METHODS: 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.
RESULTS: 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.
CONCLUSIONS: This report expands our knowledge of the genetic basis of migrating focal seizures of infancy to include mutations in SCN2A gene.