GABRG2 and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Mutations in GABAA receptor subunit genes are frequently associated with epilepsy, and nonsense mutations in GABRG2 are associated with several epilepsy syndromes including childhood absence epilepsy, generalized tonic clonic seizures and the epileptic encephalopathy, Dravet syndrome.