Neonatal SCN2A encephalopathy: A peculiar recognizable electroclinical sequence.

Area of Science:

• Genetics
• Neurology
• Epileptology

Background:

• Gain-of-function mutations in the Sodium voltage-gated channel alpha subunit 2 (SCN2A) gene are increasingly identified as a cause of epileptic encephalopathy.
• SCN2A encodes the Nav1.2 subunit crucial for voltage-gated sodium channel function in pyramidal neurons.

Observation:

• Three new cases of de novo SCN2A mutations presented with neonatal-onset seizures characterized by apnea, cyanosis, and alternating partial motor seizures.
• Seizures evolved to generalized tonic-clonic seizures and epileptic spasms by three months, accompanied by a discontinuous EEG pattern.
• Seizure frequency spontaneously decreased within the first year of life, with two patients showing improvement with sodium channel blockers.

Findings:

• The observed phenotype differs from Ohtahara syndrome and malignant migrating partial seizures in infancy (EMPSI).
• A distinct electroclinical sequence, including alternating partial motor seizures, evolving spasms, and a discontinuous EEG pattern, suggests SCN2A mutations.
• Early administration of sodium channel blockers may be beneficial.

Implications:

• Recognizing this specific SCN2A encephalopathy phenotype can lead to earlier diagnosis and targeted treatment.
• This finding highlights the importance of genetic testing for SCN2A in infants with specific seizure patterns and EEG findings.
• Further research into the therapeutic efficacy of sodium channel blockers in SCN2A-related epilepsies is warranted.