Biomedical subjects
Publications and source records attributed to D Dickson.
We have assessed whether apolipoprotein E (ApoE) genotype influences the age of onset of dementia in a series of families with frontal temporal dementia with defined mutations in the tau gene. In contrast to the situation in Alzheimer's disease (AD), we could find no evidence that the age of onset of disease was influenced by the ApoE genotype.
Splice-site and missense mutations have been identified in tau associated with frontotemporal dementia with parkinsonism linked to chromosome 17. In this study we assessed the genetic contribution of tau mutations to three patient series with non-Alzheimer's (non-AD) degenerative dementia. The groups included (1) a community-based dementia series from Minnesota, MN; (2) a referral series with clinicopathological tauopathy; and (3) a pathologically confirmed familial frontotemporal dementia series from Manchester, UK. Comparing the three clinical series: in the stringently diagnosed Manchester frontotemporal dementia series, tau mutations were present in 13.6% of cases (three splice-site mutations); in the clinicopathological referral series that used more general inclusion criteria, 3 cases with P301L mutations were observed, which represents a lower mutation frequency of 3.6% (9.4% in familial cases); in contrast, tau mutations were not detected in the Minnesota community-based dementia series, suggesting the occurrence of these mutations in dementia generally is rare (<0.2%). These data identify the prevalence of mutations in three different clinical settings and indicate that this figure is sensitive to the diagnostic criteria used in each patient series.
Doubly transgenic mice (PSAPP) overexpressing mutant APP and PS1 transgenes were examined using antibodies to Abeta subtypes and glial fibrillary acidic protein (GFAP). Visible Abeta deposition began primarily in the cingulate cortex of PSAPP mice at approximately 10 weeks of age. By 6 months, the mice had extensive amyloid deposition throughout the hippocampus and cortex as well as other regions of the brain. Highly congophilic deposits consisting of N-terminal normal and modified forms of Abeta were identified, reminiscent of those found in human AD brain. Both immunohistochemistry and mass spectrometry showed that Abeta42 forms were underrepresented relative to Abeta40, and Abeta43 was undetectable. Deposits were associated with prominent gliosis which increased with age, but in 14-month-old PSAPP mice, GFAP immunoreactivity in the vicinity of amyloid deposits was substantially reduced compared to APP littermates. These mice have considerable utility in the study of the amyloid phenotype of AD.
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We describe two extended haplotypes that cover the human tau gene. In a total of approximately 200 unrelated caucasian individuals there is complete disequilibrium between polymorphisms which span the gene (which covers approximately 100 kb of DNA). This suggests that the establishment of the two haplotypes was an ancient event and either that recombination is suppressed in this region, or that recombinant genes are selected against. Furthermore, we show that the more common haplotype (H1) is significantly over-represented in patients with progressive supranuclear palsy (PSP), extending earlier reports of an association between an intronic dinucleotide polymorphism and PSP.
A 12-year-old boy under treatment for asthma was found dead in his home. The autopsy revealed a large posterior mediastinal mass that completely compressed the upper lobe of the right lung and the associated airways. This mass extended from the right costovertebral sulcus into the thoracic spinal canal through the spinal foramen and compressed the spinal cord. It was located in the epidural space and was adherent to a nerve root. The histologic and immunocytochemical features were that of a paraganglioma. Although neurogenic tumors are the most common posterior mediastinal masses in the pediatric population, paragangliomas are rare, and spinal involvement has not been described in children. In addition, sudden death has not been reported in association with any of the 13 cases of posterior mediastinal paraganglioma described in the literature as involving the spine. This case illustrates an unusual cause of sudden death in a pediatric patient due to a benign neoplasm.
OBJECTIVE: To evaluate the sensitivity and specificity of the clinical features of three published diagnostic criteria for diffuse Lewy body disease (DLBD) using autopsy-confirmed Alzheimer's (AD), DLBD and AD+DLBD (mixed) dementia cases. DESIGN: Retrospective chart review of an autopsy series of 56 patients selected from the State of Florida Brain Bank on the basis of a pathological diagnosis of either pure AD, DLBD (pure and common forms) or AD+DLBD (mixed) dementia. Clinical features were assessed by three raters blind to the pathological diagnosis. RESULTS: The existing criteria for a clinical diagnosis of DLBD were highly specific (90-100%) but not very sensitive (49-63%) in the differential diagnosis of DLBD versus AD; sensitivity did improve (61-74%) when mixed AD+DLBD cases were eliminated. Clinical features that occur more frequently in DLBD than in AD were unspecified hallucinations, unspecified EPS, fluctuating course and rapid progression. Post-hoc analysis also indicated that hallucinations and EPS were more common early in the disease course of DLBD than in AD. Empirically derived criteria, formulated using the most prevalent clinical features, demonstrated sensitivity values of 57-96% for pure forms and 43-91% for mixed forms. CONCLUSIONS: This study demonstrated that additional improvements in the established criteria for DLBD are needed. Our empirically derived criteria enhanced the distinction of DLBD from AD while allowing the clinician the choice of maximizing sensitivity with acceptable specificity, and vice versa.
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Thirteen families have been described with an autosomal dominantly inherited dementia named frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), historically termed Pick's disease. Most FTDP-17 cases show neuronal and/or glial inclusions that stain positively with antibodies raised against the microtubule-associated protein Tau, although the Tau pathology varies considerably in both its quantity (or severity) and characteristics. Previous studies have mapped the FTDP-17 locus to a 2-centimorgan region on chromosome 17q21.11; the tau gene also lies within this region. We have now sequenced tau in FTDP-17 families and identified three missense mutations (G272V, P301L and R406W) and three mutations in the 5' splice site of exon 10. The splice-site mutations all destabilize a potential stem-loop structure which is probably involved in regulating the alternative splicing of exon10. This causes more frequent usage of the 5' splice site and an increased proportion of tau transcripts that include exon 10. The increase in exon 10+ messenger RNA will increase the proportion of Tau containing four microtubule-binding repeats, which is consistent with the neuropathology described in several families with FTDP-17.
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