Assessment of Safety of the Use of Fenfluramine in Children With Dravet Syndrome Under 24 Months of Age

Inclusion Criteria: Treating physicians must submit a clinical statement of potential benefit to the lead site for review of the multi-PIs, which includes patient's gender, age, diagnosis, genetic pathogenic variant, co-morbidities, seizure history, prior and current therapies, response to prior therapies and reason for request. Echocardiogram (ECHO) results must also be submitted to the lead site prior to final approval. Patients must be between 12 and 23 months old to be eligible. Each subject will be reviewed by the multi-PIs to ensure agreement that the subject has Dravet syndrome. Additional inclusion criteria: 1. SCN1A with a known or presumed pathogenic variant or VUS with a history of prolonged seizure or a clinical diagnosis of Dravet syndrome. 2. Failure of at least one anti-seizure medication that is not a sodium channel blocker (lamotrigine, oxcarbazepine, carbamazepine, eslicarbazepine) Exclusion Criteria: 1. Patients with mild or greater mitral valve regurgitation and/or trace or greater aortic valve regurgitation will not be eligible for participation. The clinical statement can be submitted first for initial, conditional approval and then ECHO results can be submitted at a later date for final approval. 2. Patients with failure to thrive will not be eligible for participation as fenfluramine can suppress appetite and has a risk for weight loss. Failure to thrive will be evaluated on the following criteria: 1. Weight less than the 2nd percentile. 2. Lack of weight gain that crosses two or more of the major percentile lines and is not congruent with length. Inclusion of patients will be at the sole discretion of the multi-PIs based on a majority vote.