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  • 1.  Likely SCA 7

    Posted 06-26-2025 12:43

    I have a 60 YO F who likely has SCA 7.

    Known cone dystrophy diagnosed at age 12, multiple family members affected with cone dystrophy, not had genetic testing.

    She notes she has childhood onset nystagmus but recently has oscillopsia, incoordination, using her cane all the time and unable to read.

    Exam shows rotary nystagmus, macular scarring OU and ataxia on finger nose testing and dysmetria. She is unwilling to undergo genetic testing for financial reasons. Neuroimaging, CSF testing unremarkable.

    Is it common for SCA 7 to start with visual symptoms during teens and then present ~age 60 with cerebellar dysfunction?

    What resources can I recommend for this patient? She herself works for state services for the blind and would like to know of more resources. Looking forward to your inputs. 

    Thank you,

    Shruthi Harish



  • 2.  RE: Likely SCA 7

    Posted 06-29-2025 23:42

    SCA7 is a triplet repeat disorder that is transmitted in an autosomal dominant fashion. It is possible to have reduced penetrance, depending on the number of repeats.

    In young onset, visual symptoms usually precede cerebellar symptoms and are typically severe. These patients have a reduced life expectancy, and I would expect ataxia by the 2nd or 3rd decade too. With older age onset, often cerebellar symptoms predominate and visual symptoms may not even develop.

    For SCA7 (and others, e.g., SCA2) helpful to look for slowed saccades and/or ophthalmoplegia.

    Also, keep in mind the spinal aspect of a spinocerebellar ataxia: look for upper and lower motor neuron findings, e.g., hyper- or hyporeflexia, spasticity, fasciculations, muscle loss).

    In your case, SCA7 is probably an unlikely diagnosis. Of course, genetic testing is reasonable, and could include SCA triplet expansion panel +/- ataxia gene panel +/- mitochondrial +/- exome.

    Best,

    Bart

     

     

    Bart K. Chwalisz, M.D.

    Neuro-ophthalmology, Headache Unit, and Skull Base Disorders Clinic. Division of  Neuroimmunology, Massachusetts General Hospital/Harvard Medical School

    https://www.massgeneral.org/neurology/treatments-and-services/inflammatory-neuroophthalmology-and-skull-base-disorders-clinic

    Neuro-ophthalmology, Massachusetts Eye & Ear Infirmary/Harvard Medical School

    Neurology, Martha's Vineyard Hospital

     

     

     




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  • 3.  RE: Likely SCA 7

    Posted 06-30-2025 14:27
    Hello,

    The cases I've seen had supranuclear palsy and several had severe exotropia or WEBINO.  The cerebellar appendicular findings did not delay by decades though; they presented closed to the visual findings.  Significant macular pigmentation was also present.

    Robert



    Original Message


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