Spinocerebellar ataxias (SCAs) are progressive neurodegenerative hereditary disorders that result in degeneration of the cerebellum and sometimes the brain stem or spinal cord. Most SCAs are autosomal dominant, and many result from expanded CAG trinucleotide repeats. There are over 30 clinically and genetically distinct autosomal dominant cerebellar ataxias.

Cerebellar symptoms are similar among the various disorders and include gradual onset of gait and balance dysfunction, dysarthria, blurry vision and/or diplopia, and clumsiness of the hands. Other manifestations may help point to specific mutations such as upper motor signs, peripheral neuropathy, visual loss, dementia, tremor, myoclonus, and/or areflexia.

Age of onset of autosomal dominant SCAs is variable, but symptoms tend to emerge in adulthood. Disease severity and progression often depend on the type of SCA, although nearly all of the autosomal dominant ataxias do eventually progress to severe disability. There is no cure, and treatment is symptomatic, often incorporating physical, occupational, and speech therapy and assistive devices.

Related topics: Friedreich ataxia, Ataxia-telangiectasia syndrome, Fragile X-associated tremor ataxia syndrome