Bone Abstracts

Introduction: Hypophosphatasia is a rare genetic disease caused by a mutation in the tissue-nonspecific alkaline phosphatase gene. TNSALP gene is located on the short arm of chromosome 1 (1p36.1-34). Over 200 point mutations have been described for this gene so far. Hypophosphatasia is inherited in an autosomal recessive or dominant way, which is related to the severity of symptoms. Pathophysiology of this disease is associated with the impaired function of osteoblasts that do not incorporate calcium into the matrix of the newly formed osseous tissue. Low alkaline phosphatase activity disturbs hydroxyapatite formation. The clinical picture of the disease depends on the time of symptom emergence. Depending on the severity, 6 hypophosphatasia sub-types may be identified: perinatal, infantile, childhood, adult hypophosphatasia, odontohypophosphatasia, and pseudohypophosphatasia.

Aim: The aim of this study was to present the case of a girl with calcium-phosphate disorders, diagnosed with hypophosphatasia.

Method: Child’s medical records from birth to diagnosis and treatment administration were subject to analysis. The reason why the diagnosis was delayed in our female patient and other children described in the literature was the omission of alkaline phosphatase test interpretation; this enzyme levels have always been lowered, even with a poor clinical picture.

Conclusions:
1. Hypophosphatasia diagnosis is difficult due to a variety of forms and clinical symptoms, as well as to its occasional occurrence.

2. The diagnostics of disorders with skeletal system lesions should consider both lower and upper reference ranges of biochemical parameters, because their thorough analysis is the base for the differential diagnostics.

3. The introduction of enzyme replacement therapy leads to clinical, biochemical and radiological improvement in patients with hypophosphatasia.

Disclosure: The authors declared no competing interests.