The inherited ataxias and the new genetics.

The powerful new tools of genetic investigation are steadily expanding our understanding of the molecular basis of inherited neurological disease. This is particularly so in the context of the inherited ataxias, in which nosological difficulties are beginning to be resolved by a genetically based classification. Harnessing the new knowledge will bring further rewards, including molecular genetic diagnosis, definition of clinical phenotypes, elucidation of pathophysiology, and the possibility of new treatments. Many metabolic disorders include ataxia as a more or less prominent feature. Traditionally it has been useful to distinguish these disorders from the "idiopathic" inherited ataxias, although the distinction is already seeming artificial as pathological mechanisms are elucidated. This review considers the impact of the new knowledge on the inherited ataxias previously considered idiopathic.