C9orf72 and amyotrophic lateral sclerosis: Several ALS genes have been implicated in the innate immune response specifically; for example C9ORF72 is highly expressed in myeloid cells [57, 66], conditional myeloid deletion of OPTN results in dysmyelination and axonopathy [32], and removal of mutant SOD1 from microglia prolongs lifespan in transgenic mice [7].