Transcranial magnetic stimulation, a mesoscale tool allowing exploration of a level of phenotype between genetic variation and its clinical consequence, is being applied in preliminary studies to help understand, at the system level, why different variants in SCN1A, for example, can sometimes lead to Dravet syndrome and at other times to milder forms of epilepsy. This evidence concerns the gene SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.