The clinical spectrum of Friedreich's ataxia in German families showing linkage to the FRDA locus on chromosome 9

Abstract

The clinical features of Friedreich's ataxia are described and reevaluated in a group of 14 German patients from 9 independent families. In contrast to previous studies, demonstration of linkage to the Friedreich's ataxia locus (FRDA) on chromosome 9p allowed confirmation of the genetic homogeneity of the disease in the patients under study. Marked variability within families was observed for age of onset of the disease (4-24 years) and for age of becoming wheelchair bound (17-37 years). Electrocardiographic changes were present in all and echocardiographic changes in 50% of the patients. Pathological changes of visual evoked potentials were detected in only 50% of the patients while brainstem auditory evoked potentials and somatosensory evoked potentials were always abnormal.

Hereditary optic neuropathies

“…Evidence of optic neuropathy is present in up to two-thirds of cases of Friedreich's ataxia, although severe visual loss is uncommon. [168][169][170][171][172][173][174] A condition resembling Friedreich's ataxia associated with decreased vitamin E levels has been localized to chromosome 8, and also includes some patients with optic atrophy. 175 Vitamin E supplementation of these patients may be efficacious early in the course of the disease.…”

Friedreich's Ataxia: Clinical Aspects and Pathogenesis

“…The severity of the neurophysiological abnormalities consequent to the axonal sensory neuropathy does not correlate with disease duration, indicating that the atrophy of sensory neurons is nonprogressive.32 Degeneration of peripheral and central sensory fibers also results in dispersion and delay of somatosensory evoked potentials ( S E P S ) .~~ Brain stem auditory evoked potentials (BAEPs), beginning from the most rostra1 component, wave V, progressively deteriorate in all patients.13.87 Visual evoked potentials (VEPs) are commonly (50-90%) reduced in amplitude with a normal P 100 latency. 13,[56][57][58]87 In all cases, central motor conduction is slower than normal,@ and, contrary to the sensory involvement, this slowing becomes more severe with increasing disease duration.32…”