1/2. Classic Pick's disease type with ubiquitin-positive and tau-negative inclusions: case report.We report on a patient presenting Pick's disease similar to the one reported by Pick in 1892, with ubiquitin-positive and tau-negative inclusions. His diagnosis was made on the basis of clinical (language disturbance and behavioural disorders), neuropsychological (progressive aphasia of the expression type and late mutism), neuroimaging with magnetic resonance (bilateral frontal and temporal lobes atrophy) and brain single photon emission computed tomography (frontal and temporal lobes hypoperfusion) studies. Macroscopic examination showed atrophy on the frontal and temporal lobes. The left hippocampus displayed a major circumscribed atrophy. The diagnostic confirmation was made by the neuropathological findings of the autopsy that showed neuronal loss with gliosis of the adjacent white matter and apearance of status spongiosus in the middle frontal and especially in the upper temporal lobes. There were also neuronal swelling (ballooned cell) and argyrophilic inclusions (Pick's bodies) in the left and right hippocampi. Anti-ubiquitin reaction tested positive and anti-tau tested negative.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
2/2. frontotemporal dementia with Pick-type histology associated with Q336R mutation in the tau gene.In this report, we describe the clinical and neuropathological features of a case of familial frontotemporal dementia (FTD), with onset at 58 years of age and disease duration of 10 years, associated with a novel mutation, Q336R, in the tau gene (tau). in vitro studies concerning the properties of tau proteins bearing this mutation, with respect to microtubule assembly and tau filament aggregation, are reported. Clinically, the patient showed alterations in memory, language and executive functions and marked behavioural change consistent with FTD, although the extent of memory impairment was more than is characteristic of FTD. At autopsy, there was degeneration of the frontal and temporal lobes associated with the presence of hyperphosphorylated tau proteins in swollen (Pick) cells and intraneuronal inclusions (Pick bodies). By immunohistochemistry, the Pick bodies contained both 3-repeat and 4-repeat tau proteins although, because no fresh tissues were available for analysis, the exact isoform composition of the aggregated tau proteins could not be determined. neurons within frontal cortex contained neurofibrillary tangle-like structures, comprising both straight and twisted tubules, or Pick bodies in which the filaments were short and randomly orientated. in vitro, and in common with other tau missense mutations, Q336R caused an increase in tau fibrillogenesis. However, in contrast to most other tau missense mutations, Q336R increased, not decreased, the ability of mutant tau to promote microtubule assembly. Nonetheless, this latter functional change may likewise be detrimental to neuronal function by inducing a compensatory phosphorylation that may yield increased intracellular hyperphosphorylated tau species that are also liable to fibrillize. We believe the mutation is indeed pathogenic and disease causing and not simply a coincidental rare and benign polymorphism. Since this mutation is segregating with the FTD clinical and neuropathological phenotype, it has not been found in unaffected individuals and it has novel functional properties in vitro which are likely to be detrimental to neuronal function in vivo.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |