Another clear application of a PM-based approach is the avoidance of those drugs which may cause worsening of seizures by exasperating the underlying molecular defect, i.e., sodium channel blockers must be avoided in patients with Dravet syndrome (DS) carrying loss-of-function mutations in the sodium voltage-gated channel alpha subunit 1 (SCN1A). This evidence concerns the gene SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.