[(11)C]flumazenil positron emission tomography analyses of brain gamma-aminobutyric acid type A receptors in Angelman syndrome.

Objective: To evaluate the role of the gamma-aminobutyric acid type A (GABA(A)) receptor in Angelman syndrome (AS).

Study Design: We performed [(11)C]flumazenil positron emission tomography (PET) and examined GABA(A) receptor expression in 7 patients with AS of various genotypes (5 with the deletion, 1 with an imprinting defect [ID], and 1 with a UBE3A mutation) and 4 normal control healthy volunteers.

Results: Relative to the control subjects, the [(11)C]flumazenil binding potentials (BPs) were significantly higher in the cerebral cortex and cerebellum in the 5 patients with the deletion and in the 1 patient with a UBE3A mutation, and were less frequently or barely increased in adult patients with the deletion and in the patient with IDs.

Conclusions: Total GABA(A) receptor expression was increased in patients with AS with various genotypes. We suggest that a developmental dysregulation of the GABA(A) receptor subunits occurs in patients with AS.