Rare dysfunctional SCN2A variants are associated with malformation of cortical development.
Susan Sotardi, Roy Ben-Shalom, Ala Somarowthu, Mia Sherer, Angeliki Vakrinou, Laura Malerba, Brunetta Guaragni, Natalie Ginn, D Isum Ward, Jinan Jiang, Ethan M Goldberg, Jérôme Clatot, Renzo Guerrini, Sanjay M Sisodiya, Nicola Specchio, Marina Trivisano, Alfred L George, Christopher H Thompson, Ingo Helbig, Simona Balestrini
Journal: Epilepsia
2025;66(3):914-928
PMID: 39707911
Abstract
OBJECTIVE
SCN2A encodes the voltage-gated sodium (Na+) channel α subunit Na1.2, which is important for the generation and forward and back propagation of action potentials in neurons. Genetic variants in SCN2A are associated with a spectrum of neurodevelopmental disorders. However, the mechanisms whereby variation in SCN2A leads to disease remains incompletely understood, and the full spectrum of SCN2A-related disorders may not be fully delineated.
METHODS
Here, we identified seven de novo heterozygous variants in SCN2A in eight individuals with developmental and epileptic encephalopathy (DEE) accompanied by prominent malformation of cortical development (MCD). We characterized the electrophysiological properties of Na + currents in human embryonic kidney (HEK) cells transfected with the adult (A) or neonatal (N) isoform of wild-type (WT) and variant Na1.2 using manual and automated whole-cell voltage clamp recording.
RESULTS
The neonatal isoforms of all SCN2A variants studied exhibit gain of function (GoF) with a large depolarized shift in steady-state inactivation, creating a markedly enhanced window current common across all four variants tested. Computational modeling demonstrated that expression of the Na1.2-p.Met1770Leu-N variant in a developing neocortical pyramidal neuron results in hyperexcitability.
SIGNIFICANCE
These results support expansion of the clinical spectrum of SCN2A-related disorders and the association of genetic variation in SCN2A with MCD, which suggests previously undescribed roles for SCN2A in fetal brain development.
© 2024 The Author(s). Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.
Address:
Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.; Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; The University of California, Berkeley, California, USA.; Child Neurology, Epilepsy and Movement Disorders, Bambino Gesù, IRCCS Children's Hospital, Rome, Italy.; Department of Neuroscience and Medical Genetics, Meyer Children's Hospital IRCCS, Florence, Italy.; University of Florence, Florence, Italy.; Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, South Dakota, USA.; Neonatology and Neonatal Intensive Care Unit, Children's Hospital, ASST-Spedali Civili of Brescia, Brescia, Italy.; Unit of Child Neurology and Psychiatry, ASST-Spedali Civili of Brescia, Brescia, Italy.; Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK.; Department of Neurology, The University of California, Sacramento, California, USA.; Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.; Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Pennsylvania, USA.; Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.; Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.; Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Pennsylvania, USA.; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
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MeSH Terms:
Humans,
NAV1.2 Voltage-Gated Sodium Channel,
Female,
HEK293 Cells,
Male,
Malformations of Cortical Development,
Child,
Child, Preschool,
Adult,
Adolescent,
Infant,
Patch-Clamp Techniques,
Genetic Variation