In addition, the involvement of PSEN1 in multiple pathways regulating calcium homeostasis, Notch signaling, or beta-catenin stability, among others, causes PSEN1 mutations to impact other neurodegenerative but also non-neurodegenerative diseases [142,146], a fact that severely interfere with the design and development of new therapeutic avenues for AD based on PSEN1 level changes. The gene discussed is PSEN1; the disease is Alzheimer disease.