FIS1 and Alzheimer disease: Interestingly, increased levels of the fission proteins Drp1 and Fis1 and decreased fusion proteins Mfn1, Mfn2 and Opa1 are found in individuals with AD (Manczak et al., 2011), where Fis1 and Drp1 display aberrant interactions with the AD-related proteins β-amyloid and hyperphosphorylated tau (Manczak and Reddy, 2012).