Development of a novel method to detect Helicobacter pylori cagA genotype from paraffin-embedded materials: comparison between patients with duodenal ulcer and gastric cancer in young Japanese

Abstract

Background/aim: cagA gene polymorphism of Helicobacter pylori contributes to clinical outcome of patients. We investigated the implication of the cagA polymorphism in young Japanese patients using paraffin-embedded sections.

Methods: We studied 71 young patients with gastric cancer or with duodenal ulcer. H. pylori infection was confirmed by sections with Giemsa staining and immunohistochemical staining and the degree of gastritis was evaluated. DNA was extracted from paraffin-embedded sections of 20 patients both from the gastric corpus and the antrum. A portion of cagA gene was amplified with polymerase chain reaction, followed by direct sequencing of the fragment.

Results: We established a novel method to determine the cagA subtype using paraffin-embedded sections. We found that all the samples possessed East-Asian type cagA both in the corpus and the antrum, not only in patients with gastric cancer but also with duodenal ulcer. Although the cagA gene sequence was completely identical between the gastric corpus and the antrum in all patients, the corpus gastritis was more prominent in patients with gastric cancer than those with duodenal ulcer.

Conclusions: cagA polymorphism can be evaluated with the use of paraffin-embedded sections. The degree of corpus gastritis may not be regulated by cagA diversity only.