title: Association of presence/absence and on/off patterns of Helicobacter pylori oipA gene with peptic ulcer disease and gastric cancer risks: a meta-analysis.
abstract: BACKGROUND
  There are increasing studies examining the relationship between the status of H. pylori oipA gene and peptic ulcer disease (PUD) and gastric cancer (GC) but the results turn out to be controversial. We attempted to clarify whether oipA gene status is linked with PUD and/or GC risks.
  
  
  METHODS
  A systematically literature search was performed through four electronic databases. According to the specific inclusion and exclusion criteria, seven articles were ultimately available for the meta-analysis of oipA presence/absence with PUD and GC, and eleven articles were included for the meta-analysis of oipA on/off status with PUD and GC.
  
  
  RESULTS
  For the on/off functional status analysis of oipA gene, the "on" status showed significant associations with increased risks of PUD (OR = 3.97, 95% CI: 2.89, 5.45; P < 0.001) and GC (OR = 2.43, 95% CI: 1.45, 4.07; P = 0.001) compared with gastritis and functional dyspepsia controls. Results of the homogeneity test indicated different effects of oipA "on" status on PUD risk between children and adult subgroups and on GC risk between PCR-sequencing and immunoblot subgroups. For the presence/absence analysis of oipA gene, we found null association of the presence of oipA gene with the risks of PUD (OR = 1.93, 95% CI: 0.60, 6.25; P = 0.278) and GC (OR = 2.09, 95% CI: 0.51, 8.66; P = 0.308) compared with gastritis and functional dyspepsia controls.
  
  
  CONCLUSIONS
  To be concluded, when oipA exists, the functional "on" status of this gene showed association with increased risks for PUD and GC compared with gastritis and FD controls. However, merely investigating the presence/absence of oipA would overlook the importance of its functional on/off status and would not be reliable to predict risks of PUD and GC. Further large-scale and well-designed studies concerning on/off status of oipA are required to confirm our meta-analysis results.
authors.affiliation: Tumor Etiology and Screening Department of Cancer Institute and General Surgery, the First Affiliated Hospital of China Medical University, and Key Laboratory of Cancer Etiology and Prevention (China Medical University), Liaoning Provincial Education Department, Shenyang 110001, China. xcz1966@126.com.
authors.forename: Jingwei
authors.initials: J
authors.lastname: Liu
authors.forename: Caiyun
authors.initials: C
authors.lastname: He
authors.forename: Moye
authors.initials: M
authors.lastname: Chen
authors.forename: Zhenning
authors.initials: Z
authors.lastname: Wang
authors.forename: Chengzhong
authors.initials: C
authors.lastname: Xing
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D016481:Helicobacter Infections / Q000453:epidemiology / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D010437:Peptic Ulcer / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; C526444:OipA protein, Helicobacter pylori