The proliferation of microglia in prion disease is regulated by the activation of CSF1R and the transcription factors PU.1 and CCAAT/enhancer-binding protein alpha (C/EBPα, being this system also active in human variant CJD and Alzheimer’s disease (AD; Gómez-Nicola et al., 2013; Olmos-Alonso et al., 2016). The gene discussed is CEBPA; the disease is early-onset autosomal dominant Alzheimer disease.