A New Hypothesis of the Etiology of Amyotrophic Lateral Sclerosis

• Evidence is accumulating that a number of previously unexplained human diseases may arise from a deficiency of DNA repair enzymes. Studies on the motoneurons of patients with amyotrophic lateral sclerosis (ALS), and those of an animal model of motoneuronal degeneration, the wobbler mouse, indicate the presence of major abnormalities of RNA metabolism. We advance the hypothesis that the primary abnormality in ALS is the accumulation of abnormal DNA, which is unable to undertake normal transcription, in motoneurons. This abnormal DNA may arise from a deficiency of an isozyme of one of the DNA repair enzymes.