RESUMO
BACKGROUND AND AIMS: Recent meta-analysis of genome-wide association studies have identified over 241 inflammatory bowel disease susceptibility loci. However, the known variants only account for a fraction of inflammatory bowel disease heritability. To identify additional susceptibility loci, we performed a trans-ethnic meta-analysis as well as an Asian-specific meta-analysis, using all published Immunochip association results of inflammatory bowel disease. METHODS: An inverse-variance fixed-effects meta-analysis was carried out across Korean and East Asian Immunochip datasets of 4156 cases and 4904 controls [Asian ancestry]. A trans-ethnic meta-analysis of inflammatory bowel disease was performed together with the European datasets of 38 155 cases and 48 485 controls genotyped on the immunochip using a Bayesian approach, Meta-Analysis of Trans-ethnic Association studies [MANTRA]. RESULTS: We identified seven novel associations, including three novel susceptibility loci at MYO10-BASP1, PPP2R3C/KIAA0391/PSMA6/NFKB1A and LRRK1 as well as four novel secondary associations within previously known loci at NCF4, TSPAN32, CIITA and VANGL2. The new loci further implicate alterations in B cell biology in Crohn's disease pathogenesis. The effects of five loci were universal across European and Asian ancestries, whereas the NCF4 and CIITA loci showed significant heterogeneity between European and East Asian populations. In addition, 103 previously known IBD loci showed supporting evidence of association with nominal significance [p < 0.05] in Asians. CONCLUSIONS: Our findings of new loci not previously associated with IBD support the importance of studying inflammatory bowel disease genetics in diverse populations.
Assuntos
Povo Asiático/genética , Loci Gênicos , Doenças Inflamatórias Intestinais/genética , População Branca/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Doenças Inflamatórias Intestinais/etnologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Miosinas/genética , Inibidor de NF-kappaB alfa/genética , Proteínas do Tecido Nervoso/genética , Proteínas Nucleares/genética , Fosfoproteínas/genética , Polimorfismo de Nucleotídeo Único , Complexo de Endopeptidases do Proteassoma/genética , Proteína Fosfatase 2/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Repressoras/genética , República da Coreia/etnologia , Ribonuclease P/genética , Tetraspaninas/genética , Transativadores/genéticaRESUMO
BACKGROUND AND AIM: CDKN2A/CDKN2B locus on 9p21 is reported to be associated with various diseases, including cancer and cardiovascular and inflammatory diseases. Significant downregulation of CDKN2B-AS1 in inflamed colon tissue of inflammatory bowel disease (IBD) cases was reported in Europeans. This study aimed to confirm the suggestive association of CDKN2A/CDKN2B with IBD identified in our recent genome-wide association study (GWAS). METHODS: We examined the association of CDKN2A/CDKN2B locus with IBD in an additional sample of 574 IBD cases and 542 controls, totaling 4068 cases and 8074 controls. In silico study was performed at various levels for functional annotation of the causal variant. Co-localization of the GWAS association signals and the corresponding expression quantitative trait loci in IBD-related tissues was evaluated using eCAVIAR. RESULTS: An expanded GWAS showed genome-wide significant association of rs3731257 at 9p21 with IBD (odds ratio = 1.17, 95% confidence interval = 1.12-1.22, Pcombined = 5.68 × 10-9 ) and Crohn's disease (odds ratio = 1.22, 95% confidence interval = 1.15-1.28, Pcombined = 8.85 × 10-9 ) in the Korean population. Co-localization study suggested that both CDKN2B-AS1 and CDKN2A might be functionally associated with the locus in the small intestine. CONCLUSIONS: rs3731257 in CDKN2A/CDKN2B is an IBD-susceptible locus in Koreans, with a suggestive role for small intestine-specific gene regulation. Our findings suggested that alterations of the CDKN2A/CDKN2B locus could affect the pathophysiology of IBD.