SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: The differences in the MRI scans of SCN1A and PCDH19 mutations have been documented in Dravet syndrome with initial normal brain MRI scans that eventually progressed to cortical or cerebellar atrophy, cortical dysplasia, and temporal lobe abnormalities at 2–3 years.