Members of families with mutations in the tau gene are known to be heterogeneous in their clinical presentation, ranging from frontotemporal dementia to a clinical picture more resembling corticobasal degeneration or progressive supranuclear palsy.
The mechanism by which this common variability in the tau gene influences the development of PSP is unclear; however, it further suggests a central role for tau in the pathogenesis of several neurodegenerative conditions including Alzheimer's disease (AD).
Tauopathies, characterized by the dysfunction and aggregation of the microtubule-associated protein tau (MAPT), represent some of the most devastating neurodegenerative disorders afflicting the elderly, including Alzheimer's disease and progressive supranuclear palsy.
They include the largely sporadic Alzheimer's disease, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), Pick's disease (PiD), argyrophilic grain disease, as well as the inherited frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17).
Tauopathies are a class of neurodegenerative diseases, including Alzheimer's disease, frontotemporal dementia and progressive supranuclear palsy, which are associated with the pathological aggregation of tau protein into neurofibrillary tangles (NFT).
Common and rare variants in the MAPT gene increase the risk for sporadic FTLD-Tau, including progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD).
This study demonstrates that 22 unrelated progressive supranuclear palsy (PSP) patients have four identical sequence variants within the tau gene that are not present in 24 age-matched controls.
However, we found a strong association of two H1 sub-haplotypes with PSP and CBD (H1E'C and H1Q), which include MAPT and CRHR1 genes where the risk variant for PSP/CBD could lie.
Characteristic tau isoform composition of the insoluble fibrillar tau inclusions define tauopathies, including Alzheimer's disease (AD), progressive supranuclear palsy (PSP) and frontotemporal dementia with parkinsonism linked to chromosome 17/frontotemporal lobar degeneration-tau (FTDP-17/FTLD-tau).
Strong genetic evidences for the involvement of the tau gene variability in the pathogenesis of PSP have been demonstrated in several Caucasian populations.
These results are consistent with the hypothesis that a change either in the 5' or in the 3' flanking regions of the tau gene, or even other genes contained in the H1E haplotype, could increase the genetic susceptibility to PSP.
In addition to the tau mutations, a common extended haplotype in the tau gene also appears to be a risk factor in the development of the apparently sporadic tauopathies progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD).
We show that the entire, fully extended H1 haplotype is associated with PSP, which implicates several other genes in addition to MAPT, as candidate pathogenic loci.
Linkage disequilibrium fine mapping and haplotype association analysis of the tau gene in progressive supranuclear palsy and corticobasal degeneration.
Using 15 haplotype tagging SNPs (htSNPs), capturing >95% of MAPT haplotype diversity, we performed association analysis in a US sample of 274 predominantly pathologically confirmed PSP patients and 424 matched control individuals.
Abnormal tau inclusions, in selected regions of the brain, are a hallmark of the disease and the H1 haplotype of MAPT, the gene encoding tau, is the major risk factor in PSP.
Mutations in the tau gene, MAPT, cause familial frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), and common variation in MAPT is strongly associated with the risk of PSP, corticobasal degeneration and, to a lesser extent, AD and Parkinson's disease (PD), implicating the involvement of tau in common neurodegenerative pathway(s).