The SCN8A gene defect is a rare genetic disorder caused by mutations in the SCN8A gene. This gene codes for a voltage-gated sodium channel (Nav1.6), which is important for electrical signal transmission in the brain.

Changes in the SCN8A gene can lead to epilepsy with difficult-to-treat seizures, which usually begin in early childhood. Many children also show developmental delay, impaired motor skills, muscle hypotonia or spasticity and sometimes cognitive impairment.

The course of the disease varies greatly: some children have a rather mild form, others are severely affected and require extensive therapeutic support.