Voltage-gated sodium channel α2-subunit gene related epilepsy with autism spectrum disorder: a case report / 中华神经科杂志

Objective:To summarize the clinical features and treatment of voltage-gated sodium channel α2-subunit (SCN2A) gene-related epilepsy.Methods:The clinical manifestion, video electroencephalography, head magnetic resonance imaging of a child diagnosed with epilepsy in Hebei Children′s Hospital were analyzed. Additionally, blood samples of the family were tested for the whole exome sequencing.Results:The boy aged 20 months,had been developed backward since childhood and accompanied by autism spectrum disorder manifestations. Seizures occurred at 19 months, manifested as isolated and clusters of spasms or generalized tonic seizures. The whole exome sequencing of the family revealed that the proband had c.4543C>T heterozygous mutation in the SCN2A gene, and both parents showed wild type. The effect of multiple anti-epileptic drugs on the children was not good, but the epilepsy was controlled after the final addition of perampane.Conclusions:The c.4543C>T heterozygous variant of SCN2A gene is the cause of disease in this child. This variant can cause epilepsy with autism spectrum disorder. The location and type of SCN2A mutations are strongly related with phenotypes, and a clear genetic etiology contributes to accurate treatment of children.

SCN2A mutation in an infant with Ohtahara syndrome and neuroimaging findings: expanding the phenotype of neuronal migration disorders

Neuronal migration disorders (NMDs) are a heterogeneous group of conditions caused by the abnormal migration of neuroblasts in the developing brain and nervous system, resulting in severe developmental impairment, intractable epilepsy and intellectual disability (Spalice et al. 2009). To date, many genes have been identified as the leading cause of migration defects, i.e. agyria/pachygyria, polymicrogyria, heterotopias, agenesis of the corpus callosum and agenesis of the cranial nerves (Spalice et al. 2009). Here, we present a patient with early infantile epileptic encephalopathy (Ohtahara syndrome) with seizure onset on the first dayof life, severe developmental delay and an abnormal brain MRI with excessive folding of small, fused gyri and bilateral perisylvian polymicrogyria, suggestive of neuronal migration disorder. To clarify the unknown aetiology, we conducted whole-exome sequencing, which detected a de novo missense variant (c.5308A>T; p.(Met1770Leu)) in the SCN2A gene. This is a report of SCN2A gene variant identified in a patient with neuronal migration disorder which could further expand the phenotypic spectrum of these genetic disorders.

Phenotype study of SCN2A gene related epilepsy / 中华儿科杂志

Objective@#To summarize the phenotype of epileptic children with SCN2A mutations.@*Methods@#Epileptic patients who were treated in the Pediatric Department of Peking University First Hospital from September 2006 to October 2017 and detected with SCN2A mutations by targeted next-generation sequencing were enrolled. Clinical manifestations of all patients were analyzed retrospectively.@*Results@#A total of 21 patients (16 boys and 5 girls) with SCN2A mutations were collected. Twenty-one SCN2A mutations were identified. Ten patients had mutations inherited from one of their parents and 11 patients had de novo mutations. The age of epilepsy onset was from 2 days to 2 years and 6 months: six patients with seizure onset in neonates (29%) , six patients with seizure onset between 1 month and 3 months of age (29%), three patients with seizure onset between 4 months and 6 months of age, two patients with seizure onset between 7 months and one year of age, and four patients with seizure onset beyond one year of age. Multiple seizure types were observed. The focal seizure was the most common seizure type which was observed in 18 patients (86%) . Spasm seizure was observed in 6 patients (29%) . Other seizure types were rare. In 19 patients, seizures manifested in clusters (90%) . In 3 patients, seizures manifested fever-sensitive. Nine of ten patients with inherited SCN2A mutations had normal development. However, all patients with de novo SCN2A mutations had mild or severer development delay. In 21 patients with SCN2A mutations, five were diagnosed with benign familial infantile epilepsy, 3 with benign familial neonatal-infantile epilepsy, 3 with Ohtahara syndrome, 3 with West syndrome, 2 with encephalopathy with early infantile onset epilepsy, one with febrile seizures plus, one with Dravet syndrome, one with encephalopathy with childhood-onset epilepsy, one with autism with epilepsy and one with intellectual disability with epilepsy.@*Conclusions@#The clinical features of patients with SCN2A mutations include that main seizure onset is the neonate and early infancy, and the main seizure type is the focal seizure, manifested in clusters. The large spectrum of SCN2A-related epilepsy, which not only includes epilepsy with a comparatively favorable prognosis, but also epileptic encephalopathy. De novo mutations often lead to severe phenotype with development delay.

Research progress on neurological diseases associated with SCN2A gene mutations / 中华实用儿科临床杂志

SCN2A gene encodes voltage-gated sodium channel protein Navl.2.Mutations of SCN2A gene lead to many neurological diseases,including benign epilepsy,epileptic encephalopathy and autism spectrum disorders (ASD).Most mutations of SCN2A are missense mutation,mild epilepsy might be associated with missense mutations inherited from a single parent,many nonsense and missense mutations identified in severe cases are de novo and truncated mutation.There is no absolute relationship between genotype and phenotype.Functional changes and severity of the phenotype might preliminary predict according to SCN2A mutation regions of the protein.Sodium channel blockers are good choice as first-line treatment for those early onset encephalopathy patients,but also should be individualized.

Study of Pathogenic gene spectrum in benign familial infantile epilepsy / 中华实用儿科临床杂志

Objective To investigate the gene mutations in benign familial infantile epilepsy(BFIE)in Chi-na. Methods Data of all BFIE probands and their family members were collected from Peking University First Hospital and other three hospitals between October 2006 and June 2017. Clinical phenotypes of affected members were analyzed. Genomic DNA was extracted from peripheral blood samples with standard protocol. Mutations in PRRT2 were screened using Sanger sequencing. For families that PRRT2 mutations were not detected by Sanger sequencing,candidate gene mutations were further screened by next - generation sequencing. Results A total of 71 families including 227 affected members were collected. Genetic testing led to the identification of gene mutations in 52 families (52 / 71,73. 2％). Forty - three families had PRRT2 mutations (43 / 71,60. 6％),including 40 families with frameshift mutations(hotspot mutations c. 649_650insC and c. 649delC were detected in 29 families and 6 families,respectively),one family with nonsense mutation,one family with a loss of a stop codon,and one family with a microdeletion of the gene. C. 560_561insT and c. 679C > T were novel PRRT2 mutations. Five families had SCN2A mutations. All SCN2A mutations were missense mutations(c. 668G > A,c. 752T > C,c. 1307T > C,c. 4835C > G,c. 1737C > G). Mutation c. 752T > C, c. 1307T > C,c. 4835C > G,and c. 1737C > G were novel mutations. Three families had KCNQ2 mutations. All KCNQ2 mutations were missense mutations(c. 775G > A,c. 237T > G,c. 1510C > T). Mutation c. 237T > G and c. 1510C > T were novel mutations. One family had a novel GABRA6 mutation c. 523G > T. In 71 BFIE families,16 families had mem-bers who showed paroxysmal kinesigenic dyskinesias(PKD)and subclassified as infantile convulsions with paroxysmal choreoathetosis syndrome(ICCA). Fifteen ICCA families were found having PRRT2 mutations (15 / 16,93. 8％). The remaining ICCA family was not detected with any pathogenic mutation. Conclusion There is high frequency of gene mutations in BFIE families. Mutations in KCNQ2,SCN2A,and PRRT2 are genetic causes of BFIE. PRRT2 is the main gene responsible for BFIE. GABRA6 mutation might be a new cause of BFIE.