Journal of Alzheimer's disease : JAD
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The frequency and clinical and pathological characteristics associated with the Gly206Ala presenilin 1 (PSEN1) mutation in Puerto Rican and non-Puerto Rican Hispanics were evaluated at the University of Pennsylvania's Alzheimer's Disease Center. DNAs from all cohort subjects were genotyped for the Gly206Ala PSEN1 mutation. Carriers and non-carriers with neurodegenerative disease dementias were compared for demographic, clinical, psychometric, and biomarker variables. ⋯ Neuropathological examination in one subject revealed severe, widespread plaque and tangle pathology without other meaningful disease lesions. The PSEN1 Gly206Ala mutation is notably frequent in unrelated Puerto Rican immigrants with dementia in Philadelphia. Considered together with the increased prevalence and mortality of AD reported in Puerto Rico, these high rates may reflect hereditary risk concentrated in the island which warrants further study.
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Case Reports
Novel missense progranulin gene mutation associated with the semantic variant of primary progressive aphasia.
Progranulin (GRN) mutations are typically associated with the behavioral variant of frontotemporal dementia and the non-fluent variant of primary progressive aphasia phenotypes. Hereby, we describe a patient affected by semantic variant of primary progressive aphasia (svPPA) with a highly positive family history of dementia, carrying a novel GRN missense variation in exon 11 [g.2897 C > T (p. ⋯ The variant was absent in 175 frontotemporal lobar degeneration (FTLD) patients and in 38 healthy subjects. This case confirms that GRN represents one of the most frequent FTLD genetic causes, suggesting that a screening is indicated in the case of svPPA presentation.
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The aim of our study was to elucidate whether specific patterns of gray matter loss were associated with apolipoprotein E ε4 (APOE ε4) and microtubule-associated protein tau (MAPT)-H1) genetic variants in subjects with mild cognitive impairment (MCI) at a baseline visit. Gray matter voxel-based morphometry analysis of T1 magnetic resonance imaging scans were performed in 65 amnestic-MCI subjects. MCI APOE ε4 carriers compared with non-carriers showed increased brain atrophy in right hippocampus and rostral amygdala, superior and middle temporal gyrus, and right parietal operculum, including inferior frontal gyrus, inferior parietal, and supramarginal gyrus. ⋯ The pattern of frontal gray matter loss observed among MCI MAPT H1/H1 carriers has also been found in other tauopathies, suggesting that MCI may share etiological factors with other tauopathies. Frontal and parietal cortex vulnerability was found when adding MAPT H1/H1 and APOE ε4 effects, suggesting a synergistic effect of these variants. These results could be due to changes in APOE ε4 and MAPT expression.
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The rs75932628-T variant of the gene encoding the triggering receptor expressed on myeloid cells 2 (TREM2) has recently been identified as a rare risk factor for late-onset Alzheimer's disease (AD). In this study we examined the association between TREM2 exon 2 variants and early-onset AD in a sample of Caucasian subjects of French origin including 726 patients with age of onset ≤65 years and 783 controls. Only the rs75932628-T variant (predicted to cause an R47H substitution) conferred a significant risk for early-onset AD (OR, 4.07; 95% CI, 1.3 to 16.9; p = 0.009). These results confirm the association between this variant and AD and underline its involvement in early-onset cases.
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Mild traumatic brain injury (mTBI) is considered the 'signature injury' of combat veterans that have served during the wars in Iraq and Afghanistan. This prevalence of mTBI is due in part to the common exposure to high explosive blasts in combat zones. In addition to the threats of blunt impact trauma caused by flying objects and the head itself being propelled against objects, the primary blast overpressure (BOP) generated by high explosives is capable of injuring the brain. ⋯ In hippocampus, aberrant tau species persisted for at least 30 days post-exposure, while SOD2 levels returned to sham control levels. These findings suggest that elevated phospho- and cleaved-tau species may be among the initiating pathologic processes induced by mild blast exposure. These findings may have important implications for efforts to prevent blast-induced insults to the brain from progressing into long-term neurodegenerative disease processes.