As shown in Fig 1, our results show that plasma NfH levels increase significantly during overall disease progression between 65–120 days in the SOD1G93A mouse model of ALS (Friedman test: p<0.0001) and that this increase in plasma NfH correlates with the loss of muscle force, decline in motor unit survival and most significantly, with the extent of motor neuron degeneration that occurs during later stages of disease. Here, NEFH is linked to amyotrophic lateral sclerosis.