Walsh & Hoyt: Heriditary Ataxias

The inherited ataxias represent a group of chronic progressive neurodegenerative conditions involving the cerebellum and its connections. The most common classification of the hereditary ataxias is by pattern of inheritance: autosomal dominant (most common), autosomal recessive, X-linked, and maternal (mitochondrial). Advances in biochemical and genetic analysis reveal a wide variability of clinical signs and neuropathology, even within families, and the overlap of clinical and pathologic phenotypes in disorders now known to be caused by different genetic defects makes diagnostic classification by phenotype often inaccurate. A genomic classification by chromosomal location is available for many of these disorders, and the abnormal gene products involved are under investigation. Optic atrophy is not uncommon among individuals with the hereditary ataxias.