Early onset hereditary ataxias of unknown etiology. Review of a personal series.

Among 300 patients affected by hereditary ataxia, 94 received the diagnosis of Friedreich's disease, 12 of Late Onset Friedreich's disease, 27 of Early Onset Cerebellar Ataxia with retained tendon reflexes, 10 of Progressive Myoclonic Ataxia, 4 of Ataxia with hypogonadism and 2 of Ataxia with hearing loss. Only Friedreich's disease appears clinically homogeneous, whereas the others are not specific entities and each of them probably includes different diseases.