C9 and amyotrophic lateral sclerosis: Thus, the authors argued that microglial impairment from decreased C9ORF72 expression directly contributed to neurodegeneration in C9-ALS.362 Although the loss of C9orf72 alone is insufficient to cause ALS motor deficits,363 the loss of function of C9ORF72 may lead to microglial dysfunction, which may accelerate disease progression in C9ALS/FTD patients.