Genetic tests: how far should we go? A case of late-onset Friedreich's disease.

Two sisters developed isolated cerebellar ataxia with pyramidal signs and p reservation of reflexes at 49 and 63 years of age. Presence of two abnormal expansions GAA on both allels of the frataxine gene led to the diagnosis o f Friedreich ataxia. These cases demonstrate the place of genetic tests in the diagnosis of late onset autosomal recessive ataxia.