Gamma-aminobutyric acid receptor subunit beta-3

GABRB3 encodes the beta-3 subunit of GABA(A) receptors, which are pentameric ligand-gated chloride channels fundamental to inhibitory neurotransmission in the brain (UniProt: P28472). The GABA-binding site forms at interfaces between alpha and beta subunits; upon GABA activation, chloride influx hyperpolarizes neurons and suppresses action potential generation. Beta-3-containing receptors localize to both synaptic and extrasynaptic sites, contributing to phasic and tonic inhibition respectively, and also facilitate synaptogenesis and somatosensory signaling (UniProt: P28472).

GABRB3 variants cause epilepsy-spectrum disorders. Mutations are associated with childhood absence epilepsy 5 (ECA5), characterized by onset around age 6–7 with frequent absence seizures and 3-Hz spike-wave discharges, and developmental and epileptic encephalopathy 43 (DEE43), an autosomal dominant severe early-onset epilepsy with refractory seizures and neurodevelopmental impairment (UniProt: P28472).

GABRB3 is classified as SFARI Category 2 (strong candidate) and carries syndromic annotation, indicating robust evidence for association with autism spectrum disorder in the context of epilepsy or broader developmental encephalopathy (SFARI Cat 2).