Biochemical and pathological characterization of frontotemporal dementia due to a Leu266Val mutation in microtubule-associated protein tau in an African American individual (original) (raw)
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American Journal of Human Genetics, 1999
Mutations in microtubule-associated protein tau recently have been identified in familial cases of frontotemporal dementia (FTD). We report the frequency of tau mutations in a large population-based study of FTD carried out in the Netherlands from January 1994 to June 1998. Thirty-seven patients had у1 first-degree relative with dementia. A mutation in the tau gene was found in 17.8% of the group of patients with FTD and in 43% of patients with FTD who also had a positive family history of FTD. Three distinct missense mutations (G272V, P301L, R406W) accounted for 15.6% of the mutations. These three missense mutations, and a single amino acid deletion (DK280) that was detected in one patient, strongly reduce the ability of tau to promote microtubule assembly. We also found an intronic mutation at position ϩ33 after exon 9, which is likely to affect the alternative splicing of tau. Tau mutations are responsible for a large proportion of familial FTD cases; however, there are also families with FTD in which no mutations in tau have been found, which indicates locus and/or allelic heterogeneity. The different tau mutations may result in disturbances in the interactions of the protein tau with microtubules, resulting in hyperphosphorylation of tau protein, assembly into filaments, and subsequent cell death.
Neurobiology of Aging, 2014
Microtubule-associated protein tau (MAPT) positive neuropathology is the characteristic feature of majority of frontotemporal dementia (FTD) cases, which is due to the mutations or haplotypic variations in the gene encoding MAPT (MAPT). The present study was aimed at determining the frequency of genetic variations in MAPT in a south Indian FTD cohort. The frequency of mutations were determined in 116 FTD, 8 progressive supranuclear palsy (PSP) and 3 corticobasal syndrome (CBS) patients and haplotype diversity were analyzed in a study cohort comprising 116 FTD, 8 PSP, 3 CBS, 194 other dementia groups, 78 mild cognitive impairment (MCI) and 130 cognitively normal individuals and report no pathogenic mutations in FTD/PSP/CBS or haplotypic association with disease risk in FTD or other dementia patients. These findings suggest that there may be other genetic or epigenetic factors contributing to the pathogenesis of FTD in the south Indian population.
Neurobiology of Aging, 2012
Microtubule-associated protein tau (MAPT) mutations have been shown to underlie frontotemporal dementia and a variety of additional sporadic tauopathies. 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. Two siblings of one patient also carried the p.A152T variant, and both have progressive cognitive impairment. Further screening identified the variant in two other cases: one with pathologically confirmed corticobasal degeneration and another with the diagnosis of Parkinson's disease with dementia. The balance of evidence suggests this variant is associated with disease, but the very varied phenotype of the cases with the mutation is not consistent with it being a fully penetrant pathogenic mutation. Interestingly, this variation results in the creation of a new phosphorylation site that could cause reduced microtubule binding. We suggest that the A152T variant is a risk factor associated with the development of atypical neurodegenerative conditions with abnormal tau accumulation.
Search for a Mutation in the tau Gene in a Swiss Family with Frontotemporal Dementia
Experimental Neurology, 2000
Frontotemporal dementia (FTD) is considered to have a heterogeneous aetiology. 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. The mutations reported so far are located within exons 9 to 13, a region coding for the microtubule-binding sites. They are causing various cytoskeletal disturbances. We are describing here the main clinical and neuropathological features of a Swiss FTD family with members presenting a FTDP-like clinical phenotype. However, if we except two silent polymorphic sites at position 227 and 255 in exon 9, neither a known FTDP-17 mutation nor a novel one was detected in this region of the tau gene. Thus, the existence of a yet unknown mechanism of neurodegeneration, other than via mutations near or within the microtubule-binding sites, or the exon 10 splice sites of the tau gene, has to be considered to explain dementia in this family. A mutation in another gene is still possible.
Novel G335V mutation in the tau gene associated with early onset familial frontotemporal dementia
Neurogenetics, 2005
Mutations in the tau gene cause familial frontotemporal dementia and parkinsonism linked to chromosome 17. Here we describe a novel missense mutation in exon 12 of the tau gene, G335V, in a German family with frontotemporal dementia of early age at onset, in the third decade of life. Functional analysis of recombinant tau protein with the G335V mutation showed a dramatically reduced ability to promote microtubule assembly and a more rapid and accelerated tau filament formation, suggesting that the primary effect of the mutation might be the provision of a pool of unbound tau making it available for aberrant tau aggregation.
