Dataset Information

Exome Sequencing and Genotyping Identify a Rare Variant in NLRP7 Gene Associated With Ulcerative Colitis.

ABSTRACT: Background and Aims:Although genome-wide association studies [GWAS] in inflammatory bowel disease [IBD] have identified a large number of common disease susceptibility alleles for both Crohn's disease [CD] and ulcerative colitis [UC], a substantial fraction of IBD heritability remains unexplained, suggesting that rare coding genetic variants may also have a role in pathogenesis. We used high-throughput sequencing in families with multiple cases of IBD, followed by genotyping of cases and controls, to investigate whether rare protein-altering genetic variants are associated with susceptibility to IBD. Methods:Whole-exome sequencing was carried out in 10 families in whom three or more individuals were affected with IBD. A stepwise filtering approach was applied to exome variants, to identify potential causal variants. Follow-up genotyping was performed in 6025 IBD cases [2948 CD; 3077 UC] and 7238 controls. Results:Our exome variant analysis revealed coding variants in the NLRP7 gene that were present in affected individuals in two distinct families. Genotyping of the two variants, p.S361L and p.R801H, in IBD cases and controls showed that the p.S361L variant was significantly associated with an increased risk of ulcerative colitis [odds ratio 4.79, p = 0.0039] and IBD [odds ratio 3.17, p = 0.037]. A combined analysis of both variants showed suggestive association with an increased risk of IBD [odds ratio 2.77, p = 0.018]. Conclusions:The results suggest that NLRP7 signalling and inflammasome formation may be a significant component in the pathogenesis of IBD.

SUBMITTER: Onoufriadis A

PROVIDER: S-EPMC6290881 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Exome Sequencing and Genotyping Identify a Rare Variant in NLRP7 Gene Associated With Ulcerative Colitis.

Onoufriadis Alexandros A Stone Kristina K Katsiamides Antreas A Amar Ariella A Omar Yasmin Y de Lange Katrina M KM Taylor Kirstin K Barrett Jeffrey C JC Pollok Richard R Hayee Bu'Hussain B Mansfield John C JC Sanderson Jeremy D JD Simpson Michael A MA Mathew Christopher G CG Prescott Natalie J NJ

Journal of Crohn's & colitis 20180201 3

<h4>Background and aims</h4>Although genome-wide association studies [GWAS] in inflammatory bowel disease [IBD] have identified a large number of common disease susceptibility alleles for both Crohn's disease [CD] and ulcerative colitis [UC], a substantial fraction of IBD heritability remains unexplained, suggesting that rare coding genetic variants may also have a role in pathogenesis. We used high-throughput sequencing in families with multiple cases of IBD, followed by genotyping of cases and ...[more]

PMID: 29211899

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Project description:Background:Extraordinary progress has been made in our understanding of common variants in many diseases, including melanoma. Because the contribution of rare coding variants is not as well characterized, we performed an exome-wide, gene-based association study of familial cutaneous melanoma (CM) and ocular melanoma (OM). Methods:Using 11?990 jointly processed individual DNA samples, whole-exome sequencing was performed, followed by large-scale joint variant calling using GATK (Genome Analysis ToolKit). PLINK/SEQ was used for statistical analysis of genetic variation. Four models were used to estimate the association among different types of variants. In vitro functional validation was performed using three human melanoma cell lines in 2D and 3D proliferation assays. In vivo tumor growth was assessed using xenografts of human melanoma A375 melanoma cells in nude mice (eight mice per group). All statistical tests were two-sided. Results:Strong signals were detected for CDKN2A (Pmin = 6.16?×?10-8) in the CM cohort (n?=?273) and BAP1 (Pmin = 3.83?×?10-6) in the OM (n?=?99) cohort. Eleven genes that exhibited borderline association (P < 10-4) were independently validated using The Cancer Genome Atlas melanoma cohort (379?CM, 47 OM) and a matched set of 3563 European controls with CDKN2A (P = .009), BAP1 (P = .03), and EBF3 (P = 4.75?×?10-4), a candidate risk locus, all showing evidence of replication. EBF3 was then evaluated using germline data from a set of 132 familial melanoma cases and 4769 controls of UK origin (joint P = 1.37?×?10-5). Somatically, loss of EBF3 expression correlated with progression, poorer outcome, and high MITF tumors. Functionally, induction of EBF3 in melanoma cells reduced cell growth in vitro, retarded tumor formation in vivo, and reduced MITF levels. Conclusions:The results of this large rare variant germline association study further define the mutational landscape of hereditary melanoma and implicate EBF3 as a possible CM predisposition gene.

Project description:BACKGROUND: Genome-wide association studies have revealed that rare variants are responsible for a large portion of the heritability of some complex human diseases. This highlights the increasing importance of detecting and screening for rare variants. Although the massively parallel sequencing technologies have greatly reduced the cost of DNA sequencing, the identification of rare variant carriers by large-scale re-sequencing remains prohibitively expensive because of the huge challenge of constructing libraries for thousands of samples. Recently, several studies have reported that techniques from group testing theory and compressed sensing could help identify rare variant carriers in large-scale samples with few pooled sequencing experiments and a dramatically reduced cost. RESULTS: Based on quantitative group testing, we propose an efficient overlapping pool sequencing strategy that allows the efficient recovery of variant carriers in numerous individuals with much lower costs than conventional methods. We used random k-set pool designs to mix samples, and optimized the design parameters according to an indicative probability. Based on a mathematical model of sequencing depth distribution, an optimal threshold was selected to declare a pool positive or negative. Then, using the quantitative information contained in the sequencing results, we designed a heuristic Bayesian probability decoding algorithm to identify variant carriers. Finally, we conducted in silico experiments to find variant carriers among 200 simulated Escherichia coli strains. With the simulated pools and publicly available Illumina sequencing data, our method correctly identified the variant carriers for 91.5-97.9% variants with the variant frequency ranging from 0.5 to 1.5%. CONCLUSIONS: Using the number of reads, variant carriers could be identified precisely even though samples were randomly selected and pooled. Our method performed better than the published DNA Sudoku design and compressed sequencing, especially in reducing the required data throughput and cost.

Dataset Information

Exome Sequencing and Genotyping Identify a Rare Variant in NLRP7 Gene Associated With Ulcerative Colitis.

Publications

Exome Sequencing and Genotyping Identify a Rare Variant in NLRP7 Gene Associated With Ulcerative Colitis.

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