Papandreou A, McTague A, Trump N, Ambegaonkar G, Ngoh A, Meyer E, Scott RH, Kurian MA. GABRB3 mutations: a new and emerging cause of early infantile epileptic encephalopathy. Dev Med Child Neurol. 2015 Dec 9. doi: 10.1111/dmcn.12976. [Epub ahead of print]
The gamma-aminobutyric acid type A receptor β3 gene (GABRB3) encodes the β3-subunit of the gamma-aminobutyric acid type A (GABAA ) receptor, which mediates inhibitory signalling within the central nervous system. Recently, GABRB3 mutations have been identified in a few patients with infantile spasms and Lennox-Gastaut syndrome. We report the clinical and electrographic features of a novel case of GABRB3-related early-onset epileptic encephalopathy. Our patient presented with neonatal hypotonia and feeding difficulties, then developed pharmacoresistant epileptic encephalopathy, characterized by multiple seizure types from 3 months of age. Electroencephalography demonstrated ictal generalized and interictal multifocal epileptiform abnormalities. Using a SureSelectXT custom multiple gene panel covering 48 early infantile epileptic encephalopathy/developmental delay genes, a novel de novo GABRB3 heterozygous missense mutation, c.860C>T (p.Thr287Ile), was identified and confirmed on Sanger sequencing. GABRB3 is an emerging cause of early-onset epilepsy. Novel genetic technologies, such as whole-exome/genome sequencing and multiple gene panels, will undoubtedly identify further cases, allowing more detailed electroclinical delineation of the GABRB3-related genotypic and phenotypic spectra. Courtesy of: http://www.mdlinx.com/neurology/medical-news-article/2015/12/28/epileptic-encephalopathy-gabrb3-mutations/6447744/?category=sub-specialty&page_id=2&subspec_id=317 We have 2 patients with GABRG3 mutations. That's as close as we get, thus far.