ELEVATED PLASMA GAMMA-AMINOBUTYRIC-ACID (GABA) LEVELS IN INDIVIDUALS WITH EITHER PRADER-WILLI-SYNDROME OR ANGELMAN SYNDROME

Plasma gamma-aminobutyric acid (GABA) levels were measured in 14 subje cts with Prader-Willi syndrome, 9 subjects with Angelman syndrome, and matched control subjects. Mean levels in both patient groups were 2 t o 3 times higher than in nonretarded moderately obese or retarded nono bese control subjects. Levels in each patient group differed significa ntly from both control groups. Neither the two patient groups nov the two control groups differed. GABA levels seemed unrelated to genetic s tatus (chromosome 15 deletion or disomy). These preliminary findings o f elevated plasma GABA levels possibly represent a compensatory increa se in presynaptic GABA release in response to hyposensitivity of a sub set of GABA receptors and could produce increased postsynaptic activat ion of other normal GABA receptor subtypes, resulting in complex alter ations of GABAergic function throughout the brain.