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. Author manuscript; available in PMC: 2019 Jul 1.
Published in final edited form as: Ann Neurol. 2018 Jul;84(1):1–9. doi: 10.1002/ana.25268

Table 1.

Comparisons of Functional Effect, Clinical Phenotype and Variant Type in SCN1A, SCN2A and SCN8A Channelopathies

PHENOTYPE
Variant type Effect on
Channel
Function		 EOEE B(F) NIS
(SCN2A/8A)
or
GEFS +
(SCN1A)		 Epilepsy
(other)		 Other;
No epilepsy		 Number
of
variants
SCN2A/8A
Missense Gain, loss or mixed: dependent on location 65 % (n=113) 15 % (n=26) 12 % (n=22) 8 % (n=14) 175
Nonsense/frameshift/splice site Complete loss 0 0 33 % (n=15) 67% (n=30) 45
SCN1A
Missense Gain, loss or mixed: dependent on location 83 % (n=434) 9 % (46) 6 % (n=34) 2 % (n=9) 523
Nonsense/frameshift/splice site Complete loss 93 % (n=476) 1 % (n=7) 6 % (n=28) 0 511

Abbreviations: EOEE = early onset epileptic encephalopathy as associated syndromes; B(F)NIS = Benign (familial) neonatal/infantile seizures; GEFS+ = Genetic Epilepsy with Febrile Seizures Plus; Other; No epilepsy, includes developmental delay, schizophrenia, autism spectrum disorders, ataxia and familial hemiplegic migraine with no history of seizures.