Human mutations of KCNT1, the gene coding for the Na+-activated K+ channel Slack (Sequence Like a Ca2+-activated K+ Channel, KNa2.1, Slo2.2) cause at least two childhood epilepsy syndromes called malignant migrating focal seizures of infancy (MMFSI) and autosomal-dominant nocturnal frontal lobe epilepsy (ADNFLE) [3] associated with severe ID [4–6]. The gene discussed is KCNT1; the disease is autosomal dominant nocturnal frontal lobe epilepsy.