The genetic basis of ataxia.

The inherited ataxias can now be classified on the basis of genotype rather than phenotype. Clinical expression of the various disorders overlap one another, making a diagnostic classification based on phenotype inaccurate in many instances. A genomic classification as outlined here has provided order and clarity in this group of disorders previously classified on the basis of clinical features. It is expected that in the near future the abnormal gene products for these ataxias, the ataxins, will be identified and provide molecular insights for effective therapies.