Frontotemporal dementia and parkinsonism linked to chromosome 17.

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is an autosomal dominant neurodegenerative disorder caused by mutations in the MAPT gene which encodes the microtubule-associated protein tau. This hereditary tauopathy is a rare clinical syndrome, affecting approximately two hundred kindreds and about six hundred individuals bearing thirty nine known MAPT mutations. The disorder is thought to be related to the altered proportion of tau protein isoforms or the ability of tau to bind to microtubules and to promote microtubule assembly and organization. The clinical presentation of FTDP-17 includes behavioral, cognitive and motor abnormalities. This disorder has both a variable course and phenotype. Gross neuropathological examination reveals brain atrophy, especially of the frontal and temporal lobes, and selective atrophy of the basal ganglia and brainstem nuclei. The major microscopic features of FTDP-17 demonstrate the presence of neurofibrillary tangles, neuropil threads and glial inclusions composed of insoluble tau protein. Distribution and amount of tau deposits vary, depending on the type of MAPT mutation. The definitive diagnosis of FTDP-17 requires a set of clinical and pathological features combined with a molecular genetic analysis. Currently, there is no known effective treatment for FTDP-17.