APP and Alzheimer disease: In support to this possibility, there is epidemiological evidence of an association between air pollution exposure and the risk of developing Alzheimer’s disease that suggests an environmental involvement in the disease development [110,111]; but even more striking is a recent investigation showing that in the pathological neurons, the Alzheimer’s disease-related APP (amyloid precursor protein) gene occurred “mosaically” as thousands of genomic variants [112].