The disclosure provides a method of treating a mammal having a genetic epileptic disorder, comprising chronically administering a pharmaceutically acceptable pregnenolone neurosteroid to a mammal having a genetic epileptic disorder in an amount effective to reduce the seizure frequency in the mammal. In certain preferred embodiments, the mammal is a human patient who has a CDKL5 genetic mutation. In certain preferred embodiments, the patient has a low endogenous level of a neurosteroid(s). In certain preferred embodiments, the pregnenolone neurosteroid is ganaxolone.