SCN2A encephalopathy: A major cause of epilepsy of infancy with migrating focal seizures.
OBJECTIVE
De novo SCN2A mutations have recently been associated with severe infantile-onset epilepsies. Herein, we define the phenotypic spectrum of SCN2A encephalopathy.


METHODS
Twelve patients with an SCN2A epileptic encephalopathy underwent electroclinical phenotyping.


RESULTS
Patients were aged 0.7 to 22 years; 3 were deceased. Seizures commenced on day 1-4 in 8, week 2-6 in 2, and after 1 year in 2. Characteristic features included clusters of brief focal seizures with multiple hourly (9 patients), multiple daily (2), or multiple weekly (1) seizures, peaking at maximal frequency within 3 months of onset. Multifocal interictal epileptiform discharges were seen in all. Three of 12 patients had infantile spasms. The epileptic syndrome at presentation was epilepsy of infancy with migrating focal seizures (EIMFS) in 7 and Ohtahara syndrome in 2. Nine patients had improved seizure control with sodium channel blockers including supratherapeutic or high therapeutic phenytoin levels in 5. Eight had severe to profound developmental impairment. Other features included movement disorders (10), axial hypotonia (11) with intermittent or persistent appendicular spasticity, early handedness, and severe gastrointestinal symptoms. Mutations arose de novo in 11 patients; paternal DNA was unavailable in one.


CONCLUSIONS
Review of our 12 and 34 other reported cases of SCN2A encephalopathy suggests 3 phenotypes: neonatal-infantile-onset groups with severe and intermediate outcomes, and a childhood-onset group. Here, we show that SCN2A is the second most common cause of EIMFS and, importantly, does not always have a poor developmental outcome. Sodium channel blockers, particularly phenytoin, may improve seizure control.
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Katherine B
KB
Howell
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Jacinta M
JM
McMahon
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Gemma L
GL
Carvill
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Dimira
D
Tambunan
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Mark T
MT
Mackay
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Victoria
V
Rodriguez-Casero
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Richard
R
Webster
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Damian
D
Clark
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Jeremy L
JL
Freeman
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Sophie
S
Calvert
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Heather E
HE
Olson
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Simone
S
Mandelstam
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Annapurna
A
Poduri
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
Heather C
HC
Mefford
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia.
A Simon
AS
Harvey
From the Departments of Neurology (K.B.H., M.T.M., V.R.-C., J.L.F., A.S.H., I.E.S.) and Radiology (S.M.), The Royal Children's Hospital, Melbourne; Department of Paediatrics (K.B.H., M.T.M., S.M., A.S.H., I.E.S.), The University of Melbourne; Murdoch Childrens Research Institute (K.B.H., M.T.M., J.L.F., A.S.H.), Melbourne; Epilepsy Research Centre (J.M.M., I.E.S.), Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia; Division of Genetic Medicine (G.L.C., H.C.M.), Department of Paediatrics, University of Washington, Seattle; Epilepsy Genetics Program (D.T., H.E.O., A.P.), Department of Neurology, Harvard Medical School, Boston Children's Hospital, MA; TY Nelson Department of Neurology and Neurosurgery (R.W.), The Children's Hospital at Westmead, Sydney; Department of Neurology (D.C.), Women's and Children's Hospital, Adelaide; Neurosciences Children's Health Queensland (S.C.), Lady Cilento Children's Hospital, Brisbane; and Florey Institute of Neuroscience and Mental Health (S.M., A.S.H., I.E.S.), Melbourne, Australia. scheffer@unimelb.edu.au.
Ingrid E
IE
Scheffer
D000293:Adolescent; D001927:Brain Diseases / Q000150:complications / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods; D004828:Epilepsies, Partial / Q000150:complications / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation / Q000235:genetics*; D062551:NAV1.2 Voltage-Gated Sodium Channel / Q000235:genetics*; D010641:Phenotype; D012640:Seizures / Q000150:complications / Q000235:genetics*; D013036:Spasms, Infantile / Q000235:genetics; D055815:Young Adult
D062551:NAV1.2 Voltage-Gated Sodium Channel; C568251:SCN2A protein, human