Description:
<jats:title>Summary</jats:title><jats:p>Most patients with Dravet syndrome have de novo mutations in the neuronal voltage‐gated sodium channel type 1 (<jats:italic>SCN1A</jats:italic>) gene. We report on two unrelated fathers with severe childhood epilepsy compatible with a possible diagnosis of Dravet syndrome, who both have a child with Dravet syndrome. Analysis of the SCN1A gene revealed a pathogenic mutation in both children. One father exhibited somatic mosaicism for the mutation detected in his son. A relatively favorable cognitive outcome in patients with Dravet syndrome patients may be explained by somatic mosaicism for the <jats:italic>SCN1A</jats:italic> mutation in brain tissue. A mild form of Dravet syndrome in adult patients is associated with a high recurrence risk and possibly a more severe epilepsy phenotype in their offspring.</jats:p>