Table 2.

SCN8A-Related Epilepsy and/or Neurodevelopmental Disorders: Comparison of Phenotypes by Select Features

FeatureSCN8A-Related Phenotype
DEEMild-to-moderate DEESeLFIENDDwGENDDwoE
Seizure types Focal, multifocal, bilateral tonic-clonic, tonic, or infantile spasmsFocal, multifocal, bilateral tonic-clonic, or tonicFocal, multifocal, bilateral tonic-clonic; may be self-limitingAbsence, bilateral tonic-clonic, or febrileNA
% w/epilepsy 100%100%100%100%0%
Median age of epilepsy onset ~3 months~5 months~6 months~42 monthsNA
Motor development Delayed, often nonambulatoryDelayedNormalDelayedDelayed
Speech development Delayed, often nonverbalDelayedNormal to mildly delayedDelayedDelayed
Cognition Moderate-to-severe IDMild-to-moderate IDNormal to mildly delayedNormal to severe ID (usually mild to moderate)Normal to severe ID
Other Hypotonia, CVI, ataxia, GI symptomsBehavioral issues, ataxiaParoxysmal kinesigenic dyskinesiaBehavioral issues, ADHD, ASDASD
Most common SCN8A variant type 1 GoFGoFGoFLoFLoF

ADHD = attention-deficit/hyperactivity disorder; ASD = autism spectrum disorder; CVI = cortical visual impairment; DEE = developmental and epileptic encephalopathy; GI = gastrointestinal; GoF = gain of function; ID = intellectual disability; LoF = loss of function; NA = not applicable; NDDwGE = neurodevelopmental disorder with generalized epilepsy; NDDwoE = neurodevelopmental disorder without epilepsy; SeLFIE = self-limited familial infantile epilepsy

1.

From: SCN8A-Related Epilepsy and/or Neurodevelopmental Disorders

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