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). The gene discussed is SCN1A; the disease is Dravet syndrome.