title: Spinocerebellar ataxia type 17 associated with an expansion of 42 glutamine residues in TATA-box binding protein gene.
abstract: BACKGROUND
  Spinocerebellar ataxia type 17 (SCA17) is caused by abnormal expansions of CAG/CAA trinucleotides within the TATA-box binding protein gene (TBP). The currently accepted critical threshold of abnormal expansions is ≥43.
  
  
  OBJECTIVE
  To investigate the minimal CAG/CAA expansion within the TBP in SCA17.
  
  
  RESULTS
  285 patients with autosomal-dominant ataxia were examined, and abnormal or borderline expansions of CAG/CAA within TBP in eight cases were found. Of those, four patients from three families had exactly 42 CAG/CAA trinucleotides, that is, one codon less than the currently accepted critical threshold of 43. The four patients presented with a relatively benign phenotype. All had dysdiadochokinesia and dysarthria. Mild gait ataxia was observed in three of the four patients.
  
  
  CONCLUSIONS
  The reference definition of at least 43 CAG/CAA codons for pathological SCA17 alleles should be lowered to 42.
authors.affiliation: Institut für Humangenetik, Justus-Liebig Universität Giessen, Giessen, Germany. dagmar.nolte@humangenetik.med.uni-giessen.de
authors.forename: D
authors.initials: D
authors.lastname: Nolte
authors.forename: E
authors.initials: E
authors.lastname: Sobanski
authors.forename: A
authors.initials: A
authors.lastname: Wissen
authors.forename: J U
authors.initials: JU
authors.lastname: Regula
authors.forename: C
authors.initials: C
authors.lastname: Lichy
authors.forename: U
authors.initials: U
authors.lastname: Müller
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D001284:Atrophy; D002531:Cerebellum / Q000473:pathology; D002869:Chromosome Aberrations; D003062:Codon; D005260:Female; D005799:Genes, Dominant / Q000235:genetics*; D005973:Glutamine / Q000235:genetics*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D019683:Penetrance; D020754:Spinocerebellar Ataxias / Q000175:diagnosis / Q000235:genetics*; D035181:TATA-Box Binding Protein / Q000235:genetics*; D019680:Trinucleotide Repeat Expansion; D055815:Young Adult
chemical_list: D003062:Codon; D035181:TATA-Box Binding Protein; D005973:Glutamine