[Biotinidase deficiency. Progressive encephalopathy curable with biotin].

Background: Multiple carboxylase deficiency is a rare cause of progressive encephalopathy. There are 2 forms: the neonatal-onset form of holocarboxylase synthetase deficiency and the late-onset form of biotinidase deficiency. This report describes a case of biotinidase deficiency.

Case report: A boy began to have repeated convulsions at the age of 3 months. The brain CT-scan and MRI were normal and the patient was given valproic acid and carbamazepine. Progressive neurological degradation was noted from the 4th month of life and myoclonic seizures began 2 months later. At admission, the patient had seizures, myoclonic fits and hypotonia. He had a skin rash but no alopecia. Biochemical investigation showed lactic acidosis, mainly in the CSF, moderate hyperammonemia and hyperalaninemia. Chromatography of organic acids showed several abnormal peaks suggesting biotinidase deficiency. The patient was given biotin (20 mg/day) orally. This treatment produced a pronounced, rapid, clinical and biochemical improvement and antiepileptic drugs were discontinued. There was no developmental delay at the age of 18 months.

Conclusion: The clinical findings of neurologic abnormalities and dermatological signs led to the diagnosis of a metabolic disease that, fortunately, can be treated. This disease could benefit from a mass neonatal screening program.