Hereditary Ataxias!!!
Spinocerebellar ataxias (SCA)
“SCA1 …. the unstable CAG trinucleotide repeat expansion”
American geneticist Harry T. Orr
SCA definition
Worldwide distribution of SCA subtypes
21% SCA3, Brazil & Portugal
15% SCA2, India & Singapore
15% SCA6, Japan & Germany
6% SCA1, South Africa
5% SCA7, South Africa
3% SCA8, worldwide
<1% rare
SCA 10, SCA 12, SCA 14, SCA17
SCA1
SCA2
SCA3 “ophthalmoplegia, vestibular involv, fasciculations, neuropathy, spasticity, extrapyramidal signs” -severe vertigo & muscle cramping -Machado-Joseph disease -most freq SCA -Portuguese pop -anticipation w/ paternal transmission
SCA6 “downbeat nystagmus & vestibular involvement” - after age 50y, onset - episodic ataxia - severe vertigo - CACNA1A - anticipation is not seen
SCA7 “early slowed oculomotor saccades, spasticity” - infantile onset - associated w/ seizure & retinopathy - macular dystrophy
SCA8
“saccadic dysmetria and gaze-evoked nystagmus”
- mild disease
- ATXN 8, ATXN8 OS
- AD
- maternal anticipation
- associated w/ seizures
- ATXN 10
- Mexican population
- paternal anticipation
- SCA2&SCA10
SCA12
“action tremor, progressive ataxia, subtle parkinsonism”
- PPP2R2B
- Agarwal community
SCA14 - PRKCG - AD
SCA17
“extrapyramidal signs”
- dementia
- TBP
- AD
SCA27b
- Late adult-onset
- downbeat nsytagmus
Algorithm - age
Algorithm – clinical manifestation
Algorithm – oculomotor sign
Ophthalmologic manifestations of SCA
Algorithm regarding AD or AR
- according to the family inheritance order, the panel