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Article History

Received: 1 December 2025

Accepted: 19 February 2026

First Online: 12 March 2026

Declarations

:

: The study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki. All participants or their legally authorized representatives provided written informed consent before participation in the study. The study was approved under a single-IRB provided by the University of Alabama, Birmingham Institutional Review Board (IRB #F150518001). A Certificate of Confidentiality was provided by the National Institute of Child Health and Development (NICHD). This work was not a clinical trial, but the non-interventional observational clinical study protocols were registered with Clinical Trials.Gov (NCT00299312, registration date 06 March 2006, and NCT02738281, registration date 22 November 2015).

: Not applicable.

: JLN received research funding from the National Institutes of Health, the International Rett Syndrome Foundation, and Rett Syndrome Research Trust; clinical trials with Acadia Pharmaceuticals Inc., GW Pharmaceuticals, Ionis Pharmaceuticals, and Taysha Gene Therapies; consultancy paid to his institution from Taysha Gene Therapies; personal consultancy for Acadia Pharmaceuticals Inc., Alcyone Lifesciences, GW Pharmaceuticals, Hoffmann-La Roche, Jazz Pharmaceuticals, Neurogene, Ovid Therapeutics, and Signant Health; and participated on data safety monitoring boards for clinical trials conducted by Ovid Therapeutics and Ultragenyx.AKP received research funding from the National Institutes of Health, the International Rett Syndrome Foundation, and Rett Syndrome Research Trust; participated in clinical trials funded by Acadia Pharmaceuticals and is presently participating in gene therapy trials funded by Taysha Gene Therapies and Neurogene. He is chair of the Data Safety Monitoring Board for the Ionis trial (ION440-CS1) in MECP2 Duplication Syndrome.TAB received research funding from GRIN2B Foundation, the International Foundation for CDKL5 Research, Loulou Foundation, the National Institutes of Health, Rocky Mountain Rett Association, and Simons Foundation; consultancy for Alcyone, AveXis, GRIN Therapeutics, GW Pharmaceuticals, the International Rett Syndrome Foundation, Marinus Pharmaceuticals, Neurogene, Ovid Therapeutics, Takeda Pharmaceutical Company Limited and Taysha; clinical trials with Acadia Pharmaceuticals Inc., GW Pharmaceuticals, IONIS, Marinus Pharmaceuticals, Neurogene, Ovid Therapeutics, and Rett Syndrome Research Trust; all remuneration has been made to his department.EDM received research support from the National Institutes of Health, Penn Orphan Disease Center, the International Rett Syndrome Foundation, Rett Syndrome Research Trust, International CDKL5 Research Foundation, Department of Defense, and the Loulou Foundation. He has been a site principal investigator for trials from Stoke Therapeutics, SK Life, Ionis, Zogenix (now UCB), Acadia Pharmaceuticals Inc., Takeda Pharmaceuticals, Epygenix Pharmaceuticals, and Marinus Pharmaceuticals. He has received personal compensation for consulting and advisory board participation from Acadia, Ionis, Taysha, and Neurogene and the preparation of CME activities for Medscape.SUP received research funding from the National Institutes of Health, the MECP2 Duplication Foundation, and the ActiGraph Corporation. She has been a consultant for Ionis Pharmaceuticals and Taysha Gene Therapies.CF has been a site investigator for clinical trials with Acadia Pharmaceuticals, Zogenix, Ionis Pharmaceuticals, Taysha Gene Therapies, and Neurogene. He has received personal compensation for consulting from Acadia Pharmaceuticals and Taysha Gene Therapies.SKM has no conflicts of interest.