C9orf72 and hereditary spastic paraplegia: Mitochondrial transport deficits are linked with several neurodegenerative disorders, such as Alzheimer’s and Huntington’s disease [43, 79], hereditary spastic paraplegia [21], Charcot–Marie–Tooth disease [19], as well as ALS with SOD1, TARDBP, and FUS mutations, and ALS with hexanucleotide repeats in C9orf72 [22, 24, 30, 47].