Sean Hamilton

CARD15: a Pleiotropic Autoimmune Gene That Confers Susceptibility to Psoriatic Arthritis

A recent genomewide scan in psoriatic arthritis (PsA) revealed a susceptibility locus at 16q. This region overlaps CARD15, a susceptibility gene in Crohn disease. The possibility of a common susceptibility gene between PsA and Crohn disease is further supported by epidemiological studies that note an increased incidence of psoriasis in subjects with Crohn. We screened 187 patients with PsA and 136 healthy controls, all from Newfoundland, for the three common, independent sequence variants of CARD15 (R702W, leu1007fsinsC, and G908R), which were detected by polymerase chain reaction by use of allele-specific primers and visualized through gel electrophoresis. In total, 53/187 (28.3%) probands with PsA had at least one variant of the CARD15 gene, compared with 16/136 (11.8%) controls (odds ratio 2.97; 95% confidence interval 1.61-5.47; P=.0005). Allele frequencies of R702W, leu1007fsinsC, and G908R were 10.43%, 3.21%, and 1.61%, respectively, in patients with PsA, compared with 3.31%, 2.57%, and 0.37%, respectively, in the control patients. CARD15 conferred susceptibility to PsA independent of HLA-Cw*0602. Thus, CARD15 represents a pleiotropic autoimmune gene and is the first non-MHC gene to be associated with PsA.

Association of functional variants of PTPN22 and tp53 in psoriatic arthritis: a case-control study

Recent studies have implicated PTPN22 and tp53 in susceptibility to several autoimmune diseases, including rheumatoid arthritis, suggesting that these genes are important in maintaining immune homeostasis. Because autoimmune diseases may share similar susceptibility loci, investigation of these genes in psoriatic arthritis (PsA) is of potential relevance. As a result we investigated known coding polymorphisms in PTPN22 and tp53 in a homogenous Caucasian PsA cohort from Newfoundland, Canada and an admixed Caucasian PsA cohort from Toronto, Canada. We observed a moderate association of the R620W variant of PTPN22 with PsA in the Toronto population only. Because of the conflicting findings reported regarding the association of PTPN22 with PsA, further studies in other PsA populations are warranted.

Drug-induced lupus erythematosus presenting with cardiac tamponade: a case report and literature review.

The presentation of drug-induced lupus erythematosus (DILE) is typically mild, with a significantly lower incidence of life-threatening end-organ dysfunction relative to idiopathic systemic lupus erythematosus. DILE is an uncommon cause of cardiac tamponade but has been reported in patients treated with procainamide, isoniazid, hydralazine, sulfasalazine, and carbamazepine. We present a case of DILE presenting with cardiac tamponade associated with infliximab use that resolved with discontinuation of the medication and administration of high-dose steroids. In conclusion, DILE should be considered in the differential diagnosis in cases of pericarditis with cardiac tamponade without a clear cause.

UGT2B17 copy number gain in a large ankylosing spondylitis multiplex family

BackgroundThe primary objective of this study is to identify novel copy number variations (CNVs) associated with familial ankylosing spondylitis (AS). A customized genome-wide microarray was designed to detect CNVs and applied to a multiplex AS family with six (6) affected family members. CNVs were detected using the built-in DNA analytics aberration detection method-2 (ADM-2) algorithm. Gene enrichment analysis was performed to observe the segregation. Subsequent validation was performed using real time quantitative fluorescence polymerase reaction (QF-PCR). The frequency of copy number variation for the UGT2B17 gene was then performed on two well-defined AS cohorts. Fisher exact test was performed to quantify the association.ResultsOur family-based analysis revealed ten gene-enriched CNVs that segregate with all six family members affected with AS. Based on the proposed function and the polymorphic nature of the UGT2B17 gene, the UGT2B17 gene CNV was selected for validation using real time QF-PCR with full concordance. The frequency of two copies of the UGT2B17 gene CNV was 0.41 in the Newfoundland AS cases and 0.35 in the Newfoundland controls (OR = 1.26(0.99-1.59); p < 0.05)), whereas the frequency of two (2) copies of the UGT2B17 gene CNV was 0.40 in the Alberta AS cases and 0.39 in the Alberta controls (OR = 1.05(95% CI: 0.83-1.33); p < 0.71)).ConclusionsA genome-wide microarray interrogation of a large multiplex AS family revealed segregation of the UGT2B17 gene CNV among all affected family members. The association of the UGT2B17 CNV with AS is particularly interesting given the recent association of this CNV with osteoporosis and the proposed function as it encodes a key enzyme that inhibits androgens. However, two copies of the UGT2B17 gene CNV were only marginally significant in a uniplex AS cohort from Newfoundland but not in a uniplex AS cohort from Alberta.

