Huntington's Chorea

Amino acids and related compounds were measured in various regions of brain obtained at autopsy from eight neurologically normal persons, one patient with Parkinson's disease, and eight patients with Huntington's chorea. γ-Aminobutyric acid (GABA) and homocarnosine, a related dipeptide, were reduced in the substantia nlgra, putamen-globus-pallidus, and caudate nucleus of the choreic patients, as compared to the normal subjects and the patient with Parkinsonism. Glycerophosphoethanolamine concentration was elevated in these three regions of choreic brain. Deficiency of γ-aminobutyric acid, a possible inhibitory synaptic transmitter in brain, might produce the symptoms characteristic of Huntington's chorea. Such a deficiency could result from reduced activity of the enzyme glutamic acid decarboxylase, or might reflect a decrease in the number of neurons that normally utilize γ-aminobutyric acid as a transmitter.