[Biotinidase deficiency: a congenital metabolic disease which can be successfully treatment with vitamin H]

At the age of 13 months a patient developed muscular hypotonia, deafness of the inner ear and cutaneous symptoms (alopecia; skin rash, complicated by superinfection with monilia). Biochemical assays revealed compensated metabolic acidosis, pathologically high lactate and pyruvate concentrations in the blood and cerebro-spinal fluid, as well as increased urinary excretion of 3-OH-isovaleric acid, 3-methylcrotonylglycine and lactate. The patient was diagnosed as suffering from autosomal recessive biotinidase deficiency on the basis of severely reduced biotinidase activity in plasma (0.05 nmol/min/ml). In both his parents and brother heterozygosity was found. Institution of therapy with a daily dose of 10 mg biotin rapidly removed most of the symptoms; after six months of treatment the deafness had improved significantly.