For example, the balance between Nav1.1 (haploinsufficiency leading to Dravet Syndrome) and Kv3.1 (dominant negative leading to PME and neurodevelopmental alterations) [76] is crucial in determining the fast-spiking nature of interneurons [77], with the loss of one of these components potentially severely altering the function of the other. Here, SCN1A is linked to encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.