title: Phospholipase C beta 1 deficiency is associated with early-onset epileptic encephalopathy.
abstract: The epileptic encephalopathies of infancy and childhood are a collection of epilepsy disorders characterized by refractory, severe seizures and poor neurological outcome, in which the mechanism of disease is poorly understood. We report the clinical presentation and evolution of epileptic encephalopathy in a patient, associated with a loss-of-function mutation in the phospholipase C-β 1 gene. We ascertained a consanguineous family containing a male infant who presented with early-onset epileptic encephalopathy for detailed clinical phenotyping and molecular genetic investigation. In addition, a cohort of 12 consanguineous families of children with infantile spasms were analysed for linkage to the phospholipase C-β 1 gene locus. The male infant presented with tonic seizures in early infancy and subsequently developed infantile spasms. Over time, he developed drug-resistant epilepsy associated with severe neurological regression and failure to thrive. Molecular genetic investigation revealed a homozygous loss-of-function 0.5-Mb deletion, encompassing the promoter element and exons 1, 2 and 3 of phospholipase C-β 1 in the index case. Linkage to the phospholipase C-β 1 locus was excluded in the 12 other consanguineous families, consistent with genetic heterogeneity in this disorder. Although phospholipase C-β 1 deficiency has not previously been reported in humans, the Plcb1 homozygote knockout mouse displays early-onset severe tonic seizures and growth retardation, thus recapitulating the human phenotype. Phospholipase C-β 1 has important functions in both hippocampal muscarinic acetylcholine receptor signalling and in cortical development. Thus, the discovery of a phospholipase C-β 1 mutation allows us to propose a novel potential underlying mechanism in early-onset epileptic encephalopathy.
authors.affiliation: Department of Medical and Molecular Genetics, University of Birmingham School of Medicine, Institute of Biomedical Research, Birmingham, UK.
authors.forename: Manju A
authors.initials: MA
authors.lastname: Kurian
authors.forename: Esther
authors.initials: E
authors.lastname: Meyer
authors.forename: Grace
authors.initials: G
authors.lastname: Vassallo
authors.forename: Neil V
authors.initials: NV
authors.lastname: Morgan
authors.forename: Nandhini
authors.initials: N
authors.lastname: Prakash
authors.forename: Shanaz
authors.initials: S
authors.lastname: Pasha
authors.forename: Nebula A
authors.initials: NA
authors.lastname: Hai
authors.forename: Salwati
authors.initials: S
authors.lastname: Shuib
authors.forename: Fatima
authors.initials: F
authors.lastname: Rahman
authors.forename: Evangeline
authors.initials: E
authors.lastname: Wassmer
authors.forename: J Helen
authors.initials: JH
authors.lastname: Cross
authors.forename: Finbar J
authors.initials: FJ
authors.lastname: O'Callaghan
authors.forename: John P
authors.initials: JP
authors.lastname: Osborne
authors.forename: Ingrid E
authors.initials: IE
authors.lastname: Scheffer
authors.forename: Paul
authors.initials: P
authors.lastname: Gissen
authors.forename: Eamonn R
authors.initials: ER
authors.lastname: Maher
mesh_terms: D004569:Electroencephalography; D004827:Epilepsy / Q000235:genetics* / Q000503:physiopathology; D005183:Failure to Thrive / Q000235:genetics* / Q000503:physiopathology; D017809:Fatal Outcome; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation; D010641:Phenotype; D054799:Phospholipase C beta / Q000235:genetics*; D016133:Polymerase Chain Reaction
chemical_list: C518033:PLCB1 protein, human; D054799:Phospholipase C beta