MAPT and Alzheimer disease: More than 40 MAPT gene variants are known, including variants with mutations, insertions, deletions, etc. The abnormal aggregation of tau protein has been associated with a variety of neurodegenerative diseases, such as AD, FTD, and corticobasal ganglionic degeneration, and mutations in the MAPT gene are thought to be an important cause; thus, the MAPT gene has significance for the study of neurodegenerative diseases [123].