Whether in the AD brain, intracellular Aβ - either in mitochondria or in the cytoplasm - is present at sufficiently high quantities to have a decisive role in disease is a matter to debate that has been revived by the recent analysis of Aβ plaque-forming 3xTg-AD using a panel of Aβ- and APP-specific antibodies [54]. The gene discussed is APP; the disease is Alzheimer disease.