Human genetic studies have successfully identified single gene mutations in various neurodegenerative diseases, such as frontotemporal dementia (FTD), Parkinson's disease (PD), and Huntington's disease, which are associated with alterations in genes encoding Tau, α-synuclein, and protein Huntingtin, respectively (Ross and Poirier, 2004). The gene discussed is MAPT; the disease is frontotemporal dementia.