SYN1 and tetanus: The main findings of the present study are as follows: membrane abnormalities (lipid peroxidation and disordering) and upregulation of presynaptic proteins (SNAP-25 and synapsin 1) are early structural signs of a nascent pathology of diaphragm NMJs; a decrease in both synaptic vesicle exocytosis and compensatory endocytosis upon intense motor nerve activity as well as a deficiency in the recovery of neurotransmitter release after tetanus were present in the NMJs of ΔFUS(1-359) mice at the pre-onset stage (Figure 8).