Single Participant Study of an Experimental ASO Treatment for TUBB4A-related Leukodystrophy

Inclusion Criteria: * Informed consent/assent provided by the participant (when appropriate), and/or participant's parent(s) or legally authorized representative(s). * Ability to travel to the study site and adhere to study-related follow-up examinations and/or procedures and provide access to participant's medical records. * Clinical phenotype and neuroimaging consistent with a diagnosis of TUBB4A-related leukodystrophy/Hypomyelination with Atrophy of the Basal Ganglia and Cerebellum (H-ABC) * Documented genetic mutation in TUBB4A Exclusion Criteria: * Participant has any known contraindication to or unwillingness to undergo lumbar puncture * Use of investigational medication within 5 half-lives of the drug at enrolment * Participant has any condition that in the opinion of the Site Investigator, would ultimately prevent the completion of study procedures.