RESUMO
Genome-wide association studies (GWAS) have identified common variants of modest-effect size at hundreds of loci for common autoimmune diseases; however, a substantial fraction of heritability remains unexplained, to which rare variants may contribute. To discover rare variants and test them for association with a phenotype, most studies re-sequence a small initial sample size and then genotype the discovered variants in a larger sample set. This approach fails to analyse a large fraction of the rare variants present in the entire sample set. Here we perform simultaneous amplicon-sequencing-based variant discovery and genotyping for coding exons of 25 GWAS risk genes in 41,911 UK residents of white European origin, comprising 24,892 subjects with six autoimmune disease phenotypes and 17,019 controls, and show that rare coding-region variants at known loci have a negligible role in common autoimmune disease susceptibility. These results do not support the rare-variant synthetic genome-wide-association hypothesis (in which unobserved rare causal variants lead to association detected at common tag variants). Many known autoimmune disease risk loci contain multiple, independently associated, common and low-frequency variants, and so genes at these loci are a priori stronger candidates for harbouring rare coding-region variants than other genes. Our data indicate that the missing heritability for common autoimmune diseases may not be attributable to the rare coding-region variant portion of the allelic spectrum, but perhaps, as others have proposed, may be a result of many common-variant loci of weak effect.
Assuntos
Doenças Autoimunes/genética , Predisposição Genética para Doença/genética , Variação Genética/genética , Fases de Leitura Aberta/genética , Éxons/genética , Frequência do Gene , Estudo de Associação Genômica Ampla , Humanos , Modelos Genéticos , Mutação/genética , Fenótipo , Tamanho da Amostra , Reino Unido , População Branca/genéticaRESUMO
The contribution of rare coding sequence variants to genetic susceptibility in complex disorders is an important but unresolved question. Most studies thus far have investigated a limited number of genes from regions which contain common disease associated variants. Here we investigate this in inflammatory bowel disease by sequencing the exons and proximal promoters of 531 genes selected from both genome-wide association studies and pathway analysis in pooled DNA panels from 474 cases of Crohn's disease and 480 controls. 80 variants with evidence of association in the sequencing experiment or with potential functional significance were selected for follow up genotyping in 6,507 IBD cases and 3,064 population controls. The top 5 disease associated variants were genotyped in an extension panel of 3,662 IBD cases and 3,639 controls, and tested for association in a combined analysis of 10,147 IBD cases and 7,008 controls. A rare coding variant p.G454C in the BTNL2 gene within the major histocompatibility complex was significantly associated with increased risk for IBD (p = 9.65x10-10, OR = 2.3[95% CI = 1.75-3.04]), but was independent of the known common associated CD and UC variants at this locus. Rare (<1%) and low frequency (1-5%) variants in 3 additional genes showed suggestive association (p<0.005) with either an increased risk (ARIH2 c.338-6C>T) or decreased risk (IL12B p.V298F, and NICN p.H191R) of IBD. These results provide additional insights into the involvement of the inhibition of T cell activation in the development of both sub-phenotypes of inflammatory bowel disease. We suggest that although rare coding variants may make a modest overall contribution to complex disease susceptibility, they can inform our understanding of the molecular pathways that contribute to pathogenesis.
Assuntos
Colite Ulcerativa/genética , Doença de Crohn/genética , Estudo de Associação Genômica Ampla , Glicoproteínas de Membrana/genética , Butirofilinas , Colite Ulcerativa/imunologia , Colite Ulcerativa/patologia , Doença de Crohn/imunologia , Doença de Crohn/patologia , Estudos de Associação Genética , Predisposição Genética para Doença , Antígenos HLA/genética , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
CARD8 (TUCAN) is implicated in the regulation of apoptosis and inflammation, and is a positional and functional candidate gene for inflammatory bowel disease (IBD). Recent investigations have reported conflicting results of association between a CARD8 nonsynonymous SNP, rs2043211, and IBD. SNP rs2043211 results in an A>T transversion in the CARD8 template strand, which introduces a stop codon polymorphism (Cys10Stop), and genotyping of the Cys10Stop variant revealed that 9% of the control population was homozygous for the 'Stop' allele. The effect of the Stop allele on mRNA and protein expression of the two known isoforms of this gene was investigated. IBD patients homozygous for the Stop allele showed somewhat reduced expression of CARD8 mRNA, but, contrary to expectation, expressed a 48 kDa protein isoform. A search of the EST database and reverse transcription-PCR analysis revealed a novel coding exon and three novel CARD8 mRNA isoforms that are conserved in primates. The isoforms of CARD8 differ in their N-termini, resulting in diverse predicted molecular weights (47, 48, 51, 54 and 60 kDa) and multiple outcomes for the variant including Cys10Stop, Cys34Stop, Phe52Ile and Phe102Ile; one isoform may arise through transcription and translation initiated downstream of rs2043211 to yield a novel protein isoform of approximately 47 kDa. The multiple isoforms and differing consequences for a predicted stop codon polymorphism underline the importance of detailed analysis of the effects of proposed functional variants on gene expression.
