A new alkaline phosphatase isoenzyme abnormality

We report on a new alkaline phosphatase isoenzyme abnormality occurring as an incidental finding in a male infant aged 4 months. Isoenzyme electrophoresis on cellulose acetate showed a prominent, diffuse alkaline phosphatase staining band in the alpha 1-globulin position together with a second band in the alpha 2/beta region and minor 'trailing' in the intermediate alpha 2 region. Normal liver and bone alkaline phosphatase were absent and intestinal phosphatase was not detected. On acrylamide gel electrophoresis a marked origin band was detectable suggesting the presence of high molecular weight enzyme. In addition, a series of compact bands in the alpha 2/beta position was present cathodal to the usual liver and bone isoenzymes. Total alkaline phosphatase activity was marginally elevated and was heat labile, L-phenylalanine resistant and partially L-homoarginine and L-leucine sensitive.