title: Meta-analysis of published studies identified eight additional common susceptibility loci for Crohn's disease and ulcerative colitis.
abstract: BACKGROUND
  Both ulcerative colitis (UC) and Crohn's disease (CD) have a complex etiology involving multiple genetic and environmental factors. Many genome-wide association studies (GWAS) and subsequent replication studies revealed that both diseases share some of the susceptibility loci; however, common genetic factors for both diseases are not fully elucidated. This study is aimed to identify the common genetic factors for CD and UC by a meta-analysis of published studies.
  
  
  METHODS
  We first reviewed the 10 GWAS for CD to select candidate single nucleotide polymorphisms (SNPs). Next, we performed a PubMed literature search up to June 30, 2010 and carried out a systemic review of published studies that examined the association of CD susceptibility loci in UC patients. Meta-analysis was carried out using the inverse variance-weighted method or the DerSimonian-Laird method after estimating the heterogeneity among the studies. The data for highly linked SNPs were combined. Finally, we performed a meta-analysis of 43 published studies in 45 SNPs located at 33 loci by using a total of 4852 to 31,125 subjects.
  
  
  RESULTS
  We confirmed the association of 17 reported common susceptibility loci. Moreover, we found associations at eight additional loci: GCKR, ATG16L1, CDKAL1, ZNF365, LRRK2-MUC19, C13orf31, PTPN2, and SBNO2. The genetic risk of each locus was modest (odds ratios ranged from 1.05-1.22) except IL23R.
  
  
  CONCLUSIONS
  These results indicate that CD and UC share many susceptibility loci with small genetic effect. Our data provide further understanding of the common pathogenesis between CD and UC.
authors.affiliation: Laboratory for Genotyping Development, Center for Genomic Medicine, RIKEN, Yokohama Institute, Japan; Department of Medicine and Clinical Science, Kyushu University, Fukuoka, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Umeno
authors.forename: Kouichi
authors.initials: K
authors.lastname: Asano
authors.forename: Tomonaga
authors.initials: T
authors.lastname: Matsushita
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kiyohara
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Iida
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kamatani
authors.forename: Michiaki
authors.initials: M
authors.lastname: Kubo
mesh_terms: D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000235:genetics*; D003424:Crohn Disease / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D015894:Genome, Human; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012307:Risk Factors