Personalized Antisense Oligonucleotide for A Single Participant (nL62541) 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