Both gain- and loss-of-function (GoF and LoF, respectively) variants in KCNA2 lead to cerebellar dysfunction, resulting in different neurological and -developmental disorders where the clinical picture is dominated by early-onset developmental and epileptic encephalopathy (DEE), ID, as well as ataxia and other movement disorders [40]. The gene discussed is KCNA2; the disease is developmental and epileptic encephalopathy.