Elevated plasma gamma-aminobutyric acid (GABA) levels in individuals with either Prader-Willi syndrome or Angelman syndrome

Abstract

Plasma gamma-aminobutyric acid (GABA) levels were measured in 14 subjects with Prader-Willi syndrome, 9 subjects with Angelman syndrome, and matched control subjects. Mean levels in both patient groups were 2 to 3 times higher than in nonretarded moderately obese or retarded nonobese control subjects. Levels in each patient group differed significantly from both control groups. Neither the two patient groups nor the two control groups differed. GABA levels seemed unrelated to genetic status (chromosome 15 deletion or disomy). These preliminary findings of elevated plasma GABA levels possibly represent a compensatory increase in presynaptic GABA release in response to hyposensitivity of a subset of GABA receptors and could produce increased postsynaptic activation of other normal GABA receptor subtypes, resulting in complex alterations of GABAergic function throughout the brain.

FIGURE 1

Plasma γ-aminobutyric acid (GABA) levels in Prader-Willi syndrome (PWS), Angelman syndrome (AS), and control subjects. Individual data and mean values of plasma GABA levels (pmol/ml plasma) as determined by high-performance liquid chromatographic (HPLC) analysis are presented. The mean values of both the PWS and the AS subjects were significantly different from those of the controls (mentally retarded nonobese and non–mentally retarded moderately obese subjects), but no difference was found between non–mentally retarded moderately obese and mentally retarded nonobese subjects. Subject numbers correspond to the subject numbers in Table 1.