APP and familial Alzheimer disease: The transdifferentiation efficiency of fibroblasts from patients with AD is similar to that of normal human fibroblasts, However, when compared to human chemical-induced neuronal cells (hciNs) derived from healthy people, the extracellular Aβ42 level and the Aβ42/ Aβ40 ratio were higher in hciNs derived from fibroblasts derived from patients with familial Alzheimer's disease (FAD) carrying mutations in human amyloid precursor protein (APPV717I) [78].