Assuntos
Processamento Alternativo/genética , Proteínas Adaptadoras de Sinalização CARD/genética , Códon sem Sentido/genética , Doença de Crohn/genética , Proteínas de Neoplasias/genética , Western Blotting , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Linhagem Celular , Doença de Crohn/metabolismo , Etiquetas de Sequências Expressas , Genótipo , Proteínas de Neoplasias/metabolismo , Isoformas de Proteínas/genética , RNA Mensageiro/genéticaRESUMO
OBJECTIVES: Genetic variants at the CARD15 and IBD5 loci are strongly associated with Crohn's disease (CD), but evidence of the effect of these variants on the clinical expression of CD is conflicting and has often been hampered by small sample sizes. We studied 630 well-characterized patients to clarify the genotype/phenotype relationship in CD. METHODS: Patients and healthy controls were genotyped for three common mutations in CARD15 and a marker of the IBD5 risk haplotype. Allele frequencies were compared between phenotypic subgroups using chi2 or Fisher's exact tests. Genotype/phenotype analysis was carried out using multinomial logistic regression modelling allowing for adjustment for correlated or confounding factors. RESULTS: The mean age at diagnosis was significantly lower in carriers of the CARD15 or IBD5 risk alleles. After correction for age and smoking, CARD15 mutations were strongly associated with both ileal disease (P=8.8 x 10(-6)) and stenotic disease (P=0.003), but the association with stenotic disease appeared to be due to a confounding effect with ileal disease. CARD15 mutations were also associated with the presence of granulomas (P=5.7 x 10(-5)), which remained significant after adjustment for age at diagnosis and disease location (P=0.0047). The IBD5 risk haplotype frequency was significantly elevated in cases with perianal disease (P=0.028) and axial spondyloarthropathy (P=0.012). CONCLUSION: Genetic variants at the CARD15 and IBD5 loci have diverse effects on clinical expression in CD. CARD15 mutations are significantly correlated with the presence of granulomas.
Assuntos
Doença de Crohn/genética , Ileíte/genética , Mutação/genética , Proteína Adaptadora de Sinalização NOD2/genética , Adolescente , Adulto , Idade de Início , Criança , Feminino , Frequência do Gene , Genótipo , Granuloma/genética , Humanos , Desequilíbrio de Ligação/genética , Masculino , Fenótipo , Complicações Pós-Operatórias/etiologia , RecidivaRESUMO
Three common mutations in the CARD15 (NOD2) gene are known to be associated with susceptibility to Crohn disease (CD), and genetic data suggest a gene dosage model with an increased risk of 2-4-fold in heterozygotes and 20-40-fold in homozygotes. However, the discovery of numerous rare variants of CARD15 indicates that some heterozygotes for the common mutations have a rare mutation on the other CARD15 allele, which would support a recessive model for CD. We addressed this issue by screening CARD15 for mutations in 100 CD patients who were heterozygous for one of the three common mutations. We also developed a strategy for evaluating potential disease susceptibility alleles (DSAs) that involves assessing the degree of evolutionary conservation of involved residues, predicted effects on protein structure and function, and genotyping in a large sample of cases and controls. The evolutionary analysis was aided by sequencing the entire coding region of CARD15 in three primates (chimp, gibbon, and tamarin) and aligning the human sequence with these and orthologs from other species. We found that 11 of the 100 CD patients screened had a second potential pathogenic mutation within the exonic and periexonic sequences examined. Assuming that there are no additional pathogenic mutations in noncoding regions, our study suggests that most carriers of the common DSAs are true heterozygotes, and supports previous evidence for a gene dosage model. Four novel nonsynonymous mutations were detected, one of which would produce premature termination of translation c.2686C>T (p.Arg896X). Two potential DSAs--c.2107C>T (p.Arg703Cys) and g.2238T>A (c.74-7T>A)--were significantly associated with CD in the case control sample. Analysis of the evolution of CARD15 revealed strong conservation of the encoded protein, with identity to the human sequence ranging from 99.1% in the chimp to 44.5% in fugu. Higher primates possess an open reading frame (ORF) upstream of the putative initiation site in other species that encodes a further 27 N-terminal amino acids, while four regions of high conservation are observed outside of the known domains of CARD15, indicative of additional residues of functional importance. The strategy developed here may have general application to the assessment of mutation pathogenicity and genetic models in other complex disorders.
