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A study published in the journal Brain Pathology explores the use of poly-GA immunohistochemistry as a reliable tool for detecting C9orf72 hexanucleotide repeat expansions, which are associated with neurodegenerative diseases. The study found that poly-GA immunohistochemistry accurately identified neuronal cytoplasmic inclusions and neurites in cases with known C9orf72 repeat expansion. This method is particularly useful in research settings where genetic testing has not been performed or suitable tissue is not available post-mortem. The study highlights the potential of poly-GA immunohistochemistry as an economical and sensitive alternative to genetic testing for detecting C9orf72 repeat expansions. [Extracted from the article]

Objectives: Abnormal beliefs and delusions have been reported in some people with dementia, however, the prevalence of delusions, and their neurocognitive basis has been underexplored. This study aimed to examine the presence, severity, content and neural correlates of delusions in a large, well-characterised cohort of dementia patients using a transdiagnostic, cross-sectional approach.Methods: Four-hundred and eighty-seven people with dementia were recruited: 102 Alzheimer's disease, 136 behavioural-variant frontotemporal dementia, 154 primary progressive aphasia, 29 motor neurone disease, 46 corticobasal syndrome, 20 progressive supranuclear palsy. All patients underwent neuropsychological assessment and brain magnetic resonance imaging, and the Neuropsychiatric Inventory was conducted with an informant, by an experienced clinician.Results: In our cohort, 48/487 patients (10.8%) had delusions. A diagnosis of behavioural-variant frontotemporal dementia (18.4%) and Alzheimer's disease (11.8%) were associated with increased risk of delusions. A positive gene mutation was observed in 11/27 people with delusions. Individuals with frequent delusions performed worse on the Addenbrooke's Cognitive Examination (p = 0.035), particularly on the orientation/attention (p = 0.022) and memory (p = 0.013) subtests. Voxel-based morphometry analyses found that increased delusional psychopathology was associated with reduced integrity of the right middle frontal gyrus, right planum temporale and left anterior temporal pole.Conclusion: Our results demonstrate that delusions are relatively common in dementia and uncover a unique cognitive and neural profile associated with the manifestation of delusions. Clinically, delusions may lead to delayed or misdiagnosis. Our results shed light on how to identify individuals at risk of neuropsychiatric features of dementia, a crucial first step to enable targeted symptom management. [ABSTRACT FROM AUTHOR]

ABSTRACT Parkinson's disease (PD) is a neurodegenerative disorder for which environmental factors influence disease risk and may act via an epigenetic mechanism. The microtubule-associated protein tau ( MAPT) is a susceptibility gene for idiopathic PD. Methylation levels were determined by pyrosequencing of bisulfite-treated DNA in a leukocyte cohort (358 PD patients and 1084 controls) and in two brain cohorts (Brain1, comprising 69 cerebellum controls; and Brain2, comprising 3 brain regions from 28 PD patients and 12 controls). In vitro assays involved the transfection of methylated promoter-luciferase constructs or treatment with an exogenous micronutrient. In normal leukocytes, the MAPT H1/H2 diplotype and sex were predictors of MAPT methylation. Haplotype-specific pyrosequencing confirmed that the H1 haplotype had higher methylation than the H2 haplotype in normal leukocytes and brain tissues. MAPT methylation was negatively associated with MAPT expression in the Brain1 cohort and in transfected cells. Methylation levels differed between three normal brain regions (Brain2 cohort, putamen < cerebellum < anterior cingulate cortex). In PD samples, age at onset was positively associated with MAPT methylation in leukocytes. Moreover, there was hypermethylation in the cerebellum and hypomethylation in the putamen of PD patients compared with controls (Brain2 cohort). Finally, leukocyte methylation status was positively associated with blood vitamin E levels, and the effect was more significant in H2 haplotype carriers; this result was confirmed in cells that were exposed to 100 μM vitamin E. The significant effects of sex, diplotype, and brain region suggest that hypermethylation of the MAPT gene is neuroprotective by reducing MAPT expression. The effect of vitamin E on MAPT represents a possible gene-environment interaction. © 2013 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Objective: Frontotemporal lobar degeneration (FTLD) is the most common cause of early-onset dementia. Pathological ubiquitinated inclusion bodies observed in FTLD and motor neuron disease (MND) comprise trans-activating response element (TAR) DNA binding protein (TDP-43) and/or fused in sarcoma (FUS) protein. Our objective was to identify the causative gene in an FTLD-MND pedigree with no mutations in known dementia genes. Methods: A mutation screen of candidate genes, luciferase assays, and quantitative polymerase chain reaction (PCR) was performed to identify the biological role of the putative mutation. Neuropathological characterization of affected individuals and western blot studies of cell lines were performed to identify the pathological mechanism of the mutation. Results: We identified a nonpolymorphic mutation (c.672*51G>T) in the 3′-untranslated region (UTR) of the Sigma nonopioid intracellular receptor 1 ( SIGMAR1) gene in affected individuals from the FTLD-MND pedigree. The c.672*51G>T mutation increased gene expression by 1.4-fold, corresponding with a significant 1.5-fold to 2-fold change in the SIGMAR1 transcript or Sigma-1 protein in lymphocyte or brain tissue. Brains of SIGMAR1 mutation carriers displayed a unique pathology with cytoplasmic inclusions immunopositive for either TDP-43 or FUS but not Sigma-1. Overexpression of SIGMAR1 shunted TDP-43 and FUS from the nucleus to the cytoplasm by 2.3-fold and 5.2-fold, respectively. Treatment of cells with Sigma-1 ligands significantly altered translocation of TDP-43 by up to 2-fold. Interpretation: SIGMAR1 is a causative gene for familial FTLD-MND with a unique neuropathology that differs from other FTLD and MND cases. Our findings also suggest Sigma-1 drugs as potential treatments for the TDP-43/FUS proteinopathies. Ann Neurol 2010;68:639-649 [ABSTRACT FROM AUTHOR]

