GABA, the major inhibitory neurotransmitter in the vertebrate brain, mediates neuronal inhibition by binding to the GABA/benzodiazepine receptor and opening an integral chloride channel. Defects in GABRG2 are the cause of childhood absence epilepsy type 2 (ECA2). ECA2 is a subtype of idiopathic generalized epilepsy (IGE) characterized by an onset at age 6-7 years, frequent absence seizures (several per day) and bilateral, synchronous, symmetric 3-Hz spike waves on EEG. During adolescence, tonic-clonic and myoclonic seizures develop. Some individuals manifest ECA2 occurring in combination with febrile convulsions. Defects in GABRG2 are the cause of familial febrile convulsions type 8 (FEB8). A febrile convulsion is defined as a seizure event in infancy or childhood, usually occurring between 6 months and 6 years of age, associated with fever but without any evidence of intracranial infection or defined pathologic or traumatic cause. Febrile convulsions affect 5-12% of infants and children up to 6 years of age. There is epidemiological evidence that febrile seizures are associated with subsequent afebrile and unprovoked seizures in 2% to 7% of patients. Defects in GABRG2 are the cause of generalized epilepsy with febrile seizures plus type 3 (GEFS+3). Generalized epilepsy with febrile seizures-plus refers to a rare autosomal dominant, familial condition with incomplete penetrance and large intrafamilial variability. Patients display febrile seizures persisting sometimes beyond the age of 6 years and/or a variety of afebrile seizure types. GEFS+ is a disease combining febrile seizures, generalized seizures often precipitated by fever at age 6 years or more, and partial seizures, with a variable degree of severity. Defects in GABRG2 are a cause of severe myoclonic epilepsy in infancy (SMEI); also called Dravet syndrome. SMEI is a rare disorder characterized by generalized tonic, clonic, and tonic-clonic seizures that are initially induced by fever and begin during the first year of life. Later, patients also manifest other seizure types, including absence, myoclonic, and simple and complex partial seizures. Psychomotor development delay is observed around the second year of life. SMEI is considered to be the most severe phenotype within the spectrum of generalized epilepsies with febrile seizures-plus. Belongs to the ligand-gated ion channel (TC 1.A.9) family. Gamma-aminobutyric acid receptor (TC 1.A.9.5) subfamily. GABRG2 sub-subfamily. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Protein type: Transporter, ion channel; Membrane protein, integral; Transporter; Membrane protein, multi-pass; Channel, chloride; Channel, ligand-gated
Chromosomal Location of Human Ortholog: 5q34
Cellular Component: postsynaptic membrane; integral to plasma membrane; axon; cytoplasm; plasma membrane; cell junction
Molecular Function: protein binding; chloride channel activity; GABA-A receptor activity; benzodiazepine receptor activity; extracellular ligand-gated ion channel activity
SS: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.