Parkinsonism in Spinocerebellar Ataxia Type 6
| Status: | Completed |
|---|---|
| Conditions: | Neurology, Neurology |
| Therapuetic Areas: | Neurology |
| Healthy: | No |
| Age Range: | 18 - Any |
| Updated: | 4/13/2015 |
| Start Date: | July 2013 |
| End Date: | May 2014 |
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.
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.
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.
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.
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.
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