Study of Adjunctive Ganaxolone Treatment in Children and Young Adults With CDKL5 Deficiency Disorder

Inclusion Criteria: * Genetically confirmed CDKL5 gene mutation, seizure onset by 1 year of age and lack of independent ambulation by 2 years of age * Failure to control seizures despite 2 or more anti-seizure medications * At least 16 seizures per 28 days of primary seizure types * On a stable regimen of 0-4 anti-seizure medications (Vagus nerve stimulator, ketogenic diet, and modified Atkins diet do not count towards this limit) * Additional Inclusion Criteria apply and can be discussed with study team Exclusion Criteria: * Previous exposure to ganaxolone * West Syndrome with hypsarrhythmia pattern on EEG or seizures predominantly of Infantile Spasms type * Use of adrenocorticotropic hormone (ACTH), prednisone or other glucocorticoid or use of moderate or strong inducers or inhibitors of CYP3A4/5/7 are prohibited * Use of tetrahydrocannabinol (THC) or cannabidiol (CBD) is prohibited during the double-blind phase, unless patient has a prescription of Epidiolex® * Exposure to any other investigational drug within 30 days or fewer than 5 half-lives prior to screening * Plasma allopregnanolone-sulfate (Allo-S) levels greater than or equal to 6.0 ng/ml at screening visit * Additional Exclusion Criteria apply and can be discussed with study team