Taking into account reports on abnormal accumulation of misfolded SOD1 in PD brains [16] and also of α-synuclein in ALS spinal cords [59, 60], there would be a shared pathomechanism between ALS and PD; indeed, sporadic and familial cases of motor neuron disease with parkinsonism have been occasionally reported (e.g. [61]). Here, SOD1 is linked to motor neuron disorder.