Repeat amplification mutations in the C9orf72 of chromosome 9 cause ALS, and repeat amplification of the C9orf72 gene in autopsy samples of ALS patients has been observed to cause the dysregulation of ETC gene transcription and reduce the expression of complexes I and IV, resulting in impaired energy metabolism as well as the dysregulation of axonal homeostasis [107,108]. Here, C9orf72 is linked to amyotrophic lateral sclerosis.