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 up to 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 neuropsychologic assessment.

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 reaches five
years of follow-up. Therefore, this study will require a minimum of five study visits.
Follow-up visits will consist of a single detailed eye exam and a single detailed
neurology/neuroimaging exam. 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.

- INCLUSION CRITERIA:

To be eligible, the following inclusion criteria must be met, where applicable.

1. Participant must be 12 years of age or older.

2. Participant must be able to understand and sign the protocol s informed consent
document on their own behalf OR, in the case of a minor, have a legal guardian/parent
with the ability to do the same.

3. Participant must be able to produce a recordable electroretinogram (ERG).

4. Participant must have the ability to cooperate the required testing. Participants
unable to cooperate with one or more tests may be included only at the discretion of
the Principal Investigator.

5. Participant must be willing and able to provide a blood sample.

6. Any female participant of childbearing potential must agree to have pregnancy testing
prior to undergoing MRI.

7. Participant has molecularly-confirmed, symptomatic SCA7, as defined by CAG repeat
expansion in the ATXN7 gene of greater than 35 repeats. Accrual will be biased towards
those with lower numbers of abnormal repeats (above 35 repeats) as they are most
likely to be able to cooperate with testing. Participants who have clinical findings
consistent with SCA7 and a relative who has had molecular diagnosis, may be included
in the study with subsequent confirmation of the number of repeats. Patients who have
clinical findings consistent with SCA7 but no molecular diagnosis may be evaluated
under an NEI screening, genetics bank, or evaluation and treatment protocol with
subsequent molecular diagnosis performed within six months of their initial visit.

EXCLUSION CRITERIA:

A participant is not eligible if any of the following exclusion criteria are present.

1. Participant is unable to cooperate with ophthalmic/neurologic testing, including
inability to undergo brain MRI without sedation.

2. Participant has comorbidity, unrelated to ocular pathology, compromising the ability
to view/image the retina and/or record an ERG.