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GENATLAS PHENOTYPE
last update : 11-03-2020
Symbol SCA7
Location 3p14.1
Name spinocerebellar ataxia 7
Other name(s) OPCA with macular degeneration and external ophthalmoplegia
Corresponding gene ATXN7
related resource Retinal Information Network
Other symbol(s) ADCA2, OPCA3
Main clinical features
  • with anticipation, characterized by ataxia, dysarthria, dysmetria, intention tremor
  • associated with pigmentary macular dystrophy or cone-rod dystrophy (autosomal dominant cerebellar atrophy type II) and ubiquinated aggregates intranuclear neuronal inclusions detected by 1C2 antibody directed against CAG repeat
  • adult-onset with progressive visual impairments
  • at neuropathological study, neuronal intranuclear inclusions bodies (NI) were observed in all cerebellar regions, in all parts of the cerebral cortex, and in telencephalic and brainstem nuclei
    • Genetic determination autosomal dominant
    Function/system disorder neurology
    Type disease
    Gene product
    Name ataxin 7
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    repeat expansion   other triplet CAG repeat amplification, intermediate alleles bearing 28-35 repeats which can expend to the pathological range during paternal transmission and pathologic 37 to 200 repeats, or highly amplified in infantile or juvenile-onset spinal cerebellar ataxia
    Remark(s) . polyglutamine-expanded ataxin-7-induced transcriptional dysregulation causes cerebellar dysfunction and ataxia (PMID: 19909779))
  • RELN could be involved in the tissue specificity of SCA7 (PMID: 23236151))
  • autophagy/lysosome pathway is impaired in neurons undergoing degeneration in SCA7 (PMID: 24859968))
  • polyQ-expanded ATXN7 forms insoluble aggregates that sequester USP22 into a catalytically inactive state, and then the impaired deubiquitination module (DUBm) loses the function to deubiquitinate monoubiquitinated histone H2B or H2A (PMID: 26195632))