[Multiple carboxylase deficiency].

Biotinidase deficiency and holocarboxylase synthetase deficiency are two autosomal recessively inherited disorders of biotin metabolism affecting children below the age of two years. Both cause multiple carboxylase deficiency resulting in defects of fatty acid synthesis, gluconeogenesis and amino acid catabolism. The clinical picture involves the nervous system, the skin, the respiratory system, the digestive system and the immune system, but great individual variations often makes the clinical diagnosis difficult. Early diagnosis and treatment with biotin are essential in order to prevent death from metabolic acidosis or irreversible damage to the central nervous system. Two patients with biotinidase deficiency, two patients with holocarboxylase synthetase deficiency and a review of the literature are presented. Neonatal screening for biotinidase deficiency or a higher degree of metabolic screening of the urine in children below the age of one year with seizures and unexplained clinical course are discussed.