Rocket Study: A Study to Characterize Biomarkers and Disease Progression in Participants With Pelizaeus-Merzbacher Disease

This study is collecting information to better understand the progression of Pelizaeus-Merzbacher Disease (PMD), a rare genetic brain disease that affects the development of myelin — the protective sheath around nerve fibers. The disease primarily affects males and causes progressive problems with movement and development. By tracking biological markers and disease progression in children with PMD, researchers hope to develop better tools for measuring the disease and potentially testing future treatments. You may be eligible if: - Your child (or you, as the child) is male and between 6 months and 17 years of age - Your child has a confirmed genetic diagnosis of PMD with PLP1 gene duplication - The clinical presentation is consistent with classic PMD - A parent or caregiver can provide informed consent and attend all study visits - There are no contraindications to lumbar punctures, blood draws, brain imaging, or sedation if needed You may NOT be eligible if: - Your child has clinically significant abnormalities outside of PMD on medical exam - Your child has more than 2 copies of the PLP1 gene - Your child has any other condition that, in the investigator's opinion, would make participation unsafe or interfere with the study Talk to your doctor to see if this trial is right for you.