free and total gamma-aminobutyric acid ( gaba ) and homocarnosine concentrations were measured in the lumbar cerebrospinal fluid ( csf ) of patients with friedreich 's ataxia , huntington 's chorea , and parkinson 's disease ( with and without levodopa treatment ) , and compared with those determined in control subjects .
C0030567
parkinson 's disease
C0023570
levodopa