[<sup>11</sup> C]PBB3-PET can capture four-repeat tau pathologies characteristic of N279K mutant frontotemporal dementia and parkinsonism linked to chromosome 17/MAPT.
We identified a rare p.A152T variant in MAPT exon 7 in two (of eight) patients with clinical presentation of parkinsonism and postmortem finding of neurofibrillary tangle pathology.
We have previously generated a double transgenic mouse line overexpressing the enzyme GSK-3beta and tau protein carrying a triple frontotemporal dementia and parkinsonism linked to chromosome 17 mutation whose expression patterns overlap in CA1 (pyramidal neurons) and dentate gyrus (granular neurons).
Variants of the MAPT gene have been suggested to be associated with Parkinson's disease (PD) and to modify the risk for leucine-rich repeat kinase 2 (LRRK2) Parkinsonism.
To date the tau gene located on chromosome 17 has been shown to be implicated in the pathogenesis of several FTD families with parkinsonism, the so called FTDP-17 families.
These mice contain a tau gene with a mutation of the frontotemporal dementia parkinsonism (FTDP-17) type, in which valine is substituted with methionine residue 337.
These findings suggest that tau proteins are not always assembled in abnormal filaments such as twisted ribbons, paired helical filaments and straight tubules in neurons and glial cells, which have been shown in previous cases with frontotemporal dementia and parkinsonism linked to chromosome 17.
The second part will deal with the recent discovery of tau gene mutations in frontotemporal dementia and parkinsonism linked to chromosome 17 which demonstrates that tau dysfunction can lead to neurodegeneration.
The role of tau in neurodegeneration has been clarified by the identification of genetic mutations in the tau gene in cases with familial frontotemporal dementia and parkinsonism linked to chromosome 17.
The recent discovery of tau gene mutations in FTD with Parkinsonism linked to chromosome 17 has reinforced the direct role attributed to abnormal tau proteins (hyperphosphorylation) and thus raised the possibility to target specifically these processes by drugs (aetiopathogenic compounds).
The MAPT gene, located on 17q21 and coding for the human microtubule-associated protein tau, is a strong candidate gene, since tau-positive neuronal inclusions have been observed in brains from some FTDP patients.
The identification of mutations in MAPT, the gene that encodes tau, causing dementia and parkinsonism established the notion that tau aggregation is responsible for the development of disease.
The frontotemporal dementia (FTD) syndromes have been associated with the microtubule-associated tau protein since tau gene mutations have been demonstrated to be the cause of FTD and parkinsonism linked to chromosome 17.
The first mutations associated with frontotemporal lobar degeneration (FTLD) were found in the microtubule-associated protein tau (MAPT) gene on chromosome 17 in families with frontotemporal degeneration and parkinsonism (FTDP-17).
The discovery of multiple tau gene mutations that are pathogenic for hereditary frontotemporal dementia and parkinsonism linked to chromosome 17 in many kindreds, as well as the demonstration that tau polymorphisms are genetic risk factors for sporadic tauopathies, directly implicate tau abnormalities in the onset/progression of neurodegenerative disease.
The assembly of tau protein into abnormal filaments and brain cell degeneration are characteristic of a number of human neurodegenerative diseases, including Alzheimer's disease and frontotemporal dementia and parkinsonism linked to chromosome 17.
The analysis of tau gene and the study of familial cases of tauopathies have led to the discovery of tau gene mutations that cause inherited dementia designated as Frontotemporal dementia (FTD) with parkinsonism linked to chromosome 17 (FTDP-17).
The aggregation of NFTs, the abnormal hyperphosphorylation of tau protein, and the interaction between tau and alpha-synuclein may all contribute to the cell death and poor axonal transport observed in PD and Parkinsonism.
The MAPT gene has been shown to be associated with several neurodegenerative disorders, including forms of parkinsonism and Parkinson disease (PD), but the results reveal population differences.
Tauopathies with parkinsonism represent a spectrum of disease entities unified by the pathologic accumulation of hyperphosphorylated tau protein fragments within the central nervous system.