Clinical case: Childhood hypophosphatasia. Clinical Follow-Up

Abstract

Hypophosphatasia (HP) is a congenital disease, caused by mutations with loss of function in the gene ALPL that encodes the non-specific tissue isoenzyme of alkaline phosphatase (TNSALP). Its clinical expression displays considerable variability, from cases of intrauterine death due to severe alteration of bone mineralization, to cases with only early loss of teeth. We report the case of a male, diagnosed as odontohypophosphatasia at 30 months of age due to early loss of teeth and abnormally low levels of alkaline phosphatase, without signs of rickets or bone deformities. During follow-up, up to 13 years of age, he presented symptoms consistent with mild infantile HP such as tiredness when walking, lack of gait coordination, and pain in lower limbs, especially after physical activity. Due to the appearance of bimalleolar edema and poor response to treatment with calcitonin and anti-inflammatory drugs, infectious and / or rheumatic pathologies were ruled out. Periostitis without pyrophosphate crystal detection was diagnosed by tibial and fibular biopsy.
Radiological controls during follow up showed metaphyseal wrist enlargement, lack of remodeling of metacarpals, periosteal flaking in the tibia and fibula and hypomineralization in the tibial metaphysis, with “radiolucent tongues”;
characteristic of HP. In conclusion, hypophosphatasia should be considered as a clinical entity in children who present early loss
of teeth. The presentation of this clinical case is generally sufficient to make the diagnosis of childhood HP.