The Marigold Study is a global, double-blind, placebo-controlled, Phase 3 clinical trial that will enroll approximately 70 patients between the ages of 2 and 21 with a confirmed disease-related CDKL5 gene variant. Patients will undergo a baseline period before being randomized to receive, in addition to their existing anti-seizure treatment, either ganaxolone or placebo for 17 weeks. Following the treatment period, all patients that meet certain eligibility requirements will have the opportunity to receive ganaxolone in the open label phase of the study. The study's primary efficacy endpoint is percent reduction in seizures. Secondary outcome measures will include non-seizure-related endpoints to capture certain behavioral and sleep disturbances that have been seen in previous clinical studies with ganaxolone.