Feasibility of Measurement and Adherence to System Performance Measures for Rheumatoid Arthritis in 5 Models of Care

Objective. To test the feasibility of reporting on 4 national performance measures for patients with rheumatoid arthritis (RA) in 5 different models of care. Methods. The following performance measures were evaluated in 5 models of care: waiting time (WT) to rheumatologist consultation, percentage of patients seen in yearly followup (FU), percentage taking disease-modifying antirheumatic drugs (DMARD), and time to starting DMARD. All models aimed to improve early access and care for patients with RA. Results. A number of feasibility issues were encountered in performance measure evaluation because of differences in site data collection and/or the duration of the model of care. For example, while 4/5 programs maintained clinical or research databases, chart reviews were still required to report on WT. Median WT for care in 2015 varied by site between 21 and 75 days. Yearly FU rates could only be calculated in 2 sites (combined owing to small numbers) and varied between 83% and 100%. Percentage of patients taking a DMARD and time to DMARD could be calculated in 3 models, and rates of DMARD use were between 90% and 100%, with median time to DMARD of 0 days in each. Conclusion. Our review has shown that even in models of care designed to improve access to care and early treatment, data to document improvements are often lacking. Where data were available for measuring, deficits in WT performance were noted for some centers. Our results highlight a need to improve reporting processes to drive quality improvement.

OP0206 Interactions Between Smoking and Methylation Status is Highly Predictive of Radiographic Progression in Ankylosing Spondylitis

Background The variability in the rate of radiographic progression in ankylosing spondylitis (AS) and the role of smoking, as an independent risk factor for radiographic progression, has been well documented. We have recently identified multiple epigenetic variants associated with ankylosis in AS using a genome-wide epigenetic approach. In this study, we examined the recently identified epigenetic markers in an independent AS cohort to assess radiographic progression and determine if an interaction exists with smoking status. Methods Our replication cohort consisted of 76 AS patients (16 females; 32 smokers; 56 HLA-B27+) that had serial radiographs on average 3 years apart (range 1.2 to 7.5 yrs). Of the 76 patients, 35 patients exhibited radiographic progression (change in mSASSS score >0). The mean radiographic progression for the entire group was 0.99 mSASSS/yr. The DNA methylation experiments on 17 CpG sites were designed using EpiTyper and performed on a Sequenom MassArray 4 system. The association between methylation score and radiographic progression rate was examined by multiple linear regressions after controlling for age of onset and gender. An interaction between methylation score and smoking status was introduced into the model to examine the association in the smokers and non-smokers, respectively. The Akaike information criterion (AIC) was used to assess the goodness of fit. Methylation sites with more than 15% of data missing were excluded from the analysis. The total methylation score of 7 CpG sites had the best goodness of fit. Results In the univariate analysis, high total methylation score was significantly associated with less radiographic progression (β=-0.97; 95%CI=-1.91:-0.02; p=0.04). Smokers demonstrated worse radiographic progression than non-smokers, but it was not statistically significant (p=0.62). In the multivariate analysis, the interaction between methylation score and smoke status was statistically significant (p=0.008). Among smokers, high total methylation score was significantly associated with less radiographic progression (β=-2.01; 95%CI=-3.26:-0.75; p=0.0017). No such association was observed among non-smokers. Conclusions This is the first study to demonstrate how epigenetic factors can influence radiographic progression in AS. Specifically, the results from this study reveal a significant association between smoking, methylation status and radiographic progression in AS. Disclosure of Interest None declared

OP0200 Global DNA Methylation Patterns Differ Between Responders and Non-Responders in Psoriatic Arthritis Patients Treated with Tumor Necrosis Factor-α Inhibitors

