 with RA (OR 1.14, 95% CI 1.06 to 1.22, p = <0.001). CONCLUSIONS: While requiring further replication, these data further support a role for the IL17A/IL23 pathway in RA. Understanding how different variants of IL23R associate, at varying levels of strength, with contrasting groups of immune-mediated diseases (CD, psoriasis, ankylosing spondylitis, RA) will enhance knowledge on the aetiology of these diseases.

Genomic DNA pooling for whole-genome association scans in complex disease: empirical demonstration of efficacy in rheumatoid arthritis.

A pragmatic approach that balances the benefit of a whole-genome association (WGA) experiment against the cost of individual genotyping is to use pooled genomic DNA samples. We aimed to determine the feasibility of this approach in a WGA scan in rheumatoid arthritis (RA) using the validated human leucocyte antigen (HLA) and PTPN22 associations as test loci. A total of 203 269 single-nucleotide polymorphisms (SNPs) on the Affymetrix 100K GeneChip and Illumina Infinium microarrays were examined. A new approach to the estimation of allele frequencies from Affymetrix hybridization intensities was developed involving weighting for quality signals from the probe quartets. SNPs were ranked by z-scores, combined from United Kingdom and New Zealand case-control cohorts. Within a 1.7 Mb HLA region, 33 of the 257 SNPs and at PTPN22, 21 of the 45 SNPs, were ranked within the top 100 associated SNPs genome wide. Within PTPN22, individual genotyping of SNP rs1343125 within MAGI3 confirmed association and provided some evidence for association independent of the PTPN22 620W variant (P=0.03). Our results emphasize the feasibility of using genomic DNA pooling for the detection of association with complex disease susceptibility alleles. The results also underscore the importance of the HLA and PTPN22 loci in RA aetiology.

An investigation into the levels of radiation exposure in diagnostic examinations involving fluoroscopy.

In order to investigate the levels of radiation exposure resulting from fluoroscopic examinations, area-exposure product measurements were performed on 6532 patients whilst undergoing a variety of examinations at a large district general hospital. Results for both the same and different types of examinations, performed in two different X-ray rooms by a number of different radiologists, are compared in order to highlight some of the factors which influence the wide variations in patient exposure which frequently occur in radiological examinations. Variations in exposure of patients of different weights are also presented.