Study of serum intestinal alkaline phosphatase isoenzyme in correlation with the ABO blood group system and secretory status in ulcer patients.

Serum alkaline phosphatase (AP) electrophoretic phenotype and the level of its activity inhibited by l-phenylalanine 5 mM (the stereospecific inhibitor of the intestinal AP isoenzyme) were investigated in 312 subjects (132 healthy controls, 89 patients with duodenal ulcer, 31 with gastric ulcer and 60 family members of the duodenal ulcer patients) in correlation with the ABO blood group system and secretory status. In the control subjects, those with A(II) blood group showed a predominance of the p degrees electrophoretic phenotype while phenotypes p+ and p++ were more frequent in the controls with O(I) and B(III) blood groups and in the secretory ones. In the patients with duodenal ulcer and their family members the frequency of phenotypes p+ and p+ was significantly higher than in the controls. The same distribution of frequencies was observed for the level of AP activity inhibited by l-phenylalanine. The results obtained are discussed in the light of a possible genetic linkage.