The purpose of this research study is to learn more about a study drug that may affect patients with spinocerebellar ataxia type 3 (SCA3). This type of drug is called an antisense oligonucleotide. Eligible participants in this study will have the study drug injected into the fluid surrounding their spinal cord and brain through a fine needle placed in the spinal canal in the lower back. This procedure is called a lumbar puncture. After injection of the study drug, participants will be monitored in the hospital for 6 to 24 hours before going home. During the study, participants will receive study drug at up to 4 visits. Some of the assessments include: examinations of the brain and body, collection of blood, urine, and CSF (the fluid in the spine) samples, medical scans of the brain, and questionnaires about health and daily life.

You may be eligible for this study if you meet the following criteria:

• Conditions: Machado-Joseph disease, Spinocerebellar Ataxia
• Age: 18 years - 70 years
• Gender: All