Genetic heterogeneity of combined gastric and duodenal ulcers detected by pepsinogen C gene polymorphism.

It has been reported recently that there was genetic heterogeneity in gastric ulcer disease depending upon the location of the ulcer, and that there was a significant association between the restriction fragment length polymorphism (RFLP) for pepsinogen C (PGC) gene and gastric body ulcer. In the present study, the association of the RFLP for PGC gene with combined gastric and duodenal ulcers was investigated to analyse genetic factors in its aetiology. Eighty unrelated controls and 47 patients with combined gastric and duodenal ulcers were studied. The allele frequencies of the large (3.6 kilobase EcoRI fragment) and the small fragment (3.5 kilobase EcoRI fragment) were, respectively 80.6 and 19.4% in controls, 60.0 and 40.0% in patients with combined gastric body and duodenal ulcers, 69.0 and 31.0% in patients with combined gastric angular and duodenal ulcers, and 81.8 and 18.2% in patients with combined gastric antral and duodenal ulcers. The allele frequency of the small fragment was significantly higher in patients with combined gastric body and duodenal ulcers than in controls. The genotypes that possessed the small fragment were significantly more frequent in patients with combined gastric body and duodenal ulcers (66.7%) than in controls (33.8%) and combined gastric antral and duodenal ulcers (27.3%). These results suggest that there is genetic heterogeneity in combined gastric and duodenal ulcers depending upon the location of gastric ulcer, and that combined gastric body and duodenal ulcers are associated with the small fragment allele of the PGC RFLP in the same way as solitary gastric body ulcers.