We crossed VGAT-ChR2 mice with knock-out Scn1a+/– mice, which model the epileptic encephalopathy Dravet syndrome and in which one allele of the Scn1a gene is not functional, causing NaV1.1 haploinsufficiency and hypoexcitability of GABAergic neurons (17, 21). Here, SCN1A is linked to encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.