Phenotypic spectrum,treatment and prognosis of 80 cases of epilepsy associated with SCN8A variantion

LI Yuan; LIU Wen-wei; CHENG Miao-miao; WANG Ting; OUYANG Shi-jia; LIU Chang-hao; TAN Quan-zhen; YANG Ying; YANG Xiao-ling; ZHANG Yue-hua

doi:10.19538/j.ek2025070610

Abstract：Objective The aim of this study was to summarize the phenotypic spectrum,treatment and prognosis of epilepsy caused by SCN8A variants.Methods The features of clinical phenotypes and genotypes of epilepsy children with SCN8A variants detected by next-generation sequencing were analyzed.The treatment and prognosis of all patients were followed up.Results Totally 80 epilepsy children with heterozygous SCN8A variants were collected,including 39 males,and 41 females.56 different variation types were identified,including 52 missense variants(one patient with mosaic variant),3 splicing site variants,and 1 insertion variant.76 patients had de novo variants,4 patients had inherited variants.22 variants were not reported previously.The seizure onset age ranged from the first day of life to 6 years and 4 months(Medium:4 months).There are various types of epileptic seizures.The common seizure types included focal seizures(76.2％,61/80),generalized tonic-clonic seizures(26.2％,21/80),and epileptic spasms(20.0％,16/80).81.2％(65/80)of patients had developmental delay.Two patients comorbid with autism spectrum disorder.The EEG exhibited slow background activity(30.0％,24/80).Interictal EEG showed multifocal discharges(21.3％,17/80),generalized discharges(20.0％,16/80),focal discharges(5％,4/80),and hypsarrhythmia(6.3％,5/80).Electrical status epilepticus in slow wave sleep(ESES)was monitored in one patient.Seizures were captured in 35 patients.Brain MRI was abnormal in some patients(57.5％,46/80),including enlargement of subarachnoid spaces in the frontal and temporal region,enlargement of bilateral lateral ventricle,delayed myelination of white matter,agenesis of corpus callosum,and brain atrophy.Totally 13 patients were diagnosed with infantile epileptic spasms syndrome,52 patients with unclassified developmental and epileptic encephalopathy(DEE),15 patients with self-limited(familial)infantile epilepsy(SeLIE).The last follow-up age was ranged from 7 months to 14 year and 6 months(medium:5 year and 11 moths).21(26.2％)patients were seizure free.Two patients were died.57 patients still had seizures at last followed up.Conclusion The variants of most SCN8A-related epilepsy patients were missense variants.The onset of seizure starts during infancy,with focal seizures being the most common seizure types.The phenotypic spectrum varies widely,ranging from mild SeLIE to severe DEE.The efficacy of sodium channel blocker is better than other anti-seizure drugs,but most patients are with refractory epilepsy.