Clinical Study of Cannabidiol in Children, Adolescents, and Young Adults With Fragile X Syndrome

This is a randomized, double-blind, placebo-controlled, multiple-center study, to assess the efficacy and safety of cannabidiol administered as ZYN002 for the treatment of children, adolescent, and young adult patients with Fragile X syndrome (FXS). Eligible participants will participate in up to an 18-week treatment period, where all participants will receive placebo or active study drug. Patients ages 3 to \< 30 years will be eligible to participate.

Inclusion Criteria: * Male or female children and adolescents aged 3 to \< 30 years, at the time of Screening. * Patient resides with caregiver who will continue to provide consistent care throughout the study. * Judged by the Investigator to be in generally good health at Screening based upon the results of medical history, physical exam, 12-lead ECG and clinical laboratory test results. -Laboratory results outside the reference range must be documented as not clinically significant by both the Investigator and Sponsor. * Participants must have a diagnosis of FXS through molecular documentation of full mutation of the FMR1 gene documented through genetic testing at Screening. * Patients with a history of seizure disorders must currently be receiving treatment with a stable regimen of no more than two anti-seizure medications (ASMs) for the four weeks preceding study Screening; or must be seizure-free for one year if not currently receiving ASMs. * Patients taking psychoactive medication(s) should be on a stable regimen of not more than three such medications for at least fours weeks preceding Screening and must maintain that regimen throughout the study. Psychoactive medications include (but are not limited to) antipsychotics, antidepressants, anxiolytics, attention-deficit / hyperactivity disorder (ADHD) medications, and medications for sleep. * If patients are receiving non-pharmacological, behavioral and/or dietary interventions, they must be stable and have been doing so for three months prior to screening. * Patients have a body mass index between 12-30 kg/m2 (inclusive) and patients with a body mass index \>30 kg/m2 and \