Personalized Antisense Oligonucleotide Therapy for A Single Participant With ATN1 Gene Mutation

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. * Genetically confirmed Dentatorubral-pallidoluysian atrophy (DRPLA) due to ATN1 mutation Exclusion Criteria: * 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.