Depletion of the microbiome has been shown to affect models of neurologic diseases, including mouse models of multiple sclerosis (MS), Parkinson’s disease (PD), Alzheimer’s disease (AD), and the C9orf72 model of ALS, all of which show less disease when treated with antibiotics or when raised under germ free conditions [9–14]. Here, C9orf72 is linked to Alzheimer disease.