Assuntos
Doença de Crohn/genética , Evolução Molecular , Predisposição Genética para Doença , Mutação/genética , Proteína Adaptadora de Sinalização NOD2/genética , Seleção Genética , Alelos , Sequência de Aminoácidos , Animais , Estudos de Casos e Controles , Análise Mutacional de DNA , Éxons/genética , Testes Genéticos , Genótipo , Humanos , Íntrons/genética , Dados de Sequência Molecular , Proteína Adaptadora de Sinalização NOD2/química , Primatas/genéticaRESUMO
Coeliac disease (CeD) is a highly heritable common autoimmune disease involving chronic small intestinal inflammation in response to dietary wheat. The human leukocyte antigen (HLA) region, and 40 newer regions identified by genome wide association studies (GWAS) and dense fine mapping, account for â¼40% of the disease heritability. We hypothesized that in pedigrees with multiple individuals with CeD rare [minor allele frequency (MAF) <0.5%] mutations of larger effect size (odds ratios of â¼2-5) might exist. We sequenced the exomes of 75 coeliac individuals of European ancestry from 55 multiply affected families. We selected interesting variants and genes for further follow up using a combination of: an assessment of shared variants between related subjects, a model-free linkage test, and gene burden tests for multiple, potentially causal, variants. We next performed highly multiplexed amplicon resequencing of all RefSeq exons from 24 candidate genes selected on the basis of the exome sequencing data in 2,248 unrelated coeliac cases and 2,230 controls. 1,335 variants with a 99.9% genotyping call rate were observed in 4,478 samples, of which 939 were present in coding regions of 24 genes (Ti/Tv 2.99). 91.7% of coding variants were rare (MAF <0.5%) and 60% were novel. Gene burden tests performed on rare functional variants identified no significant associations (p<1×10(-3)) in the resequenced candidate genes. Our strategy of sequencing multiply affected families with deep follow up of candidate genes has not identified any new CeD risk mutations.
Assuntos
Doença Celíaca/genética , Exoma , Estudos de Casos e Controles , Feminino , Seguimentos , Frequência do Gene , Ligação Genética , Predisposição Genética para Doença , Humanos , Masculino , Linhagem , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNARESUMO
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of motor neurons resulting in progressive paralysis. Gene expression studies of ALS only rarely identify the same gene pathways as gene association studies. We hypothesized that analyzing tissues by matching on degree of disease severity would identify different patterns of gene expression from a traditional case-control comparison. We analyzed gene expression changes in 4 postmortem central nervous system regions, stratified by severity of motor neuron loss. An overall comparison of cases (n = 6) and controls (n = 3) identified known ALS gene, SOX5, as showing differential expression (log2 fold change = 0.09, p = 5.5 × 10(-5)). Analyses stratified by disease severity identified expression changes in C9orf72 (p = 2.77 × 10(-3)), MATR3 (p = 3.46 × 10(-3)), and VEGFA (p = 8.21 × 10(-4)), all implicated in ALS through genetic studies, and changes in other genes in pathways involving RNA processing and immune response. These findings suggest that analysis of gene expression stratified by disease severity can identify major ALS genes and may be more efficient than traditional case-control comparison.
