Rare Metabolic Disorders: Pediatric Form of Hypophosphatasia with Predominantly Neuropsychiatric Manifestations

Background: many congenital metabolic disorders affect the functioning of the central nervous system, leading to cognitive deficits and intellectual disability in the child. Hypophosphatasia (HF), a rare inherited disorder caused by mutations in the tissue-nonspecific alkaline phosphatase (TNSAP) gene, is one of such diseases. Mutations in the TNSAP gene, the ALPL gene, result in decreased activity of this enzyme. HF is a progressive disease with onset at any age with a wide range of symptoms. The main symptom is disorder of bone mineralization. The diversity of clinical manifestations of HF affects various organs and tissues, and the severity of the disease can range from mild, virtually asymptomatic, to severe, including lethal forms. The milder the course of the disease, the more variable and atypical the symptoms of HF can be, making timely diagnosis difficult. Patient and Method: this article describes a clinical case of HF with predominantly neurologic and psychopathologic symptoms in a child of 8 years old. Discussion: this clinical case, characterized at the clinical, biochemical and molecular genetic level, is interesting from the point of view of the atypical course of the disease with the predominance of neuropsychiatric disorders. Among all the manifestations of the disease, intellectual disability and cyclic unmotivated vomiting were the most significant and impaired adaptation. The vomiting led to a life-threatening somatic condition of the child and prolonged hospitalization in the gastroenterology department of a somatic hospital with parenteral nutrition using, where a decrease in the levels of TNSAP was randomly detected. Conclusion: it seems advisable to increase the level of awareness and alertness of neurologists and psychiatrists regarding congenital metabolic disorders, as well as to conduct laboratory screening of TNSAP levels in children.

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