Association between genetic polymorphism of the pepsinogen C gene and gastric body ulcer: the genetic predisposition is not associated with Helicobacter pylori infection.

BACKGROUND AND AIMS

The genetic trait plays a part in the pathogenesis of peptic ulcer disease. To identify a DNA marker for peptic ulcer disease, the association between the restriction fragment length polymorphism (RFLP) of the pepsinogen C (PGC) gene and peptic ulcer disease was investigated.

PATIENTS AND METHODS

One hundred and seventy seven unrelated controls, 75 patients with gastric ulcer, and 70 with duodenal ulcer were studied. PGC-RFLP was analysed by polymerase chain reaction (PCR), and the association between PGC-RFLP and peptic ulcer disease was examined. The relation between the genetic association of PGC polymorphism with peptic ulcer and Helicobacter pylori infection was also examined.

RESULTS

Four alleles, 480 (allele 1), 450 (allele 2), 400 (allele 3), and 310 bp (allele 4), were detected by PCR. The frequency of allele 4 was significantly higher in patients with gastric body ulcer than in controls (chi (2) = 9.92, p < 0.005). Genotypes containing allele 4 were significantly more frequent in patients with gastric body ulcer than in controls and patients with gastric angular or antral ulcer. The relative risk of gastric body ulcer associated with the presence of allele 4, compared with its absence, was 4.63 and was statistically significant (chi (2) = 14.84, p < 0.005). There were no significant differences in the allelic frequencies between H pylori positive and H pylori negative groups in controls, patients with gastric body ulcer, or patients with gastric angular or antral ulcer. Both in H pylori negative and H pylori positive cases, there was an increased frequency of allele 4 in patients with gastric body ulcer compared with controls.

CONCLUSIONS

These results suggest that there is a significant association between this genetic polymorphism at the PGC gene locus and gastric body ulcer. There are differences in the genetic aetiology between gastric body ulcer and gastric angular or antral ulcer. PGC-RFLP may be used as a genetic marker for a genetic predisposition to gastric body ulcer; this genetic predisposition is not associated with H pylori infection.