Assuntos
Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Expressão Gênica , Estudos de Associação Genética , Idoso , Idoso de 80 Anos ou mais , Esclerose Lateral Amiotrófica/imunologia , Proteína C9orf72 , Estudos de Casos e Controles , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/patologia , Feminino , Humanos , Imunidade/genética , Masculino , Pessoa de Meia-Idade , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Proteínas Associadas à Matriz Nuclear/genética , Proteínas Associadas à Matriz Nuclear/metabolismo , Proteínas/genética , Proteínas/metabolismo , Processamento Pós-Transcricional do RNA/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Índice de Gravidade de Doença , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Cytokines are critical checkpoints of inflammation. The treatment of human autoimmune disease has been revolutionized by targeting inflammatory cytokines as key drivers of disease pathogenesis. Despite this, there exist numerous pitfalls when translating preclinical data into the clinic. We developed an integrative biology approach combining human disease transcriptome data sets with clinically relevant in vivo models in an attempt to bridge this translational gap. We chose interleukin-22 (IL-22) as a model cytokine because of its potentially important proinflammatory role in epithelial tissues. Injection of IL-22 into normal human skin grafts produced marked inflammatory skin changes resembling human psoriasis. Injection of anti-IL-22 monoclonal antibody in a human xenotransplant model of psoriasis, developed specifically to test potential therapeutic candidates, efficiently blocked skin inflammation. Bioinformatic analysis integrating both the IL-22 and anti-IL-22 cytokine transcriptomes and mapping them onto a psoriasis disease gene coexpression network identified key cytokine-dependent hub genes. Using knockout mice and small-molecule blockade, we show that one of these hub genes, the so far unexplored serine/threonine kinase PIM1, is a critical checkpoint for human skin inflammation and potential future therapeutic target in psoriasis. Using in silico integration of human data sets and biological models, we were able to identify a new target in the treatment of psoriasis.
Assuntos
Psoríase/tratamento farmacológico , Psoríase/metabolismo , Animais , Anticorpos Monoclonais/uso terapêutico , Modelos Animais de Doenças , Humanos , Interleucinas/antagonistas & inibidores , Interleucinas/toxicidade , Camundongos , Camundongos Knockout , Psoríase/induzido quimicamente , Interleucina 22RESUMO
We performed a second-generation genome-wide association study of 4,533 individuals with celiac disease (cases) and 10,750 control subjects. We genotyped 113 selected SNPs with P(GWAS) < 10(-4) and 18 SNPs from 14 known loci in a further 4,918 cases and 5,684 controls. Variants from 13 new regions reached genome-wide significance (P(combined) < 5 x 10(-8)); most contain genes with immune functions (BACH2, CCR4, CD80, CIITA-SOCS1-CLEC16A, ICOSLG and ZMIZ1), with ETS1, RUNX3, THEMIS and TNFRSF14 having key roles in thymic T-cell selection. There was evidence to suggest associations for a further 13 regions. In an expression quantitative trait meta-analysis of 1,469 whole blood samples, 20 of 38 (52.6%) tested loci had celiac risk variants correlated (P < 0.0028, FDR 5%) with cis gene expression.
Assuntos
Doença Celíaca/genética , Genes MHC Classe I , Polimorfismo de Nucleotídeo Único , Estudos de Casos e Controles , Expressão Gênica , Perfilação da Expressão Gênica , Estudo de Associação Genômica Ampla , Humanos , Metanálise como Assunto , RiscoRESUMO
BACKGROUND & AIMS: A genome-wide association scan of nonsynonymous DNA polymorphisms identified association of a threonine-to-alanine substitution (T300A) in the autophagy-related 16-like gene ATG16L1 with Crohn's disease. We investigated this association in independent U.K. cohorts of Crohn's disease and ulcerative colitis. METHODS: The T300A variant (rs2241880) was genotyped in an independent sample of 727 Crohn's disease and 877 ulcerative colitis cases, and in 579 controls. We then performed an extension analysis combining these data with the U.K. data from the initial study to give a total of 1236 U.K. Crohn's disease cases and 1235 controls to estimate disease risk and test for interaction with the CARD15 and IBD5 risk loci and for association with disease subtypes. RESULTS: The association of T300A was replicated in the independent sample of 727 Crohn's disease cases (P = .001), and was strongly associated in the extended analysis of 1236 Crohn's cases (P = 2.4 x 10(-6)). The 300A/A genotype conferred a 1.65-fold risk of Crohn's disease, with a 2.2-fold risk of ileal disease. Analysis of the interaction of ATG16L1 with CARD15 and IBD5 indicated that all 3 loci contribute independently to disease risk. Homozygosity for the risk allele at all 3 loci conferred a combined risk of 20.4 (95% confidence interval: 8.71, 47.7) for Crohn's disease. The ATG16L1 risk genotype showed a modest but significant association with ulcerative colitis (P = .026). CONCLUSIONS: The association of ATG16L1 with Crohn's disease and possibly with ulcerative colitis supports a role for autophagy in the pathogenesis of inflammatory bowel disease.
