Huntington's disease. Cerebrospinal fluid GABA levels in at-risk individuals.

Gamma-aminobutyric acid (GABA) was measured by the ion-exchange fluorometric method in CSF from 22 individuals at risk for Huntington's disease (HD), six individuals with HD, and five neurologically normal controls. The mean (+/- SD) GABA level in the specimens from patients with HD was 142 +/- 27 pmoles/ml, whereas that of the normal control specimens was 297 +/- 87 pmoles/ml. The mean GABA level of the specimens from the individuals at risk for HD was 209 +/- 79 pmoles/ml; however, nine of these were in the normal range with a mean value of 281 +/- 72 pmoles/ml, while the other 13 were below the normal range with a mean value of 159 +/- 27 pmoles/ml. The data indicate that low GABA levels in CSF are evident prior to the onset of symptoms of HD but a predictive value can only be determined by continued observation of the clinical course of these at-risk individuals.