SIGMAR1 and Motor neuron atrophy: For example, mutations in the Sigma 1 receptor (SIGMAR1) related to frontotemporal lobar degeneration (FTLD), co-occurring with ALS (FTLD-ALS) [82] and juvenile ALS [83], cause the disruption of MERCs followed by perturbation of Ca2+ homeostasis, activation of ER stress and ultimately motor neuron degeneration [84].