Inherited disorders of vitamin metabolism

Vitamins are essential cofactors of various enzyme reactions in amino acid, neurotransmitter, nucleotide and energy metabolism. Over the past decade a number of inborn errors of metabolism have been identified, that affect different steps in vitamin absorption, transport, activation or recycling and repair of active vitamin cofactors. According to the respective cofactor function this may result in acute or chronic multisystem disease or in disorders that selectively affect the nervous system. Most of these disorders are amenable to specific treatment with excellent results, but diagnostic delay can lead to rapid, irreversible damage or even death. Therefore, especially in case of acute and severe neurologic presentations compatible with one of the here discused disorders, a vitamin trial should be considered while awaiting results of biochemical and genetic testing. Diagnosis of these disorders is especially rewarding, as treatment is often per oral, available worldwide and comparably cheap. This article will review current knowledge of the clinical presentation, biomarkers and specific treatment of inborn errors of vitamin metabolism and illustrates why child neurologists should have vitamins in their pockets.