SOD1 and amyotrophic lateral sclerosis: In addition, a transgenic superoxide dismutase 1 (SOD1) mutant rat model of ALS showed focal loss of GLT-1 in the ventral horn of the spinal cord prior to the onset of motor neuron/axon degeneration (Howland et al., 2002), and there is evidence for decreased brain tissue concentration of glutamate and increased levels in the CSF of patients with ALS [for review refer to Heath and Shaw (2002)].