ESPE Abstracts

Background: Hypophosphatasia (HP) is a rare inherited disorder characterized by defective bone and tooth mineralization and caused by deficiency in the tissue non-specific alkaline phosphatase gene (ALPL). The symptoms are remarkably variable in their clinical expression, and relate to numerous mutations in this gene.

Aim: The purpose of this study was to document the clinical, biochemical and radiologic aspects of the three relative patients (two sibling and their one cousin) with childhood hypophosphatasia carrying the same mutation gene.

Methods: Clinical and radiographic examinations were carried out. We collected medical and dental history in the kindred and biochemical data. Finally, mutations in the ALPL gene were tested by DNA sequencing.

Results: Low levels of alkaline phosphatase (ALP) in serum and phosphoethanolamine (PEA) in the urine were found. Affected our patients have a history of delayed walking. Bone pain (due to stress fractures) and joint pain (due to deposition of calcium pyrophosphate dihydrate) were a frequent symptom in the our patients. Characteristic dental symptoms were premature deciduous teeth loss, premature exfoliation of fully rooted primary teeth, severe dental caries, root resorbsion and alveolar bone loss. Clinical and radiologic examinations revealed delayed eruption of permanent teeth and large pulp chambers of all first permanent molars.

Conclusion: Even in two sibling and cousin who share the same mutations, there may be significant differences in the HPP table and severity. A good co-operation between pediatrist and dentist is need for a better management of the patients. The dentist plays a critical role in the detection and early diagnosis of the disease.