Spinocerebellar Ataxia Type 17 (SCA17)

Record ID 32010000875
Authors' objectives:

The spinocerebellar ataxias (SCAs) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by limb and gait ataxia. More than 25 different types of SCA have been described, although the causative genes have not yet been identified for all types. SCA type 17 (SCA17), which accounts for approximately 0.5% to 1% of autosomal dominant SCA cases, is characterized by a variable combination of cerebellar ataxia, psychiatric symptoms (such as changes in personality, mood disorders, depression, hallucinations, and psychosis), and cognitive impairment (including dementia). In addition, movement disorders are prominent among those with SCA17 and can included dystonia (involuntary movements and prolonged muscle contractions), chorea (involuntary, irregular muscle contractions), choreoathetosis (chorea associated with twisting and writhing movements), and rigidity. Importantly, some individuals with SCA17 exhibit symptoms that are clinically indistinguishable from those seen in Huntington disease,
Parkinson disease, or Alzheimer disease. Additional features that may be seen in SCA17 patients include dysarthria (slow, distorted speech), dysphagia (difficulty swallowing), seizures, hyperreflexia, hypertonia, and urinary incontinence. SCA17 is caused by expansion of CAG/CAA sequence in the TATA-binding protein gene (TBP) located on chromosome 6 at band q27. In most individuals, this polyglutamine-encoding sequence includes 2 variable CAG tracts [(CAG)n] and interrupting CAA trinucleotides: (CAG)3 (CAA)3 (CAG)n CAA CAG CAA (CAG)n CAA CAG. Because of the CAA interruptions, the CAG/CAA expansion is typically stable when passed from parent to child, and genetic anticipation (an earlier age at onset and increased disease severity with successive generations) is not seen. Occasionally, the CAG/CAA repeat tract in affected individuals
lacks the CAA CAG CAA sequence between the 2 variable segments; in these cases, the repeat exhibits intergenerational instability and genetic anticipation can be seen.

Project Status: Completed
URL for project: http://www.hayesinc.com/
Year Published: 2009
English language abstract: An English language summary is available
Publication Type: Not Assigned
Country: United States
MeSH Terms
  • Humans
  • Spinocerebellar Ataxias
Organisation Name: HAYES, Inc.
Contact Address: 157 S. Broad Street, Suite 200, Lansdale, PA 19446, USA. Tel: 215 855 0615; Fax: 215 855 5218
Contact Name: saleinfo@hayesinc.com
Contact Email: saleinfo@hayesinc.com
Copyright: 2009 Winifred S. Hayes, Inc
This is a bibliographic record of a published health technology assessment from a member of INAHTA or other HTA producer. No evaluation of the quality of this assessment has been made for the HTA database.