Examples include Quinidine significantly decreased seizure frequency in a child with KCNT1-related epilepsy, Switching to a low fructose diet improved severe growth delay in a child with a dual diagnosis of hereditary fructose intolerance and Coffin-Siris syndrome, and Carnitine improved gastrointestinal symptoms in a child with KAT6A-related disorder. The gene discussed is KAT6A; the disease is hereditary fructose intolerance.