This microglia-induced A1 astrocytic subtype is characterized by increased expression of complement component 3 (C3) and has been identified in human patients and mouse models of Alzheimer’s disease (AD), Huntington’s disease, amyotrophic lateral sclerosis, multiple sclerosis, Parkinson’s disease, prion disease and frontotemporal dementia6,8–10. The gene discussed is C3; the disease is multiple sclerosis.