Systematic review and meta-analysis: the relationship between the Helicobacter pylori dupA gene and clinical outcomes

<p>Abstract</p> <p>Background</p> <p>In 2005, the first disease-specific <it>Helicobacter pylori </it>virulence factor that induced duodenal ulcer and had a suppressive action on gastric cancer has been identified, and was named duodenal ulcer promoting gene (<it>dupA</it>). However, the importance of the <it>dupA </it>gene on clinical outcomes is conflicting in subsequent studies. The aim of this study was to estimate the magnitude of the risk for clinical outcomes associated with <it>dupA </it>gene.</p> <p>Methods</p> <p>A meta-analysis of case-control studies which provided raw data on the infection rates with the <it>dupA</it>-positive <it>H. pylori </it>detected by polymerase chain reaction was performed.</p> <p>Results</p> <p>Seventeen studies with a total of 2,466 patients were identified in the search. Infection with the <it>dupA</it>-positive <it>H. pylori </it>increased the risk for duodenal ulcer by 1.41-fold (95% confidence interval [CI], 1.12-1.76) overall. Subgroup analysis showed that the summary odds ratio (OR) was 1.57 (95% CI, 1.19-2.06) in Asian countries and 1.09 (95% CI, 0.73-1.62) in Western countries. There was no association between the presence of the <it>dupA </it>gene and gastric cancer and gastric ulcer. Publication bias did not exist.</p> <p>Conclusion</p> <p>Our meta-analysis confirmed the importance of the presence of the <it>dupA </it>gene for duodenal ulcer, especially in Asian countries.</p

Helicobacter pylori iceA, clinical outcomes, and correlation with cagA: a meta-analysis.

Although the iceA (induced by contact with epithelium) allelic types of Helicobacter pylori have been reported to be associated with peptic ulcer, the importance of iceA on clinical outcomes based on subsequent studies is controversial. The aim of this study was to estimate the magnitude of the risk for clinical outcomes associated with iceA.A literature search was performed using the PubMed and EMBASE databases for articles published through April 2011. Published case-control studies examining the relationship between iceA and clinical outcomes (gastritis, peptic ulcer, including gastric ulcer and duodenal ulcer, and gastric cancer) were included.Fifty studies with a total of 5,357 patients were identified in the search. Infection with iceA1-positive H. pylori increased the overall risk for peptic ulcer by 1.26-fold (95% confidence interval [CI], 1.09-1.45). However, the test for heterogeneity was significant among these studies. Sensitivity analysis showed that the presence of iceA1 was significantly associated with peptic ulcer (odds ratio [OR] = 1.25, 95% CI = 1.08-1.44). The presence of iceA2 was inversely associated with peptic ulcer (OR = 0.76, 95% CI = 0.65-0.89). The presence of iceA was not associated with gastric cancer. Most studies examined the cagA status; however, only 15 studies examined the correlation and only 2 showed a positive correlation between the presence of cagA and iceA1.Our meta-analysis confirmed the importance of the presence of iceA for peptic ulcer, although the significance was marginal

Association between <it>Helicobacter pylori cagA</it>-related genes and clinical outcomes in Colombia and Japan

Abstract Background Specific genotypes of several virulence factors of Helicobacter pylori (eg, cagA-positive, vacA s1, oipA "on" and babA-positive) have been reported to be predictors of severe clinical outcomes. Importantly, the presence of these genotypes correlates with each other. We hypothesized that novel virulence genes correlate with the presence of cagA. Therefore, we aimed to find novel candidate virulence genes that correlate with cagA and examined the association of these genes with clinical outcomes in Colombian and Japanese populations. Methods cagA-associated genes were selected based on previous H. pylori genome microarray data. A total of 343 strains (174 from Colombia and 169 from Japan) were examined for the status of cagA, vacA, and candidate genes by polymerase chain reaction and dot blot. Results Microarray data showed that 9 genes were significantly correlated with the presence of cagA. Among the 9 genes, the functions of 4 were known, and we selected these 4 genes as candidate genes (hp0967, jhp0045, jhp0046, and jhp0951). The prevalences of cagA, vacA s1/m1 genotype, and hp0967 were significantly higher in Japan than Colombia, whereas those of jhp0045 and jhp0046 were more prevalent in Colombia than Japan. The prevalences of jhp0045 and jhp0046 in cagA-positive cases of gastric cancer were significantly higher than those from gastritis in Colombia (P = 0.015 and 0.047, respectively). In contrast, the prevalence of 4 candidate genes was independent of clinical outcomes in Japan. Conclusions jhp0045 and jhp0046 might be novel markers for predicting gastric cancer in cagA-positive cases in Colombia, but not in Japan.</p