[A case of severe periodontal disease in adolescence associated with hypophosphatasia].

Hypophosphatasia is an inherited disorder characterized by defective bone mineralization, deficiency of alkaline phosphatase (ALP) activity, increased excretion of phosphoethanolamine (PEA) in the urine and premature loss of the deciduous teeth. A male hypophosphatasia patient aged 15 years 6 months, with premature exfoliation of the deciduous teeth and manifesting severe periodontal destruction in the permanent dentition, was examined. Antibody titers against seven strains by the enzyme-linked immunosorbent assay (ELISA), monocyte and neutrophil chemotaxis studies and cellular immunity tests were performed. Low levels of ALP in serum and PEA in the urine were found. Radiographic examination showed a similar pattern of alveolar bone loss to that of the localized juvenile periodontitis. Suppressed monocyte and neutrophil chemotaxis were not detected. Slightly depressed CD2+, CD3+ and CD4+ and slightly elevated activity of NK cells were found. An elevated level of antibody to Porphyromonas gingivalis was observed and this antibody titer was decreased by periodontal treatments. The affected sites of the patient showed resistance to conventional periodontal therapy. P. gingivalis was estimated to associate as an important pathogen in the etiology of periodontal destruction in this hypophosphatasia patient in addition to the dental abnormalities such as abnormal enamel, dentin, or cementum formation.