Functional evaluation of mutations in the tissue-nonspecific alkaline phosphatase gene.

The Chinese Journal of Dental Research during the process of mineralisation. This decreases PPi, which is an inhibitor of hydroxyapatite formation, and provides Pi for the formation of hydroxyapatite8. Since inorganic phosphate (Pi) is essential for hydroxyapatite formation, the normal ability of TNSALP to hydrolyse PPi to Pi is essential for bone and teeth development9–11. Hypophosphatasia is a rare inherited disease and is classified into at least 5 forms – perinatal, infantile, childhood, adult, and odontohypophosphatasia – according to disease severity and age of onset9. The perinatal form is the most severe, and often manifests in the uterus with profound skeletal hypomineralisation, and typically causes death in affected foetuses. The infantile form occurs within 6 months of birth; respiratory failure is the main cause of death. The childhood form presents within 2 years of birth and is characterised by milder symptoms, deformity of the extremities, and premature loss of primary teeth. The adult form of the disease presents during middle age, with mild symptoms. Odontohypophosphatasia is characterised 1 Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, P.R. China. 2 Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, P.R. China.