Background: The risk for mental illnesses such as depression is increasingly conceptualized as the product of gene–environment interactions and their impact on brain structure and function. The role of serotonin 3A receptor gene (HTR3A -42C>T polymorphism) and its interaction with early life stress (ELS) was investigated in view of the receptor's localization to brain regions central to emotion processing. Methods: Fronto-limbic grey matter (GM) loss was measured using magnetic resonance imaging and assessed using voxel-based morphometry analysis in 397 nonclinical individuals from the Brain Resource International Database. Negative mood symptoms were also assessed. Results: The HTR3A CC genotype group, compared to the T carriers, demonstrated comparative loss to GM in hippocampal structures, which extended to the frontal cortices for those CC genotype individuals also exposed to ELS. Elevations in depressed mood were also evident. Conclusions: These findings suggest that the HTR3A CC genotype may be associated with alterations in brain structures central to emotion processing, particularly when exposed to stress, and further highlight the potential role of the serotonin system in the pathophysiology of affective disorders. In contrast, those individuals with the T allele, in particular the TT genotype, may be more protected from such alterations combined with minimal exposure to ELS events. Depression and Anxiety, 2010. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Altered hippocampal volume, the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism, and neuroticism have each been implicated in the etiology of psychiatric disorders, especially depression. However, the relationship between these variables is not well understood. Here, we determined the effects of the BDNF Val66met polymorphism on the five-factor personality dimensions (assessed using the NEO-FFI), trait depression (assessed with the DASS-21) in a cross-sectional cohort of 467 healthy volunteers. A large matched subset of this cohort was also assessed for grey matter volume of the hippocampus and contiguous temporal cortical regions using magnetic resonance imaging. In Met carriers, elevations in neuroticism and trait depression and stress were associated with lower mean hippocampal volume, but there were no such associations in Val homozygotes. Trait depression, in particular, was found to moderate the effects of BDNF genotypes on hippocampal volume. Met carriers with high trait depression showed a reduction in grey matter volume of the mean hippocampus compared with Val homozygotes. These findings suggest that even in otherwise healthy subjects, trait depression may contribute to the susceptibility of Met carriers to hippocampal grey matter loss. Hum Brain Mapp 2009. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Background: Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are clinically and pathologically overlapping disorders with shared genetic causes. We previously identified a disease locus on chromosome 16p12.1‐16q12.2 for a large European Australian family with FTD‐ALS [Dobson‐Stone et al 2013, Acta Neuropathol 125:523‐533]. We have recently identified the p.M719V substitution in CYLD as the causal mutation at this locus. CYLD is a lysine‐63 deubiquitinase and CYLDM719V shows significantly increased deubiquitinase activity [Dobson‐Stone et al, Brain, accepted Dec 2019]. We sought to determine what biological pathways are affected by the presence of this mutation. Method: We performed label‐free mass spectrometry quantitative proteomic analysis of HEK293 lysates overexpressing wild‐type (CYLDwt), FTD‐ALS mutant CYLDM719V or deubiquitinase‐inactive mutant CYLDD681G. We used Ingenuity Pathway Analysis to predict dysregulated biological pathways. We examined necroptosis in L929 cells overexpressing CYLDwt and CYLDM719V, measuring cell viability (ATP production) and cell death (membrane permeabilisation). Result: 276 proteins exhibited significantly altered expression when CYLDM719V was overexpressed, relative to CYLDwt. Pathway analysis predicted activation of apoptosis with CYLDM719V. This is likely related to deubiquitinase activity, as CYLDD681G was predicted to have the opposite effect. We are working to validate these findings by immunoblot and co‐immunoprecipitation analyses. CYLD has recently been identified as a mediator of another cell death pathway, necroptosis. We found a small but significant effect of CYLDM719V on cell viability after treatment with necroptosis inducer Z‐VAD‐FMK in L929 cells at 0.2 μM (8.8% decrease relative to control, Student's t test p = 0.006), 2 μM (26.1% decrease, p = 0.0003) and 20 μM (38.6% decrease, p = 0.00005). CYLDwt showed significant effects only at higher doses (0.2 μM: 1.1% decrease, p = 0.396; 2 μM: 10.8% decrease, p = 0.049; 20 μM: 32.5% decrease, p = 0.0001). Conclusion: Our study indicates that CYLDM719V may act in part by inappropriate activation of apoptosis and/or necroptosis, possibly via sensitising CYLD's response to death stimuli. It remains to be seen which of these mechanisms is critical to CYLD's effects on neurodegeneration in FTD and ALS, although our data lend support to the emerging research showing necroptosis as a plausible therapeutic target for ALS. [ABSTRACT FROM AUTHOR]

