title: Association between the Pro12Ala polymorphism of peroxisome proliferator-activated receptor gamma 2 and inflammatory bowel disease: a meta-analysis.
abstract: BACKGROUND
  Peroxisome proliferator-activated receptor gamma (PPARγ), a nuclear receptor, has been implicated playing a role in the development of inflammatory bowel disease (IBD). However, previous studies evaluating the association between the PPARγ2 Pro12Ala polymorphism and IBD are inconsistent. We performed a meta-analysis to determine whether the PPARγ2 Pro12Ala mutation was associated with the presence of IBD.
  
  
  RESULTS
  Electronic databases were searched for case-control studies evaluating the association between the Pro12Ala mutation and the presence of IBD. Effects were summarized with the methods recommended by the Cochrane Collaboration. A total of 7 studies including 1002 ulcerative colitis (UC) cases, 1090 Crohǹs disease (CD) cases and 1983 controls were involved in this meta-analysis. In the overall analysis, no significant association of this polymorphism with UC or CD was found. In the subgroup analyses in different populations, AlaAla genotype seemed to protect the European Caucasian population against the development of CD (Pro vs Ala: OR = 1.135, 95%CI = 0.951-1.354, P = 0.162, Bon = 1.000; ProPro vs ProAla: OR = 1.042, 95%CI = 0.852-1.273, P = 0.690, Bon = 1.000; ProPro vs AlaAla: OR = 2.379, 95%CI = 1.110-5.100, P = 0.026, Bon = 0.156; ProAla vs AlaAla: OR = 2.315, 95%CI = 1.064-5.037, P = 0.034, Bon = 0.204; Pro homozygotes vs Ala positives: OR = 1.094, 95%CI = 0.899-1.330, P = 0.371, Bon = 1.000; Pro positives vs Ala homozygotes: OR = 2.360, 95%CI = 1.103-5.053, P = 0.027, Bon = 0.162; heterozygotes vs all homozygotes: OR = 0.976, 95%CI = 0.799-1.192, P = 0.809, Bon = 1.000). There was no significant association of this polymorphism with UC or CD in the East Asian population and the Turkish population.
  
  
  CONCLUSIONS
  AlaAla genotype may be a protective factor in the European Caucasian population against the development of CD in a recessive way.
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Dalian Medical University, Dalian, China. zhifeng_zhang@tom.com
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.forename: Lei
authors.initials: L
authors.lastname: Zhu
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Wang
mesh_terms: D044466:Asian People; D003424:Crohn Disease / Q000235:genetics; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics*; D008297:Male; D047495:PPAR gamma / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D044465:White People
chemical_list: D047495:PPAR gamma