Hypophosphatasia: a developmental anomaly of alkaline phosphatase?

Extract: This report deals with quantitative and qualitative investigations of alkaline phosphatase in two unrelated infants with the severe infantile form of hypophosphatasia. Both affected infants had no detectable leukocyte alkaline phosphatase activities and both sets of parents and one sibling tended to have low but variable leukocyte enzyme activities. Normal duodenal juice alkaline phosphatase activity was present in the one patient in whom it was measured and a wide range of variation in enzymic activity was observed in the stools. There was no significant difference in the stool enzyme activity between both patients with hypophosphatasia (42.01 ± 9.77 U) and control infants (40.55 ± 6.29 U). However, the heterozygous parents had values significantly lower than the control adults (2.10 ± 0.47 as compared with 19.10 ± 4.44 U). Intestinal bacteria did not contribute significantly to the stool alkaline phosphatase activity. Enzyme activity was present in the bile of one of the patients and nearly absent in that of the other.