Mouse Genome Informatics
tg1
    Tg(SCA7)c92QAls/0
involves: C3H/HeJ * C57BL/6
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
mortality/aging
• death between 13 and 34 weeks in most affected mice

growth/size/body
• most affected mice are smaller as ataxia progresses

vision/eye
• retinas show increased numbers of apoptotic photoreceptor cells
• loss of cone photoreceptors
• photoreceptor cell degeneration: cone-rod dystrophy type of retinal degeneration
• mutants exhibit progressive thinning of the outer nuclear layer starting at 6-11 weeks of age, with some regions narrowing to as few as six nuclei across
• cone-initiated responses are degraded faster than rod-driven responses
• mildly affected mutants show a reduction in cone-initiated responses while maintaining normal rod responses
• moderately affected mutants show a further reduction in cone-initiated and ultimately show an absence of both the cone and rod responses to the brightest light flash
• moderately affected mutants show a slight reduction in rod-initiated responses and ultimately show an absence of both the cone and rod responses to the brightest light flash
• age of blindness onset is 9-13 weeks of age

nervous system
• Purkinje cells are flattened and exhibit less dendritic arborization, and nuclei have occasional invaginations and appear granular
• however, no significant neuronal loss is observed
• severe Purkinje cell degeneration (smaller and shrunken) at 20 weeks of age, despite the absence of expression of the polyglutamine-expanded SCA7 in Purkinje cells
• retinas show increased numbers of apoptotic photoreceptor cells
• loss of cone photoreceptors
• photoreceptor cell degeneration: cone-rod dystrophy type of retinal degeneration

behavior/neurological
• mutants become less explorative
• mutants startle easily
• 50% of 12 week old mutants are claspers in the clasping test
• mutants eventually develop a chronic whole-body tremor
• 50% of 12 week old mutants fail in a ledge test
• impairment in rotarod function by 8 weeks of age which worsens over time
• unsteady gait progresses to a wide-based stride with occasional falling
• 50% of 12 week old mutants are inactive
• an unsteady gait develops beginning at 8-15 weeks of age

Mouse Models of Human Disease
OMIM IDRef(s)
Spinocerebellar Ataxia 7; SCA7 164500 J:71971 , J:77530