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Conti V, Aracri P, Chiti L, Brusco S, Mari F, Marini C, Albanese M, Marchi A, Liguori C, Placidi F, Romigi A, Becchetti A, Guerrini R. Nocturnal frontal lobe epilepsy with paroxysmal arousals due to CHRNA2 loss of function. Neurology 2015; 84:1520-8. [PMID: 25770198 DOI: 10.1212/wnl.0000000000001471] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/29/2014] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE We assessed the mutation frequency in nicotinic acetylcholine receptor (nAChR) subunits CHRNA4, CHRNB2, and CHRNA2 in a cohort including autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) and sporadic nocturnal frontal lobe epilepsy (NFLE). Upon finding a novel mutation in CHRNA2 in a large family, we tested in vitro its functional effects. METHODS We sequenced all the coding exons and their flanking intronic regions in 150 probands (73 NFLE, 77 ADNFLE), in most of whom diagnosis had been validated by EEG recording of seizures. Upon finding a missense mutation in CHRNA2, we measured whole-cell currents in human embryonic kidney cells in both wild-type and mutant α2β4 and α2β2 nAChR subtypes stimulated with nicotine. RESULTS We found a c.889A>T (p.Ile297Phe) mutation in the proband (≈0.6% of the whole cohort) of a large ADNFLE family (1.2% of familial cases) and confirmed its segregation in all 6 living affected individuals. Video-EEG studies demonstrated sleep-related paroxysmal epileptic arousals in all mutation carriers. Oxcarbazepine treatment was effective in all. Whole-cell current density was reduced to about 40% in heterozygosity and to 0% in homozygosity, with minor effects on channel permeability and sensitivity to nicotine. CONCLUSION ADNFLE had previously been associated with CHRNA2 dysfunction in one family, in which a gain of function mutation was demonstrated. We confirm the causative role of CHRNA2 mutations in ADNFLE and demonstrate that also loss of function of α2 nAChRs may have pathogenic effects. CHRNA2 mutations are a rare cause of ADNFLE but this gene should be included in mutation screening.
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Affiliation(s)
- Valerio Conti
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Patrizia Aracri
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Laura Chiti
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Simone Brusco
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Francesco Mari
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Carla Marini
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Maria Albanese
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Angela Marchi
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Claudio Liguori
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Fabio Placidi
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Andrea Romigi
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Andrea Becchetti
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Renzo Guerrini
- From the Pediatric Neurology and Neurogenetics Unit and Laboratories (V.C., L.C., F.M., C.M., R.G.), A. Meyer Children's Hospital-University of Florence; Department of Biotechnology and Biosciences and Center of Neuroscience (P.A., S.B., A.B.), Università di Milano-Bicocca, Milan; Neurophysiopathology Unit (M.A., A.M., C.L., F.P., A.R.), Sleep and Epilepsy Center, Department of Systems Medicine, University of Rome Tor Vergata General Hospital, Rome; IRCCS Neuromed (A.R.), Pozzilli, Isernia; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy.
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