SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: This mutation has previously been described in other individuals with Dravet Syndrome (SCN1A Infobase: http://www.scn1a.info/; SCN1A variant database: http://www.molgen.ua.ac.be/scn1amutations/) but the functional effects of the mutation are not known.