Assuntos
Proteínas de Transporte/genética , Cromossomos Humanos Par 5/genética , Doença de Crohn/genética , Predisposição Genética para Doença/genética , Ileíte/genética , Proteína Adaptadora de Sinalização NOD2/genética , Polimorfismo de Nucleotídeo Único/genética , Adolescente , Adulto , Idoso , Autofagia/genética , Autofagia/fisiologia , Proteínas Relacionadas à Autofagia , Criança , Pré-Escolar , Estudos de Coortes , Colite Ulcerativa/genética , Doença de Crohn/fisiopatologia , Epistasia Genética , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Genéticos , Fatores de Risco , Reino UnidoRESUMO
Heritable predisposition to inflammatory bowel disease (IBD) has been demonstrated by epidemiological and genetic analysis. Linkage of IBD to broad regions of chromosome 16 has been established by analysis of multiple populations. NOD2, located on proximal 16q, was recently identified as an IBD gene. As the linkage regions on chromosome 16 are large, we have investigated the possibility that NOD2 is not the only IBD gene located on this chromosome. A high-density experiment using 39 microsatellite markers was performed to identify additional regions of association, and to indicate areas of interest for further investigation. A triple-peaked configuration of the linkage curve with peak logarithm of odds (lod) scores of 2.7, 3.2, and 3.1 was observed on proximal 16p, proximal 16q, and central 16q, respectively. The cohort was stratified by coding individuals carrying the NOD2 single nucleotide polymorphism (SNP)8 and SNP13 "unknown." Significance at the central peak, corresponding to the genomic location of NOD2, then decreased from 3.2 to 1.2. The maximal lod scores on the proximal p-arm (lod = 2.1) and central q-arm (lod = 2.6) changed only moderately. An exploratory association analysis (TRANSMIT) yielded a strong lead at D16S3068 (P = 0.00028). The region around this marker was further investigated by using anonymous SNPs. An associated haplotype containing three SNPs was identified (peak significance P = 0.00027, IBD phenotype). On stratification based on NOD2 genotype, this significance increased to P = 0.0001. These results confirm the importance of NOD2 and provide evidence for a second IBD gene located on chromosome 16p.
Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/fisiologia , Cromossomos Humanos Par 16 , Doenças Inflamatórias Intestinais/genética , Peptídeos e Proteínas de Sinalização Intracelular , Análise Mutacional de DNA , Saúde da Família , Feminino , Ligação Genética , Predisposição Genética para Doença , Genótipo , Haplótipos , Humanos , Escore Lod , Masculino , Repetições de Microssatélites , Proteína Adaptadora de Sinalização NOD2 , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Crohn's disease is a heterogeneous disorder for which NOD2 (CARD 15) has been identified as a susceptibility gene. We investigate the relation between NOD2 genotype and phenotypic characteristics of patients with Crohn's disease. METHODS: Hypotheses about the relation between NOD2 genotype and Crohn's disease phenotype were generated retrospectively from a group of 446 German patients with this disorder. Positive findings (p<0.10) were verified in prospectively established cohorts of 106 German and 55 Norwegian patients with Crohn's disease. All patients were genotyped for the main coding mutations in NOD2, denoted SNP8, SNP12, and SNP13, with Taqman technology. FINDINGS: In the retrospective cohort, six clinical characteristics showed noteworthy haplotype association: fistulising, ileal, left colonic and right colonic disease, stenosis, and resection. In the German prospective cohort, these haplotype associations could be replicated for ileal (p=0.006) and right colonic disease (p < or =0.001). A similar trend was noted in the Norwegian patients. INTERPRETATION: We recorded a distinct relation between NOD2 genotype and phenotype of Crohn's disease. Test strategies with NOD2 variations to predict the clinical course of Crohn's disease could lead to the development of new therapeutic paradigms.
