Evaluation of Helicobacter pylori vacA genotype in Japanese patients with gastric cancer.

AIM To examine the vacA genotypes of Helicobacter pylori strains in Japan and to define whether any specific genotype was associated with gastric cancer. METHODS The allelic variation of vacA gene was studied using a recently introduced polymerase chain reaction based vacA genotyping system. RESULTS 80 H pylori strains were isolated from gastric biopsies of 40 patients with gastric cancer and 40 control subjects in a Japanese population. All strains were s1/m1 subtype and 79 of 80 strains were classified as s1a subtype. CONCLUSIONS The recently proposed vacA genotyping system is applicable to Japanese H pylori strains and most strains have the s1a genotype, associated with increased virulence. While the high frequency of s1a/m1 vacA genotype might play a role in the increased incidence of atrophic gastritis and gastric cancer in Japanese subjects, it precludes its use as a predictor of clinical outcome of H pylori infection in Japan.