Parkinsonism in Spinocerebellar Ataxia Type 6

Characterization of the Parkinsonism and Other Non-ataxia Spectrum and Striatal Dopaminergic Degeneration in Spinocerebellar Ataxia Type 6

The spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of dominantly inherited progressive ataxia disorders. More than 30 different gene loci have been identified so far. The most common SCAs, which together account for more than half of all affected families, are SCA1, SCA2, SCA3, and SCA6. Each of these disorders is caused by a translated CAG repeat expansion mutation. SCA1, SCA2, and SCA3 usually have an onset between 30 and 40, and SCA6 usually begins at the age of 50 to 60. In addition to progressive ataxia, SCA1, SCA2, and SCA3 frequently present with additional non-ataxic symptoms, including parkinsonism. Carbidopa/levodopa was found to have a good therapeutic effect on parkinsonism.

The SCA6 used to be considered a pure cerebellar disorder. However, a recent large study on natural history of SCAs found that patients with SCA6 often had nonataxia symptoms, an observation that challenges the view that SCA6 is a purely cerebellar disorder. Parkinsonism in SCA6 was rarely reported, except in a case serial, or a small size study in Korean patients.

Dopamine transporter (DAT) is a very reliable dopaminergic neuronal marker. Reduction in DAT density detected by I123 SPECT DaTscanTM in the dopaminergic neuron terminal striatum was reported in one small size study consisting of eight SCA6 patients in Korea. There was also a PET study using different radioligand for DAT in a small group of SCA6 patients in Germany, which found sub-clinical change in DAT density in some patients with SCA6.

There has been no study so far in the US on parkinsonism and other non-ataxia spectrum and striatal dopaminergic damage in SCA6, probably because non-ataxia feature of SCA6 hasn't received much attention, and also because DaTscanTM hasn't been clinically available in US until recently. The only two published studies on SCA6 and DAT were from Korea and Germany, which were of small subject size. There has been no treatment available for SCA6 so far.

Our hypothesis is that parkinsonism and other non-ataxia spectrum and striatal dopaminergic neurodegeneration are part of the SCA6 disease spectrum.

Study Overview

• Status: Completed
• Conditions: Spinocerebellar Ataxia Type 6

Detailed Description

Specifically, we would expect to see

1. Parkinsonism and other non-ataxia symptoms are more commonly present in SCA6 patients than we used to think.
2. Parkinsonism is associated with the loss of DAT in striatum.
3. Parkinsonism and other non-ataxia symptoms are also associated with the expanded allele repeat number, the disease duration, and the severity of ataxia, in addition to DAT loss.

• Study Type: Observational
• Enrollment (Actual): 20

Contacts and Locations

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60637
      • University of Chicago

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

SCA6 patients and healthy controls.

Description

Inclusion Criteria:

• Patients 18 years old or older with progressive ataxia and positive genetic test for SCA6 will be recruited. Those who take medications known to affect DAT binding, such as Ritalin, Cocaine, and Adderall will be excluded. Those taking SSRIs for depression will be asked to stop the medications for at least 24 hours before the DaTscanTM. All study patients will have the decision making capability to understand the study and requirements and consent for themselves.

The age-matched controls will most likely be the patients' spouses. However friends or family members may also serve as controls if needed. Control subjects will have no ataxia, parkinsonism, myoclonus and other focal neurological symptoms and deficits.

Exclusion Criteria:

• Subjects who don't meet the inclusion criteria.

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Control
• Time Perspectives: Cross-Sectional

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
SCA6 and control
SCA6 or controls; Twelve SCA6 patients and 8 controls to be studied

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The primary outcome would be the clinical feature of the parkinsonism and change in DAT density in putamen and caudate	The UPDRS-II and -III scores	10 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The secondary outcome would be the INAS score	INAS score and its association with the DAT density and UPDRS scores	10 months
The secondary outcome would also be the SARA score	The SARA score and its association with the DAT density and UPDRS scores	10 months

Collaborators and Investigators

• Sponsor: University of Chicago
• Investigators: Principal Investigator: Tao Xie, MD PhD, University of Chicago

Study record dates

Study Major Dates

• Study Start: July 1, 2013
• Primary Completion (Actual): April 1, 2015
• Study Completion (Actual): April 1, 2015

Study Registration Dates

• First Submitted: August 27, 2013
• First Submitted That Met QC Criteria: August 29, 2013
• First Posted (Estimate): September 4, 2013

Study Record Updates

• Last Update Posted (Estimate): April 28, 2015
• Last Update Submitted That Met QC Criteria: April 27, 2015
• Last Verified: April 1, 2015

More Information

Terms related to this study

• Keywords: SCA6, parkinsonism, Datscan
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurologic Manifestations; Genetic Diseases, Inborn; Basal Ganglia Diseases; Movement Disorders; Neurodegenerative Diseases; Dyskinesias; Spinal Cord Diseases; Heredodegenerative Disorders, Nervous System; Cerebellar Diseases; Ataxia; Parkinsonian Disorders; Cerebellar Ataxia; Spinocerebellar Ataxias; Spinocerebellar Degenerations
• Other Study ID Numbers: 12-1335