It was approved for use in the treatment of seizures associated with SCN1A Dravet syndrome (and subsequently for Lennox-Gastaut Syndrome) in patients 2 years of age and older with a warning of valvular heart disease and pulmonary hypertension. The gene discussed is SCN1A; the disease is encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.