Pediatric neurotransmitter diseases.

The pediatric neurotransmitter disorders represent a challenging group of rare neurometabolic disorders classified on the basis of alterations in neurotransmitter metabolic pathways. The disorders are currently classified into disturbances of monoamine and gamma-aminobutyric acid (GABA) metabolism, although disorders of other neurotransmitters, such as glutamate and melatonin, may well be recognized in future investigations. This review summarizes the clinical and laboratory features of selected pediatric neurotransmitter disorders that have been partially delineated. Of the monoamine group, these are Segawa disease or guanosine triphosphate-cyclohydrolase I deficiency, aromatic L-amino acid decarboxylase deficiency, and tyrosine hydroxylase deficiency. Of the GABA disorders, these are pyridoxine-dependent epilepsy, GABA transaminase deficiency, and succinic semialdehyde dehydrogenase deficiency. As proper collection, handling, and interpretation of cerebrospinal fluid is required for assessment of most of these disorders, we end by summarizing important considerations for obtaining cerebrospinal fluid samples.