MAPT and semantic dementia: In addition, several specific mutations in the tau gene associated with frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) lead to dysregulation of tau E10 splicing and result in a selective increase in either 3R-tau or 4R-tau, which is also related to other neurodegenerative disorders, such as FTD and FTDP-17.