Crossing the endogenous unedited wild type sod-1(+) allele on chromosome II into sod-1A4VM, sod-1H71YM or sod-1G85RM animals did not rescue paraquat-induced cholinergic motor neuron degeneration (Fig 3B, Part IV), consistent with a gain of toxic function mechanism in ALS sod-1 alleles. Here, SOD1 is linked to amyotrophic lateral sclerosis.