Similarly, the SOD1-G93A mouse models of ALS were considered to be in the presymptomatic stage at a mean age of 56 days, began to show signs of symptom exaggeration (impairment in paw grip strength tests and body weight loss) at about 100 days (onset stage), and the disease further progressed thereafter (symptomatic and end stages) (85). This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.