Dispute diagnosis of Friedreich's ataxia.

To the Editor .—I would like to question respectfully the article entitled "Auditory Function in Friedreich's Ataxia: Electrophysiologic Study of a Family" by Shanon et al published in the AprilArchives(1981;107:254-256). First, the inherited ataxias are a large, diverse, heterogeneous group of disorders. 1 Friedreich's ataxia forms a subgroup with rather specific symptoms. 2 Scientifically, it is important to separate patients with Friedreich's ataxia from others with inherited ataxias. However, Shanon et al do not describe in this family the typical scoliosis, cardiomyopathy, diabetes, corticospinal tract dysfunction, and other characteristics. Without the usual recessive inheritance pattern, these other features are important for making a diagnosis. As suggested by Barbeau, 2 the eponym "Friedreich's" should be avoided in atypical families. The second difficulty I have is with the latencies of their auditory brainstem potentials (ABPs). On close inspection, the latencies seem to be within generally accepted normal limits 3 in