Late onset spinal muscle atrophy--a sex linked variant of Kugelberg-Welander.

A syndrome of progressive muscular atrophy in reported in male members of a Caucasian family. Two affected members were examined in detail, one with post mortem. Fasciculations and atrophy of tongue as well as of the proximal limb muscles were observed, and there was profound weakness of the proximal muscles. The EMG and muscle biopsy were consistent with a neurogenic disease. The most pronounced lesion was in the lateral part of the anterior horn, with minimal involvement of the ventral portion of the anterior horns and sparing of the neurons of Clarke's column. Two earlier families with possible Kugelberg-Welander syndrome have been reported in which a sex-linked form also seems probable, and the varied inheritance pattern and uncertain pathological correlations suggest that the Kugelberg-Welander and familial amyotrophic lateral sclerosis both represent heterogenous neurological disorders.