SCN2A and Its Related Epileptic Phenotypes

Andrea D. Praticò; Alessandro Giallongo; Marta Arrabito; Silvia D'Amico; Maria Cristina Gauci; Giulia Lombardo; Agata Polizzi; Raffaele Falsaperla; Martino Ruggieri

doi:10.1055/s-0041-1727097

Journal of Pediatric Neurology, Table of Contents

Journal of Pediatric Neurology 2023; 21(03): 173-185
DOI: 10.1055/s-0041-1727097

Review Article

SCN2A and Its Related Epileptic Phenotypes

Andrea D. Praticò

¹Unit of Rare Diseases of the Nervous System in Childhood, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy

,

Alessandro Giallongo

²Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy

,

Marta Arrabito

²Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy

,

Silvia D'Amico

²Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy

,

Maria Cristina Gauci

¹Unit of Rare Diseases of the Nervous System in Childhood, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy

,

Giulia Lombardo

²Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy

,

Agata Polizzi

³Chair of Pediatrics, Department of Educational Sciences, University of Catania, Catania, Italy

,

Raffaele Falsaperla

⁴Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy

⁵Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy

,

Martino Ruggieri

¹Unit of Rare Diseases of the Nervous System in Childhood, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy

› Author Affiliations

Abstract

Epilepsies due to SCN2A mutations can present with a broad range of phenotypes that are still not fully understood. Clinical characteristics of SNC2A-related epilepsy may vary from neonatal benign epilepsy to early-onset epileptic encephalopathy, including Ohtahara syndrome and West syndrome, and epileptic encephalopathies occurring at later ages (usually within the first 10 years of life). Some patient may present with intellectual disability and/or autism or movement disorders and without epilepsy. The heterogeneity of the phenotypes associated to such genetic mutations does not always allow the clinician to address his suspect on this gene. For this reason, diagnosis is usually made after a multiple gene panel examination through next generation sequencing (NGS) or after whole exome sequencing (WES) or whole genome sequencing (WGS). Subsequently, confirmation by Sanger sequencing can be obtained. Mutations in SCN2A are inherited as an autosomal dominant trait. Most individuals diagnosed with SCN2A–benign familial neonatal-infantile seizures (BFNIS) have an affected parent; however, hypothetically, a child may present SCN2A-BNFNIS as the result of a de novo pathogenic variant. Almost all individuals with SCN2A and severe epileptic encephalopathies have a de novo pathogenic variant. SNC2A-related epilepsies have not shown a clear genotype–phenotype correlation; in some cases, a same variant may lead to different presentations even within the same family and this could be due to other genetic factors or to environmental causes. There is no “standardized” treatment for SCN2A-related epilepsy, as it varies in relation to the clinical presentation and the phenotype of the patient, according to its own gene mutation. Treatment is based mainly on antiepileptic drugs, which include classic wide-spectrum drugs, such as valproic acid, levetiracetam, and lamotrigine. However, specific agents, which act directly modulating the sodium channels activity (phenytoin, carbamazepine, oxcarbamazepine, lamotrigine, and zonisamide), have shown positive result, as other sodium channel blockers (lidocaine and mexiletine) or even other drugs with different targets (phenobarbital).

Keywords

SCN2A - sodium channel - benign familial neonatal seizures - epileptic encephalopathy - autism

Full Text

References

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