RT‐qPCR analysis confirmed that Aif1 (Figure 2c) and Csf1r (Figure 2d) mRNA expression was significantly increased in the brains of terminally‐affected Csf1rWT mice when compared to age‐matched uninfected controls, but remained almost undetectable in the brains of Csf1rΔFIRE mice even at the terminal stage of prion disease. The gene discussed is AIF1; the disease is prion disease.