Hypophosphatasia in Taiwan: report of two cases.

Hypophosphatasia is a rare inherited metabolic disease characterized by rickets with reduced plasma and tissue alkaline phosphatase activity. It may be present in infancy, childhood, or adulthood. Various clinical manifestations reflect different forms of alkaline phosphatase gene expression. In this report, we present two cases of hypophosphatasia, one of the infantile and the other of the adult form. The infantile case presented with failure to thrive, hypotonia, and radiologic rickets at 4 months old. The adult case had repeated fractures and marked loss of bone density demonstrated by radiographs. Both cases showed extremely low levels of alkaline phosphatase. To the best of our knowledge, they are the first reported patients with hypophosphatasia from the Taiwanese population.