There are reports of mutation in PCDH19, a gene that encodes a calcium-dependent cell-adhesion protein and is located on chromosome X, in female patients with clinical symptoms related to Dravet syndrome.55,56 Interestingly, 11-12% of affected patients, who did not show any mutation in the mentioned genes, had pathogenic copy number variations (CNVs) in SCN1A gene. This evidence concerns the gene SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.