In AD, Aβ overproduction causes an imbalance in mitochondrial dynamics, affecting the levels of Drp1, Opa1, Mfn1 and 2, both in vitro and in postmortem brains of AD patients (Wang et al., 2008, 2009), inducing mitochondrial fragmentation and an abnormal distribution of mitochondria inside neurons. The gene discussed is OPA1; the disease is Alzheimer disease.