Study of VYNT-0126 in the Treatment of Rett Syndrome in Adult Patients

Inclusion Criteria: Females age 18-45 (inclusive) Diagnosis of classic/typical Rett syndrome with a documented mutation of the MeCP2 gene Severity rating of between 10 and 36 (Rett Syndrome Natural History/Clinical Severity Scale) Concomitant medications (including approved medications for treatment of Rett syndrome) must be stable for >4 weeks prior to enrollment Able to receive liquid study drug orally or via gastrostomy tube (G-tube) Exclusion Criteria: Actively undergoing neurological regression; Abnormal QT interval, prolongation or significant cardiovascular history Excluded concomitant medications Current clinically significant (as determined by the investigator). cardiovascular, endocrine, hepatic, renal, or respiratory disease Gastrointestinal disease which may interfere with the absorption, distribution, metabolism or excretion of the study medication History of, or current cerebrovascular disease or brain trauma History of, or current, malignancy Clinically significant abnormalities in safety laboratory tests, vital signs, or ECG, as measured at screening or baseline Any condition which in the investigator's opinion would affect the ability of the subject to participate in the study Allergy to VYNT-0126 or any ingredients of the liquid formulation