dupA polymorphisms and risk of Helicobacter pylori-associated diseases

Abstract The dup A of Helicobacter pylori has been suggested as a virulence marker associated with the development of duodenal ulcer disease. However, the studies performed in different geographical areas have shown that there are variations in the prevalence of dup A and its association with H. pylori clinical outcomes. Our group did not observe associations between the presence of dup A and H. pylori clinical outcomes in Brazil. On the other hand, we observed 2 mutations in the sequence of dup A that lead to stop codons: a deletion of an adenine at position 1311 and an insertion of an adenine at position 1426 of the gene. Our aim was to evaluate associations of the presence of dup A with duodenal ulcer and gastric cancer, considering dup A-positive only those H. pylori strains that do not have the mutations in the gene sequence. We also evaluated the effect of infection with a strain carrying an intact dup A on the gastric mucosa histology and IL-8 gastric levels. Colonization with strains that had the intact dup A was negatively associated with gastric carcinoma ( p  = 0.001, OR = 0.32, 95% CI = 0.16–0.66). The presence of dup A was also associated with an increased degree of antral mucosa inflammation ( p  = 0.01) and with decreased corpus atrophy ( p p  = 0.04). In conclusion, the infection with a H. pylori strain containing the dup A without the stop codon polymorphisms is associated with a lower risk of development of gastric carcinoma in Brazilian subjects.