SCN1A and epilepsy: Many epilepsy patients with hemizygous NaV1.1 loss of function display ataxia and motor delays and deficiencies (Claes et al., 2001; Fujiwara et al., 2003), which has traditionally been attributed to loss of NaV1.1 function in the brain, namely, the cerebellum (Kalume et al., 2007).