To gain insight into the role of highly expressed EphA4 in iPSC-derived motor neuron death in MND, we next determined whether the iPSC-derived motor neurons from the MND patient carrying a SOD1E101G mutation were more vulnerable to oxidative stress, the most common stress observed under MND conditions, than iPSC-derived motor neurons from a healthy control [34,35]. This evidence concerns the gene EPHA4 and mild neurocognitive disorder.