CHRNA4 and Intellectual disability: Patients with these KCNT1 mutations tend to exhibit an earlier age of onset (20 months to 9 years), a higher incidence of early-onset refractory epilepsy in their family history, higher rates of comorbid intellectual disabilities and behavioral abnormalities, higher drug resistance rates, and more complete penetrance than patients with nAchR mutant-derived SHE (12, 14).