Benign inherited hyperphosphatasemia of intestinal origin: report of two cases and a brief review of the literature.

Two families with benign hyperphosphatasemia of intestinal origin were studied and compared with six other cases reported in the literature. No evidence of clinical abnormalities or explanations for the unusual enzyme concentrations were found. Agarose gel electrophoresis of alkaline phosphatase (ALP, EC 3.1.3.1) isoenzymes in serum demonstrated markedly increased intestinal isoforms (the "soluble" and the "hydrophobic" forms), which accounted for approximately 60% of total ALP activity. The description of these families demonstrated patterns suggesting autosomal-dominant inheritance, even if the precise genetic background of the abnormality affecting the enzyme production or the control mechanisms for its entry into the circulation could not be determined. Exact recognition of this benign biochemical abnormality should help to avoid unnecessary investigation.