Hereditary ataxias are clinically and genetically a very heterogeneous group of diseases that are associated with all known modes of inheritance. In addition to the more common, usually late-starting, autosomal dominant spinocerebellar ataxias (SCAs) caused by CAG triplet repeat expansions, a large number of genes are found whose pathogenic variants lead to a highly variable appearance: slowly progressive ataxic gait disorders, often accompanied by limited coordination of hands, speech and eye movement, mostly due to cerebellar atrophy and spinocerebellar or spinal cord degeneration. Degeneration of other parts of the central and peripheral nervous system (pyramidal tracts, basal ganglia) may also be present, resulting in non-cerebellar symptoms such as polyneuropathy, spasticity, etc. Many subtypes overlap with regard to their clinical appearance.
The most frequent ataxia genes ATXN1, ATXN2, ATXN3, CACNA1A, ATXN7, TBP, (after consultation: FXN and FMR1) are analyzed first with regard to triplet repeat expansions.
Sun et al. 2018, Genet Med. 21:195 / Nibbeling et al. 2017, Brain 140:2860 / Beaudin et al. 2017, Cerebellum & Ataxias 4:3 / Ashizawa et Xia 2016, Continuum (Minneap Minn) 22:1208