Background Although tumor necrosis factor-α inhibitors TNFi are well established treatment for psoriatic arthritis (PsA), the efficacy can vary greatly between patients. In this study, we examined the genome-wide epigenetic changes among TNFi responders and TNFi secondary failures in PsA patients Methods Twenty-one PsA patients (15 males; 6 females) were considered TNFi responders of which 13 were treated with etanercept and 8 with adalumimab. The median follow up duration was 18 months. Twenty patients (5 males; 15 females) were secondary TNFi failures of which 15 were treated with etanercept and 5 with adalumimab. The median follow up duration was 36 months. Genome-wide DNA methylation profiling was performed using the Illumina HumanMethylation450k Beadchip, which measures ∼480,000 different CpG sites per sample and covers 96% of RefSeq genes. The methylation level at each CpG site was measured by β values varying from 0 (no methylation) to 1 (100% methylation). Analysis was performed using a t-test after a Bonferroni-Holm correction was applied. Regions of interest were selected based on β value (β diff>5%) and p-value (p<0.01). Results After quality control filtering, 384,599 and 368,863 CpG sites were evaluated for TNFi responders and TNFi failures, respectively. Analysis revealed 72 and 91 CpG sites of interest in the TNFi responder group and in the TNFi failure group, respectively. Top gene candidates for TNFi responders included TRAPPC9 (β diff=0.056; p=3.42x10-6 - functions as an activator of NFkB); CCR6 (β diff=0.053; p=0.0028 - regulates the migration and recruitment of dentritic and T cells); and PSORSC13 (β diff=0.035; p=0.003). Top candidate genes for TNFi secondary failures included CD70 (encoded protein is a ligand for TNFRSF27/CD27), and TNFRSF1B (a member of the TNF receptor superfamily, that mediates most of the metabolic effects of TNFα). Conclusions These preliminary results demonstrate that the global DNA methylation pattern differs between TNFi responders and secondary failures. They also serve to highlight the possible importance of epigenetic (methylation) changes with respect to the TNFα signaling pathway. High priority candidate regions and genes identified in this study warrant further validation. Disclosure of Interest None declared

OP0095 Customized CNV microarray identified UGT2B17 as a novel susceptibility gene associated with familial ankylosing spondylitis

Background Ankylosing spondylitis (AS) exhibits a strong genetic predisposition which is only partially accounted for with SNP-based genome-wide associations. To date no structural variations such as copy number variations (CNVs) have been reported to be associated with AS. Objectives To identify highly penetrant, novel CNVs associated with familial AS by employing a custom genome-wide microarray. Methods Our custom microarray which was comprised of 2 X 1 million probes targeting the rearrangement hotspots (mean spacing of 280 bp) was applied on a large multiplex three generational Caucasian AS family of North European ancestry. This multiplex family was consisted of five (5) individuals affected with AS, two (2) members with Systemic lupus erythematosus (SLE) and three (3) unaffected individuals. An ethnically-matched control was used for hybridization. A minimum of five (5) probes were required to call an aberration with an average intensity >0.25 and <-0.25 for a duplication and deletion, respectively. Independent validation was performed for CNV’s identified by the custom microarray using taqman-based quantitative polymerase chain reaction (qPCR). Results Microarray analysis revealed complex rearrangements within AS patients in multiple regions not present within the unaffected family members. The most compelling evidence for structural variation was excessive genomic gains observed for the UGT2B17 gene. Duplication of the UGT2B17 gene was present in all five (5) patients with AS (i.e., two males and three females) and in a patient with SLE. No genomic gain was detected in unaffected family members. Validation using qPCR demonstrated complete concordance with the microarray results with all five (5) AS individuals contained ≥2 copies of the UGT2B17 gene, whereas unaffected individuals had only a single copy. The population frequency of the UGT2B17 CNV among Caucasians is 0.15 for a deletion, 0.45 for one copy, and 0.25 for two or more copies. The UGT2B17 gene encodes a key enzyme responsible for glucuronidation of androgens which stimulate bone formation. Interestingly, deletion of the UGT2B17 gene has been associated with osteoporosis (Yang TL et al., 2008); however, this association was not replicated in an independent study (Chew S et al., 2011). Conclusions This is the first report of structural variants (i.e., CNVs) being associated with familial AS. Given the proposed function of this gene in stimulating bone formation, it should be considered a high priority susceptibility gene in familial AS. Replication studies and further functional studies are warranted. Disclosure of Interest None Declared