[Hypophosphatasia: new therapeutic approaches].

Hypophosphatasia is a rare inborn error of metabolism characterized by a deficiency of tissue non-specific alkaline phosphatase (bone, liver and kidney) which leads to abnormal mineralization of skeletal and dental tissues. There are several forms of hypophosphatasia with wide variations in severity ranging from high-mortality neonatal presentation to mild forms in adults associated with fragility fractures and osteomalacia. The biochemical diagnosis is based on measurement of low levels of serum alkaline phophatase and increased serum or urine concentrations of phosphoethalnolamine, pyridoxal 5'-phosphate and inorganic pyrophosphate. To date, therapy has been quite heterogeneous with quite limited outcomes. The recent progress in research leads to new therapeutic approaches for this complex disease. The administration of parathyroid hormone in adult hypophosphatasia and enzyme replacement therapy using a novel soluble recombinant form of human alkaline phosphatase for severe forms of hypophosphatasia are currently the most promising approaches.