Assuntos
Proteínas de Transporte/genética , Doença de Crohn/genética , Peptídeos e Proteínas de Sinalização Intracelular , Distribuição de Qui-Quadrado , Cromossomos Humanos Par 16 , Estudos de Coortes , Feminino , Predisposição Genética para Doença , Genótipo , Alemanha , Haplótipos , Humanos , Masculino , Proteína Adaptadora de Sinalização NOD2 , Noruega , Fenótipo , Estudos Retrospectivos , Fatores de RiscoRESUMO
BACKGROUND & AIMS: Mutations in the NOD2 gene are strongly associated with susceptibility to Crohn's disease (CD). We analyzed a large cohort of European patients with inflammatory bowel disease to determine which mutations confer susceptibility, the degree of risk conferred, their prevalence in familial and sporadic forms of the disease, and whether they are associated with site of disease. METHODS: Individuals were genotyped for 4 NOD2 mutations: P268S, R702W, G908R, and 3020insC. Allelic transmission distortion to 531 CD- and 337 ulcerative colitis-affected offspring was assessed by the transmission disequilibrium test. Association was also tested in an independent cohort of 995 patients with inflammatory bowel disease and 290 controls. Cases were stratified by disease site and compared across NOD2 genotypes. RESULTS: R702W, G908R, and 3020insC were strongly associated with CD but not with ulcerative colitis. Linkage disequilibrium was observed between P268S and the other mutations, forming 3 independent disease haplotypes. Genotype relative risks were 3.0 for mutation heterozygotes and 23.4 for homozygotes or compound heterozygotes. The frequency of NOD2 mutations was higher in cases from families affected only with CD and was significantly increased in ileal-specific disease cases compared with colon-specific disease (26.9% vs. 12.7%, P = 0.0004). CONCLUSIONS: The R702W, G908R, and 3020insC mutations are strong independent risk factors for CD and are associated particularly with ileal disease.
Assuntos
Proteínas de Transporte , Doença de Crohn/genética , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas/genética , Estudos de Coortes , Colo/patologia , Doença de Crohn/epidemiologia , Doença de Crohn/patologia , Saúde da Família , Feminino , Mutação da Fase de Leitura , Ligação Genética , Predisposição Genética para Doença , Humanos , Íleo/patologia , Masculino , Mutação de Sentido Incorreto , Proteína Adaptadora de Sinalização NOD2 , Fenótipo , Polimorfismo de Nucleotídeo Único , Fatores de RiscoRESUMO
A common haplotype spanning 250 kb in the cytokine gene cluster on chromosome 5q31 has recently been reported to be strongly associated with Crohn disease (CD) in Canadian families. We have replicated this finding by both the transmission-disequilibrium test (TDT) (P=.016) and in a case-control association study (P=.008) in a large European cohort of patients with CD, although the increase in disease risk was small (odds ratio 1.49 for homozygotes, 95% CI 1.11-2.0). No association was detected in families or individuals with ulcerative colitis (UC). Stratification of offspring with CD in the TDT sample by mutation status in the CD susceptibility gene CARD15 showed that the association with the 5q31 risk haplotype was present only in offspring with at least one of the known CARD15 disease susceptibility alleles (P=.044). The 5q31 risk haplotype frequency was 53.1% in unrelated individuals with CD who had one or two CARD15 mutations versus 43.7% in control subjects (P=.0001) but was not significantly elevated in individuals with CD who had no CARD15 mutations (45.4%, P=.41). Kaplan-Meier survival analysis of age at disease onset showed a significantly earlier onset in homozygotes for the 5q31 risk haplotype (P=.0019). These findings suggest that genetic variants at the 5q31 (IBD5) locus may hasten the onset of Crohn disease and cooperate with CARD15 in disease causation.