SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Despite there being >1,200 different reported SCN1A mutations, only 18% of mutations are recurrent.4 Mutations associated with GEFS+ are more likely to have a lower Grantham score than those that cause Dravet phenotypes.4,14 Missense mutations in the pore region lead to complete loss of function, similar to haploinsufficiency, but are seen in both Dravet syndrome (54%) and GEFS+ (31%).4 It is therefore not usually possible to predict an individual's phenotype on the basis of their specific SCN1A mutation.