Heterozygous inherited mutations in their principle subunits K<sub>v</sub> 7.2/KCNQ2 and K<sub>v</sub> 7.3/KCNQ3 cause benign familial neonatal epilepsy whereas patients with de novo heterozygous K<sub>v</sub> 7.2 mutations are associated with early-onset epileptic encephalopathy and neurodevelopmental disorders characterized by intellectual disability, developmental delay and autism.