title: Associations between vitamin D receptor polymorphisms and susceptibility to ulcerative colitis and Crohn's disease: a meta-analysis.
abstract: BACKGROUND
  Several polymorphisms have been identified in the vitamin D receptor (VDR) gene, while their roles in the incidence of ulcerative colitis (UC) and Crohn's disease (CD) are conflicting. This meta-analysis was designed to clarify the impact of these polymorphisms on UC and CD risk.
  
  
  METHODS
  The PubMed, Embase, and Cochrane electronic databases were searched from February 1995 to August 2011 for studies on the four VDR polymorphisms: TaqI, BsmI, FokI, and ApaI. Data were extracted and pooled odd ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.
  
  
  RESULTS
  Nine studies were included. In Asians, the ff genotype of FokI was associated with increased UC risk (OR = 1.65; 95% CI, 1.11- 2.45). The "a" allele carrier status of ApaI appeared to be a protective factor for CD (OR = 0.81; 95% CI, 0.67-0.97). The tt genotype increased the risk of CD in Europeans (OR = 1.23; 95% CI, 1.02-1.49). Moreover, the tt genotype of TaqI in males had a moderate elevated risk of UC (OR = 1.56; 95% CI, 1.02-2.39) and CD (OR = 1.84; 95% CI, 1.19-2.83).
  
  
  CONCLUSIONS
  The meta-analysis reveals a significant increase in CD risk for Europeans carrying TaqI tt genotype and a significant decrease in CD risk for all carriers of the Apal "a" allele. For Asians, the VDR FokI polymorphism appears to confer susceptibility to UC. For males, the TaqI tt genotype is associated with susceptibilities to both UC and CD. Our study explored the genetic risk prediction in UC and CD, and may provide valuable insights into IBD therapy.
authors.affiliation: Department of Gastroenterology, Changzhou No 2 Hospital, Affiliated with Nanjing Medical University, Changzhou City, Jiangsu Province, China.
authors.forename: Le-Ning
authors.initials: LN
authors.lastname: Xue
authors.forename: Ke-Qun
authors.initials: KQ
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Jia
authors.initials: J
authors.lastname: Wu
authors.forename: Xiao-Yong
authors.initials: XY
authors.lastname: Wang
mesh_terms: D003093:Colitis, Ulcerative / Q000209:etiology*; D003424:Crohn Disease / Q000209:etiology*; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D011110:Polymorphism, Genetic / Q000235:genetics*; D011379:Prognosis; D018167:Receptors, Calcitriol / Q000235:genetics*; D012307:Risk Factors
chemical_list: D018167:Receptors, Calcitriol