The goal of this clinical trial is to evaluate a specific antisense oligonucleotide medication in one patient with posterior column ataxia with retinitis pigmentosa. The main question it aims to answer is: what is the safety and tolerability of this medication in a single participant.

Inclusion Criteria:

• Informed consent/assent provided by the participant (when appropriate), and/or participant's parent(s) or legally authorized representative(s).
• Genetically confirmed FLVCR1-related disease.
• 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.

Exclusion Criteria:

• Allergy to any of the ASO components
• Participant has any condition that in the opinion of the Site Investigator, would ultimately prevent the completion of study procedures.