Developmental and epileptic encephalopathy (DEE) is a severe neurodevelopmental disorder in which abnormal manifestations result from a combination of underlying developmental abnormalities and frequent epileptic activity.[1] Pathogenic variants in ion channel genes are common causes of DEE[2]; approximately 25% of monogenic inherited epilepsy cases are associated with ion channel variants.[3] Potassium channels represent the most numerous and complex family of ion channels. Here, KCNA3 is linked to developmental and epileptic encephalopathy.