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GENATLAS PHENOTYPE
last update : 04-01-2013
Symbol SCA17
Location 6q27
HGNC id 15735
Name spinocerebellar ataxia 17
Other name(s) Huntington disease-like 4
Corresponding gene TBP
Other symbol(s) HDL4
Main clinical features
  • bradykinesia, dementia, psychosis, dysmetria (early onset)
  • disorder characterized by cerebellar, extrapyramidal, pyramidal as well as psychiatric signs
  • degeneration of the grey matter centred around mesial cerebellar structures, occipito-parietal structures, the anterior putamen bilaterally, the thalamus and other parts of the motor network, reflecting the cerebellar, pyramidal and extrapyramidal signs
  • associated to smooth pursuit impairment and saccadic disorders (PMID: 17846415))
  • mild to severe cognitive deficits, choreic movements; pyramidal signs, bradykinesia and dystonia were observed in approx 50% of the cases; at MRI cortical and cerebellar atrophy in all patients, whereas neurophysiological examination excluded signs of peripheral nervous system involvement; oculomotor abnormalities, characterized by impairment of smooth pursuit, defects in the saccade accuracy, normal saccade velocity, hyperreflexia of vestibuloocular reflexes, and absence of nystagmus (PMID: 17934876))
    • Genetic determination autosomal dominant
    Related entries . including typical cases of Parkinson disease, Huntington-like and variant of Creutzfeldt -Jakob phenotypes
    Function/system disorder neurology
    Type disease
    Gene product
    Name TATA Box binding protein
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    repeat expansion   other triplet CAG repeat amplification > 42(47-63)
    Remark(s)
  • polyglutamine disease caused by CAG repeat expansion in TBP (TATA binding protein)
  • NFYA could be a target of mutant TBP in SCA17, because NFYA dysfunction was indicated in SCA17 cells as HSPA5 promoter activity reduced along with TBP aggregate formation (PMID: 22530004))
  • expression of the mutant TBP in Purkinje cells is sufficient to produce cell degeneration and an ataxia phenotype, and constitutes a good model for better analysis of the neurodegeneration in SCA17 (PMID: 21554323))