Homozygous SCN1B Mutation Presenting as Early-Onset Developmental and Epileptic Encephalopathy and Not Dravet Syndrome: A Case Report
Abstract number :
3.436
Submission category :
18. Case Studies
Year :
2018
Submission ID :
502647
Source :
www.aesnet.org
Presentation date :
12/3/2018 1:55:12 PM
Published date :
Nov 5, 2018, 18:00 PM
Authors :
Claudine Sculier, ULB-Hôpital Erasme; Damien Lederer, Institute of Pathology and Genetics; Sandrine Mary, Institute of Pathology and Genetics (IPG), Charleroi; Berten Ceulemans, Universitair Ziekenhuis Antwerpen; Patrick Van Bogaert, CHU Angers, Univ
Rationale: Heterozygous mutations in the SCN1B gene have been reported in patients with generalized epilepsy with febrile seizures plus (GEFS+). Homozygous SCN1B mutations have been reported in two patients with electroclinical features suggestive of Dravet syndrome (DS). Nevertheless, no SCN1B mutation were found in a study of DS patients SCN1A -/- and a review of the phenotypic features of the homozygous SCN1B patient reported by Patino suggested that he presented early-onset developmental and epileptic encephalopathy and not DS. Methods: The aim of this case report is to describe the electroclinical features of the third reported case of homozygous SCN1B mutation. Results: This girl was born after a normal pregnancy, from consanguineous parents with a familial pedigree highly suggestive of GEFS+. Hypotonia was noticed from birth and at 2.5months of age, she started to present frequent multifocal myoclonias often associated with fever. EEG presented a normal background, with frequent rolandic left or right positive discharges of spikes, associated with heterolateral myoclonias. At 3 months old, she presented a myoclonic status epilepticus during an episode of fever and several episodes of focal seizures with secondary generalization. BERA showed evidence for a bilateral hearing loss with evoked otoacoustic emissions preserved. A gene panel testing by DNA amplified by multiplex PCR (Ampliseq®) and re-sequenced by next generation sequencing on Ion PGM® showed that this patient presented a homozygous SCN1B mutation (c.253C>T ; p.Arg85Cys) and both parents were found to be heterozygous carriers. At the age of 36 months, EEG has not changed since the beginning of epilepsy, myoclonias and focal seizures are refractory to medical treatment and the child has virtually no development. Nevertheless, no episodes of status epileptics have occurred since the add-on of fenfluramine to ketogenic diet, valproate, topiramate and clonazepam. Conclusions: In this case report, we confirm that the electroclinical presentation of homozygous SCN1B mutation is more compatible with early-onset developmental and epileptic encephalopathy than DS. Funding: No funding