Brain amino acid abnormalities in pyruvate carboxylase deficiency

Amino acids were measured in several regions of autopsied brain from an infant who died with congenital lactic acidosis due to pyruvate carboxylase deficiency (McKusick 26615), as well as in cerebrospinal fluid (CSF) and plasma of four living infants with this disorder. Glutamine content was greatly reduced in all brain regions, while glutamic acid and proline contents were elevated. The gamma-aminobutyric acid (GABA) content was normal in brain. Glutamine concentrations in CSF and plasma were also decreased in the living patients. Glutamine may serve as a pool to provide glutamate and GABA for use as neurotransmitters, and to provide alpha-ketoglutarate for the tricarboxylic acid cycle when oxaloacetate can no longer be formed directly from pyruvate.