Novel de novo SCN2A Mutation in a Child With Migrating Focal Seizures of Infancy

BACKGROUND: Migrating focal seizures of infancy are characterized by seizure onset within 7 months of age, migrating focal motor seizures with multifocal ictal electroencephalography discharges intractable to conventional antiepileptic drugs, and poor prognosis. Reported genetic etiologies include SCN1A and KCNT1 mutations and homozygous deletion of the PLCB1 gene. Here we report a novel SCN2A mutation in a child with this syndrome. PATIENT:A 7-week-old girl was admitted to our hospital for management of status epilepticus. She was the product of a full-term unremarkable pregnancy. Seizures started around 5 weeks of age and remained medically refractory. Electroencephalography showed multifocal epileptiform discharges as well as seizures arising from multifocal regions in both cerebral hemispheres. Based on her phenotype, a diagnosis of migrating focal seizures of infancy was made. RESULT: A novel de novo missense mutation was identified in the SCN2A gene, exon 22 (coding for voltage-gated sodium channel type II): c.3977T>A (p.V1326D). This mutation affects a highly evolutionarily conserved area of the gene and replaces hydrophobic nonpolar valine with polar aspartic acid; thus, it is predicted to affect protein function and is presumed pathogenic. DISCUSSION: This report expands our knowledge of the genetic basis of migrating focal seizures of infancy to include mutations in SCN2A gene.