A protein-truncating R179X variant in RNF186 confers protection against ulcerative colitis

Protein-truncating variants protective against human disease provide in vivo validation of therapeutic targets. Here we used targeted sequencing to conduct a search for protein-truncating variants conferring protection against inflammatory bowel disease exploiting knowledge of common variants associated with the same disease. Through replication genotyping and imputation we found that a predicted protein-truncating variant (rs36095412, p.R179X, genotyped in 11,148 ulcerative colitis patients and 295,446 controls, MAF = up to 0.78%) in RNF186, a single-exon ring finger E3 ligase with strong colonic expression, protects against ulcerative colitis (overall P = 6.89 x 10(-7), odds ratio = 0.30). We further demonstrate that the truncated protein exhibits reduced expression and altered subcellular localization, suggesting the protective mechanism may reside in the loss of an interaction or function via mislocalization and/or loss of an essential transmembrane domain.Peer reviewe

Deep Resequencing of GWAS Loci Identifies Rare Variants in <i>CARD9</i>, <i>IL23R</i> and <i>RNF186</i> That Are Associated with Ulcerative Colitis

Genome-wide association studies and follow-up meta-analyses in Crohn's disease (CD) and ulcerative colitis (UC) have recently identified 163 disease-associated loci that meet genome-wide significance for these two inflammatory bowel diseases (IBD). These discoveries have already had a tremendous impact on our understanding of the genetic architecture of these diseases and have directed functional studies that have revealed some of the biological functions that are important to IBD (e.g. autophagy). Nonetheless, these loci can only explain a small proportion of disease variance (~14% in CD and 7.5% in UC), suggesting that not only are additional loci to be found but that the known loci may contain high effect rare risk variants that have gone undetected by GWAS. To test this, we have used a targeted sequencing approach in 200 UC cases and 150 healthy controls (HC), all of French Canadian descent, to study 55 genes in regions associated with UC. We performed follow-up genotyping of 42 rare non-synonymous variants in independent case-control cohorts (totaling 14,435 UC cases and 20,204 HC). Our results confirmed significant association to rare non-synonymous coding variants in both IL23R and CARD9, previously identified from sequencing of CD loci, as well as identified a novel association in RNF186. With the exception of CARD9 (OR = 0.39), the rare non-synonymous variants identified were of moderate effect (OR = 1.49 for RNF186 and OR = 0.79 for IL23R). RNF186 encodes a protein with a RING domain having predicted E3 ubiquitin-protein ligase activity and two transmembrane domains. Importantly, the disease-coding variant is located in the ubiquitin ligase domain. Finally, our results suggest that rare variants in genes identified by genome-wide association in UC are unlikely to contribute significantly to the overall variance for the disease. Rather, these are expected to help focus functional studies of the corresponding disease loci. © 2013 Beaudoin et al

Genetic variation in myosin IXB is associated with ulcerative colitis.

BACKGROUND & AIMS: Common germline genetic variation in the 3' region of myosin IXB (MYO9B) has been associated recently with susceptibility to celiac disease, with a hypothesis that MYO9B variants might influence intestinal permeability. These findings suggested the current study investigating a possible further role for MYO9B variation in inflammatory bowel disease. METHODS: Eight single-nucleotide polymorphisms (SNPs) were selected to tag common haplotypes from the 35-kb 3' region of MYO9B. These included the strongest celiac disease-associated variants reported in a Dutch cohort. These SNPs were studied in 3 independently collected and genotyped case-control cohorts of European descent (UK, Dutch, and Canadian/Italian), comprising in total 2717 inflammatory bowel disease patients (1197 with Crohn's disease, 1520 with ulcerative colitis) and 4440 controls. RESULTS: Common variation in MYO9B was associated with susceptibility to inflammatory bowel disease in all 3 cohorts examined (most associated SNP, rs1545620; meta-analysis P = 1.9 x 10(-6); odds ratio, 1.2), with the same alleles showing association as reported for celiac disease. CONCLUSIONS: MYO9B genetic variants predispose to inflammatory bowel disease. Interestingly, rs1545620 is a nonsynonymous variant leading to an amino acid change (Ala1011Ser) in the third calmodulin binding IQ domain of MYO9B. Unlike previous variants (in other genes) reported to predispose to inflammatory bowel disease, the association at MYO9B was considerably stronger with ulcerative colitis, although weaker association with Crohn's disease also was observed. These data imply shared causal mechanisms underlying intestinal inflammatory diseases

Pill Burden Influences the Association Between Time-Based Prospective Memory and Antiretroviral Therapy Adherence in Younger But Not Older HIV-Infected Adults

Prospective memory (PM) is associated with antiretroviral (ARV) adherence in HIV, but little is known about how pill burden and age might affect this association. One hundred seventeen older (≥50&nbsp;years) and 82 younger (&lt;50&nbsp;years) HIV-infected adults were administered a measure of PM in the laboratory and subsequently were monitored for ARV adherence for 30&nbsp;days using the Medication Event Monitoring System. In the older group, better time-based PM performance was associated with higher likelihood of adherence, irrespective of pill burden. Within the younger sample, time-based PM was positively related to adherence only in participants with lower pill burdens. Younger HIV-infected individuals with higher pill burdens may overcome the normal effects of time-based PM on adherence through compensatory medication-taking strategies, whereas suboptimal use of these strategies by younger HIV-infected individuals with lower pill burdens may heighten their risk of ARV nonadherence secondary to deficits in time-based PM

Health-Related Everyday Functioning in the Internet Age: HIV-Associated Neurocognitive Disorders Disrupt Online Pharmacy and Health Chart Navigation Skills

This study evaluated the effects of HIV-associated Neurocognitive Disorders (HAND) on 2 Internet-based tests of healthcare management. Study participants included 46 individuals with HIV infection, 19 of whom were diagnosed with HAND, and 21 seronegatives. Participants were administered Internet-based tests of online pharmacy and health records navigation skills in which they used mock credentials to log in to an experimenter-controlled website and independently perform a series of typical online health-related behaviors (e.g., refill a prescription, read and interpret an electronic chart note). HAND was associated with significantly lower accuracy on both the online pharmacy and health records navigation tasks. Among the HIV+ participants, poorer performance on the online healthcare navigation tasks was associated with fewer years of education, higher plasma viral load, less frequent Internet use, and lower health literacy. Findings indicate that individuals with HAND may have marked difficulties navigating the Internet to complete important health-related behaviors