Adult onset spinocerebellar ataxia in a Canadian movement disorders clinic.
BACKGROUND
The spinocerebellar ataxias (SCAs) are a genetically and clinically heterogeneous group of neurodegenerative disorders. Relative frequencies vary within different ethnic groups and geographical locations.


OBJECTIVE
1) To determine the frequencies of hereditary and sporadic adult onset SCAs in the Movement Disorders population; 2) to assess if the fragile X mental retardation gene 1 (FMR1) premutation is found in this population.


METHODS
A retrospective chart review of individuals with a diagnosis of adult onset SCA was carried out. Testing for SCA types 1, 2, 3, 6, 7, and 8, Dentatorubral-pallidoluysian atrophy (DRPLA), Friedreich ataxia and the FMR1 expansion was performed.


RESULTS
A total of 69 patients in 60 families were identified. Twenty-one (35%) of the families displayed autosomal dominant and two (3.3%) showed autosomal recessive (AR) pattern of inheritance. A positive but undefined family history was noted in nine (15%). The disorder appeared sporadic in 26 patients (43.3%). In the AD families, the most common mutation was SCA3 (23.8%) followed by SCA2 (14.3%) and SCA6 (14.3%). The SCA1 and SCA8 were each identified in 4.8%. FA was found in a pseudodominant pedigree, and one autosomal recessive pedigree. One sporadic patient had a positive test (SCA3).Dentatorubral-pallidoluysian atrophy and FMR1 testing was negative.


CONCLUSIONS
A positive family history was present in 53.3% of our adult onset SCA patients. A specific genetic diagnosis could be given in 61.9% of dominant pedigrees with SCA3 being the most common mutation, followed by SCA2 and SCA6. The yield in sporadic cases was low. The fragile X premutation was not found to be responsible for SCA.
Kraft
Scott
S
Movement Disorsders program, Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
Furtado
Sarah
S
Ranawaya
Ranjit
R
Parboosingh
Jillian
J
Bleoo
Stacey
S
McElligott
Karen
K
Bridge
Peter
P
Spacey
Sian
S
Das
Shyamal
S
Suchowersky
Oksana
O
D000328:Adult; D017668:Age of Onset; D000554:Ambulatory Care Facilities; D002170:Canada / Q000453:epidemiology; D004252:DNA Mutational Analysis; D005260:Female; D005808:Genes, Recessive; D005828:Genetics, Population; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D009154:Mutation; D012189:Retrospective Studies; D020754:Spinocerebellar Ataxias / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics