Hypophosphatasia in children and adolescents: clinical features and treatment

Hypophosphatasia (HPP) is a rare genetic disease due to loss of function mutations in the gene that encodes for Alkaline Phosphatase-Liver (ALPL) that encodes for tissue non-specific alkaline phosphatase (TNSALP) or ALP. Juvenile HPP is, by definition, diagnosed between 6 months of age and adulthood. The clinical signs and symptoms of juvenile HPP are very heterogeneous in their presentation, severity and course. The bone (impaired bone mineralization, leg deformations, pain, rickets, growth abnormalities) and dental (premature loss of deciduous teeth) abnormalities are the best known. However, in juveniles, muscular and joint abnormalities are frequently predominant. Treatment options currently remain limited to the symptomatic treatment of pain and impaired function. Promising results of the enzyme replacement therapy have been demonstrated in severely affected children with HPP. Efficacy and long term benefits in patients affected with the juvenile form are still to be proven.