In 2017, Aoki and collaborators observed a lower number of multivesicular endosomes as well as a reduction in the number and secretion of exosomes in both ALS/FTD patient-derived fibroblasts and induced pluripotent stem cell-derived motor neurons carrying the C9orf72 hexanucleotide repeat expansion [84]. Here, C9orf72 is linked to amyotrophic lateral sclerosis.