Microduplication of SCN2A Gene in a Child with Drug-Resistant Epilepsy and Developmental/Epileptic Encephalopathy with Spike Wave Activation During Sleep.

Duplications in chromosomal locus 2q24.3 region that solely involve SCN2A remain less explored. Favorable outcomes have been reported in patients with SCN2A gene duplications in cases of mild epilepsy with onset during the neonatal to infantile period, or in infantile epileptic spasm syndrome. Herein, we report a case of microduplications, including SCN2A gene duplications, wherein developmental/epileptic encephalopathy with spike-wave activation during sleep (D/EE-SWAS) developed. A 3-day-old girl without birth complications exhibited tonic seizures in her right limb with eye deviation to the right. She developed drug-resistant seizures, including atypical absence seizures, at 1 year and 6 months old. Despite achieving seizure freedom at 9 years old, she experienced academic difficulties. D/EE-SWAS was diagnosed based on the long-term electroencephalogram findings. Following a corpus callosotomy at 11 years old, her academic performance and emotional expression improved. Comprehensive genetic analysis at 10 years old revealed a microduplication spanning approximately 300 kb within the 2q24.3 region, which included a segment of the SCN2A gene and an adjacent CSRNP3 gene. In conclusion, we reported a rare case of duplications solely encompassing SCN2A. Corpus callosotomy resolved the D/EE-SWAS.