Parkinsonism and distinct dementia patterns in a family with the MAPT R406W mutation.

The Arg406Trp (R406W) missense mutation in the microtubule-associated protein-tau gene (MAPT) is a known cause of early-onset dementia. Various dementia phenotypes have been described, including frontotemporal dementia (FTD), FTD with parkinsonism, and early-onset Alzheimer disease (EOAD)-like presentations.