Some aspects of this disclosure provide strategies, systems, reagents, methods, and kits that are useful for the targeted editing of nucleic acids, including editing a nucleic acid encoding a mutant Presenilin1 protein to correct a point mutation associated with a disease or disorder, e.g., with familial Alzheimer's disease. The methods provided are useful for correcting a PSEN1 point mutation within the genome of a cell or subject, e.g., within the human genome. In some embodiments, fusion proteins of Cas9 and nucleic acid editing enzymes or enzyme domains, e.g., deaminase domains, are provided. In some embodiments, reagents and kits for the generation of targeted nucleic acid editing proteins, e.g., fusion proteins of Cas9 and nucleic acid editing enzymes or domains, are provided.