From:  First report of SCN8A-related neurodevelopmental disorder and a case of SCN1A-related Dravet syndrome in Libya

 Clinical and genetic characteristics of the patients.

FeaturePatient 1Patient 2Patient 3
Age at onsetOne weekOne weekNine months
Age at genetic testing34 years31 years10 years
SexFemaleFemaleMale
Family historySister affectedSibling of patient 1Negative
ConsanguinityYesYesYes
Birth historyUneventfulUneventfulUneventful
Developmental milestonesDelayedDelayedDelayed
Intellectual functionNormalMildly impairedSeverely impaired
SeizureNoNoYes (intractable)
Anti-seizure medicationNoNoValproate and levetiracetam
Major neurological featuresSpastic paraparesis, contractures, kyphoscoliosisSpastic quadriplegia, athetosis, orofacial dyskinesia, kyphoscoliosisDystonia, autism, global delay
MRI headNormalNormalNormal
Laboratory testsNormalNormalNormal
EEGNot performedNot performedGeneralized spike and wave
GeneSCN8A (NM_014191.4)SCN8A (NM_014191.4)SCN1A (NM_001165963.3)
Associated disorderSCN8A-related neurodevelopmental disorderSCN8A-related neurodevelopmental disorderDravet syndrome
Variant*c.142G>A
p.Asp48Asn
Chr12:52056743
c.142G>A
p.Asp48Asn
Chr12:52056743
c.2113del
p.Glu705Lysfs*10
Chr2:166898864
ZygosityHeterozygousHeterozygousHeterozygous
ACMG classificationVUSVUSLikely pathogenic

ACMG: American College of Medical Genetics and Genomics; VUS: variant of uncertain significance; EEG: electroencephalogram. * All genomic coordinates are based on the GRCh37/hg19 human genome build.