title: Characterization of two de novoKCNT1 mutations in children with malignant migrating partial seizures in infancy.
abstract: The KCNT1 gene encodes for subunits contributing to the Na(+)-activated K(+) current (KNa), expressed in many cell types. Mutations in KCNT1 have been found in patients affected with a wide spectrum of early-onset epilepsies, including Malignant Migrating Partial Seizures in Infancy (MMPSI), a severe early-onset epileptic encephalopathy characterized by pharmacoresistant focal seizures migrating from one brain region or hemisphere to another and neurodevelopment arrest or regression, resulting in profound disability. In the present study we report identification by whole exome sequencing (WES) of two de novo, heterozygous KCNT1 mutations (G288S and, not previously reported, M516V) in two unrelated MMPSI probands. Functional studies in a heterologous expression system revealed that channels formed by mutant KCNT1 subunits carried larger currents when compared to wild-type KCNT1 channels, both as homo- and heteromers with these last. Both mutations induced a marked leftward shift in homomeric channel activation gating. Interestingly, the KCNT1 blockers quinidine (3-1000μM) and bepridil (0.03-10μM) inhibited both wild-type and mutant KCNT1 currents in a concentration-dependent manner, with mutant channels showing higher sensitivity to blockade. This latter result suggests two genotype-tailored pharmacological strategies to specifically counteract the dysfunction of KCNT1 activating mutations in MMPSI patients.
authors.affiliation: Laboratory of Molecular Medicine and Genomics, University of Salerno, Baronissi, (SA), Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Rizzo
authors.affiliation: Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ambrosino
authors.affiliation: Laboratory of Molecular Medicine and Genomics, University of Salerno, Baronissi, (SA), Italy; Genomix4Life Srl, Department of Medicine and Surgery, University of Salerno, Baronissi, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Guacci
authors.affiliation: Laboratory of Molecular Medicine and Genomics, University of Salerno, Baronissi, (SA), Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Chetta
authors.affiliation: Laboratory of Molecular Medicine and Genomics, University of Salerno, Baronissi, (SA), Italy; Genomix4Life Srl, Department of Medicine and Surgery, University of Salerno, Baronissi, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Marchese
authors.affiliation: Laboratory of Molecular Medicine and Genomics, University of Salerno, Baronissi, (SA), Italy; Genomix4Life Srl, Department of Medicine and Surgery, University of Salerno, Baronissi, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Rocco
authors.affiliation: Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy.
authors.forename: Maria Virginia
authors.initials: MV
authors.lastname: Soldovieri
authors.affiliation: Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Manocchio
authors.affiliation: Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Mosca
authors.affiliation: Child Neurology and Neurorehabilitation Unit, Department of Pediatrics, Regional Hospital of Bolzano, Bolzano, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Casara
authors.affiliation: Clinical Neurophysiology and Epilepsy Unit, Department of Child and Mother Health, University of Padua, Padua, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Vecchi
authors.affiliation: Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Taglialatela
authors.affiliation: Child and Adolescent Neuropsychiatry, Department of Medicine and Surgery, Salerno, Italy. Electronic address: gcoppola@unisa.it.
authors.forename: Giangennaro
authors.initials: G
authors.lastname: Coppola
authors.affiliation: Laboratory of Molecular Medicine and Genomics, University of Salerno, Baronissi, (SA), Italy; Molecular Pathology and Medical Genomics, "SS. Giovanni di Dio e Ruggi d'Aragona - Schola Medica Salernitana" Hospital of the University of Salerno, Salerno, Italy. Electronic address: aweisz@unisa.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Weisz
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D059472:Exome; D006801:Humans; D007223:Infant; D015640:Ion Channel Gating; D008297:Male; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D000081033:Potassium Channels, Sodium-Activated; D013036:Spasms, Infantile / Q000175:diagnosis / Q000235:genetics*
chemical_list: C585122:KCNT1 protein, human; D009419:Nerve Tissue Proteins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D000081033:Potassium Channels, Sodium-Activated
keywords: Early-onset epileptic encephalopathies; KCNT1 gene; MMPSI; Whole exome sequencing; Whole-cell electrophysiology