| Main features described as dysarthria, writing difficulties, limb ataxia, and commonly nystagmus and saccadic abnormalities. The disease typically presents in the fourth decade. Ataxia gradually progresses and additional features may emerge including proprioceptive loss, hypoactive reflexes, ophthalmoparesis, and mild optic neuropathy. Initial presentation with blepharospasm, oromandibular dystonia, and retrocollis preceding ataxia has been reported. Caused by CAG repeat expansions in the ATXN1 gene region on chromosome 6p23. |
