Phenotypic and genetic spectrum of SCN8A-related disorders, treatment options, and outcomes.
Adolescent
Adult
Brain Diseases
/ genetics
Child
Child, Preschool
Death, Sudden
/ etiology
Electroencephalography
/ methods
Epilepsy
/ diagnosis
Female
Humans
Infant
Intellectual Disability
/ genetics
Male
Mutation
/ genetics
NAV1.6 Voltage-Gated Sodium Channel
/ genetics
Seizures
/ genetics
Young Adult
SCN8A
autism
epilepsy
intellectual disability
movement disorders
voltage-gated sodium channels
Journal
Epilepsia
ISSN: 1528-1167
Titre abrégé: Epilepsia
Pays: United States
ID NLM: 2983306R
Informations de publication
Date de publication:
12 2019
12 2019
Historique:
received:
07
02
2019
accepted:
29
07
2019
entrez:
7
1
2020
pubmed:
7
1
2020
medline:
24
4
2020
Statut:
ppublish
Résumé
Pathogenic variants in SCN8A have originally been described in patients with developmental and epileptic encephalopathy (DEE). However, recent studies have shown that SCN8A variants can be associated with a broader phenotypic spectrum, including the following: (1) Patients with early onset, severe DEE, developing severe cognitive and motor regression, pyramidal/extrapyramidal signs, and cortical blindness. Severe SCN8A-DEE is characterized by intractable seizures beginning in the first months of life. The seizures are often prolonged focal hypomotor and occur in clusters, with prominent vegetative symptoms (apnea, cyanosis, mydriasis), evolving to clonic or bilateral tonic-clonic manifestations. Spasm-like episodes, cortical myoclonus, and recurrent episodes of status epilepticus are also common. Electroencephalograms (EEGs) show progressive background deterioration and multifocal abnormalities, predominant in the posterior regions. (2) Sporadic and familial patients with mild-to-moderate intellectual disability, discrete neurological signs, and treatable epilepsy. EEG is abnormal in half of the cases, showing multifocal or diffuse epileptiform abnormalities. (3) Familial cases with benign infantile seizures, sometimes associated with paroxysmal dyskinesia later in life, with no other neurological deficits, normal cognition, and usually normal interictal EEG. (4) Patients without epilepsy but with cognitive and/or behavioral disturbances, or with movement disorders. Extrapyramidal features, such as dyskinesia, ataxia, and choreoathetosis are common in all groups. Early death has been reported in about 5% of the patients, most often in the subgroup of severe DEE. Premature death occurs during early childhood and often for causes other than sudden unexpected death in epilepsy. All epilepsy subgroups exhibit better seizure control with sodium channel blockers, usually at supratherapeutic doses in the severe cases. In severe SCN8A-DEE, ketogenic diet often has a good effect, whereas levetiracetam has a negative effect, if any. The familial SCN8A-related epilepsies show an autosomal dominant pattern of inheritance, whereas the vast majority of SCN8A-DEEs occur de novo.
Substances chimiques
NAV1.6 Voltage-Gated Sodium Channel
0
SCN8A protein, human
0
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
S77-S85Informations de copyright
Wiley Periodicals, Inc. © 2019 International League Against Epilepsy.
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