For example, Berecki et al. [31] suggested that a variant in NaV1.1 (T226M) that is associated with a more severe phenotype than Dravet syndrome [32] leads to a reduction of NaV1.1 current through both the mutant and the wildtype allele so that the sum current is >0 but <50%. The gene discussed is SCN1A; the disease is encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.