Natural History of Spinocerebellar Ataxia Type 7 (SCA7)

Objective: Spinocerebellar Ataxia, type 7 (SCA7) is an autosomal dominant neurodegenerative disease characterized by progressive ataxia, retinal degeneration, and marked genetic anticipation. The objectives of this study are to 1) establish a cohort of participants with molecularly-confirmed SCA7 in anticipation of future clinical trials, 2) create a repository of plasma, DNA, and skin fibroblast samples from the accrued cohort of SCA7 participants, 3) formulate clinical outcome measures for future studies, and 4) acquire and perform preliminary analyses of data that may advance our understanding of the progression of retinal and neurodegeneration associated with molecularly-confirmed SCA7. Study Population: Twenty-five (25) participants, ages 12 and above, with molecularly-confirmed SCA7 will be accrued for this study. Design: In this natural history study, participants will be followed for at least five years. Because three years may be required to enroll 25 participants, this study will last at least eight years. All participants will undergo a standardized medical/ophthalmic history and a complete baseline eye examination, including non-invasive electrophysiology (e.g., electroretinography), psychophysiology (e.g., microperimetry, static perimetry), and diagnostic imaging examinations (e.g., optical coherence tomography). In addition, participants will undergo a detailed neurology exam, neuroimaging (MRI, including special sequences) and consult with speech pathology and/or other rehabilitation services, audiology, and neuropsychology. To establish baseline, the participants will undergo two separate detailed eye examinations and a single neurology/neuroimaging examination within a one to two week period. Afterwards, they will return to the NEI clinic annually until the last-enrolled participant has completed a minimum of five study visits. Follow-up visits will consist of a single detailed eye exam, a single detailed neurology/neuroimaging exam, and follow-up with appropriate consultants. Participants may be seen at more frequent intervals at the investigators discretion, depending on the clinical and research situation. Participants will be required to submit a blood sample for research, and they will have the option to provide a skin biopsy to facilitate research at a cellular level. Outcome Measures: The primary outcome for this study is determination of the amplitude and time of photopic and scotopic responses on electroretinogram. Secondary outcomes include changes in visual acuity, microperimetry, peripheral visual field, color vision, macular thickness, and neurologic outcome variables. Exploratory outcomes for this study include: 1) the formulation of clinical outcome measures for future studies and 2) the acquisition and preliminary analysis of data that may advance our understanding of the progression of retinal and neurodegeneration associated with molecularly-confirmed SCA7. Cells from skin biopsies may be grown in the laboratory to better understand SCA7, including the evaluation of potential treatments.