SOD1 and amyotrophic lateral sclerosis: Large-scale genome-wide association studies (GWAS) have identified several susceptibility genes, including C9orf72, SOD1, and UNC13A. The ALS-related genes were implicated in altered protein homeostasis (SOD1), depositions of intranuclear RNA (C9orf72), and altered neuronal cytoskeletal dynamics (TUBA4A), leading to the death of upper and/or lower MNs in the brain, brainstem, and spinal cord (Brown and Al-Chalabi, 2017).