Phenotypic variation in hereditary frontotemporal dementia with tau mutations
Annals of Neurology, 1999
Several mutations in the tau gene have been found in families with hereditary frontotemporal dementia and parkinsonism linked to chromosome 17q21-22 (FTDP-17). This study is the first attempt to correlate genotype and phenotype in six families with FTDP-17 with mutations in the tau gene (⌬K280, G272V, P301L, and R406W). We have investigated tau pathology in 1 P301L and 1 R406W patient. The R406W family showed a significantly higher age at onset (59.2 ؎ 5.5 years) and longer duration of illness (12.7 ؎ 1.5 years) than the families with the other mutations. The six families showed considerable variation in clinical presentation, but none of them had early parkinsonism. Mutism developed significantly later in the R406W family than in the other families. Frontotemporal atrophy on neuroimaging in the R406W family was less severe than in the P301L and ⌬K280 families. The P301L brain contained many pretangles in the frontal and temporal cortex, and the dentate gyrus of hippocampus, showing three tau bands (64, 68, and 72 kd) of extracted tau from the frontal cortex. The presence of many neurofibrillary tangles, many diffuse and classic neuritic plaques in the temporal and parietal cortex, and the hippocampus of the same P301L brain correlated with the presence of four sarkosyl-insoluble (60, 64, 68, and 72 kd) tau bands. The coexistence of characteristic P301L and Alzheimer pathology in the same brain needs further explanation. The R406W brain showed abundant neurofibrillary tangles in several brain regions, and four tau bands (60, 64, 68, and 72 kd) of extracted tau from these regions. The slower progression of the disease in the R406W family might be explained by the microtubule-binding properties of the mutant protein. van Swieten JC, Stevens M, Rosso SM, Rizzu P, Joosse M, de Koning I, Kamphorst W, Ravid R, Spillantini MG, Niermeijer MF, Heutink P. Phenotypic variation in hereditary frontotemporal dementia with tau mutations. Ann Neurol 1999;46:617-626 From the Departments of *Neurology and †Clinical Genetics, Erasmus University Rotterdam, Rotterdam; and ‡Department of Pathology, Vrije Universiteit, and §Dutch Brain Bank,
Tau is a candidate gene for chromosome 17 frontotemporal dementia
Annals of Neurology, 1998
Frontotempord dementia with parkinsonism, chromosome 17 type (FTDP-17), a recently defined disease entity, is clinically characterized by personality changes sometimes associated with psychosis, hyperorality, and diminished speech output, disturbed executive function and nonfluent aphasia, bradykinesia, and rigidity. Neuropathological changes include frontotemporal atrophy often associated with atrophy of the basal ganglia, substantia nigra, and amygdala. Neurofibrillary tangles (NFTs) are seen in some but not all families. Inheritance is autosomal dominant and the gene has been regionally localized to 17q21-22 in a 2to 4-centimorgan (cM) region flanked by markers D17S800 and D17S791. The gene for tau, the primary component of NFTs, is located in the same region of chromosome 17. Tau was evaluated as a candidate gene. Physical mapping studies place tau within 2 megabases or less of D17S791, but it is probably outside the D17S800-Dl7S791 FTDP-17 interval. DNA sequence analysis of tau coding regions in affected subjects from two FTDP-17 families revealed nine DNA sequence variants, eight of which were also identified in controls and are thus polymorphisms. A ninth variant (vd279Me1 was found in one FTDP-17 family but not in the second FTDP-17 family. Three lines of evidence indicate that the vd279Met change is an FTDP-17 causative mutation. First, the mutation site is highly conserved, and a normal valine is found at this position in all three tau interrepeat sequences and in other microtubule associated protein tau homologues. Second, the mutation co-segregates with the disease in family A. Third, the mutation is not found in normal controls.
BMC Neurology, 2009
The extended tau haplotype (H1) that covers the entire human microtubuleassociated protein tau (MAPT) gene has been implicated in Parkinson's disease (PD). Nevertheless, controversial results, such as two studies in Greek populations with opposite effects, have been reported. Therefore, we set out to determine whether the H1 haplotype and additional single nucleotide polymorphisms (SNPs) included in H1 are associated with PD in a sample of Greek patients.