Elevated expression of mitochondrial fission genes, encoding dynamin-related protein 1 (Drp1) and fission 1 (Fis1), and reduced expression of the fussion ones, encoding mitofusin 1 (Mfn1), mitofusin 2 (Mfn2), optic atrophy 1 (Opa1), and Tomm40, have been detected in AD brains, fibroblasts from AD patients, neurons isolated from APP transgenic mice, and cell lines overexpressing APP [121–123]. The gene discussed is FIS1; the disease is Alzheimer disease.