As with other neurodegenerative disorders, research into the group of diseases known under the umbrella term of "neuroacanthocytosis" has greatly benefited from the identification of causative genes. The distinct and unifying aspect of these disorders is the presence of thorny deformations of circulating erythrocytes. This may be due to abnormal properties of red cell membranes, which could lead to insights into mechanisms of neurodegeneration. Research approaches in this field, in addition to examining functions and protein interactions of the affected proteins with particular respect to neurons, have also drawn upon the expertise of hematologists and red cell membrane biologists. In this article, recent developments in the field are presented. [ABSTRACT FROM AUTHOR]

Purpose: Choreoacanthocytosis (ChAc) is an autosomal recessive disorder caused by mutations in VPS13A on chromosome 9q21 and characterized by neurodegeneration and red cell acanthocytosis. Seizures are not uncommon in ChAc but have not been well characterized in the literature. We report two ChAc families in which patients presented with temporal lobe epilepsy. Methods: Detailed medical and family histories were obtained. EEG, video-telemetry, brain magnetic resonance imaging (MRI) with volumetric studies of amygdala and hippocampus, as well as neuropsychological testing were performed. Blood smears were examined for acanthocytosis. Mutation analysis of VPS13A was carried out in five patients. Results: Six patients in three sibships were initially seen with seizures. Age at seizure onset ranged from 22 to 38 years. Seizures preceded other clinical manifestations of ChAc by ≤15 years. The epileptic aura consisted of a sensation of déjà-vu, fear, hallucinations, palpitations, or vertigo. EEG with video-telemetry showed epileptiform discharges originating either from one or both temporal lobes. Epilepsy was generally well controlled, but some patients had periods of increased seizure frequency requiring treatment with multiple antiepileptic drugs (AEDs). Both families shared a deletion of exons 70–73 of VPS13A, extending to exons 6–7 of GNA14. Conclusions: Temporal lobe epilepsy may be the presenting feature of ChAc and may delay its diagnosis. Epilepsy in ChAc patients represents a challenge, because seizures may at times be difficult to control, and some AEDs may worsen the involuntary movements. Mutations in VPS13A or GNA14 or both may be associated with clinical features of temporal lobe epilepsy. [ABSTRACT FROM AUTHOR]

Chorea-acanthocytosis is a rare autosomal recessive disorder. Its characteristics are orofacial dyskinesia, hyporeflexia, seizures, aberrant behavior, atrophy of the caudate and putamen, and acanthocytes in the blood with a normal level of lipoproteins. We describe three families with chorea-acanthocytosis. The inheritance pattern was recessive and the average age at onset was 27 years (range, 18-35 years). The presenting symptoms were seizures, aberrant behaviour, chorea, tics, and/or abnormal gait. Phase-contrast and electron microscopy examinations of blood showed 10 to 40% acanthocytes. The lipid profile was normal except that, in one family, no prebetalipoprotein bands corresponding to the fraction of very low-density lipoprotein were seen in high-resolution lipoprotein electrophoresis. Magnetic resonance imaging of the brain showed marked atrophy in the caudate and putamen; 18-fluorodeoxyglucose positron emission tomography scan showed hypometabolism in the striatum. In all three families, the disease was linked to a 6-cM region of chromosome 9q21 flanked by the recombinant markers GATA 89a11 and D9S1843. This finding strongly suggests the involvement of a single locus for this syndrome. Three different homozygous mutations of this gene have been identified. Although the clinical presentation was variable, the genetic studies on these three Saudi Arabian families with chorea-acanthocytosis provide strong evidence for a genetic locus for chorea-acanthocytosis at chromosome 9q21. © 2002 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Background: Identified genetic mutations account for ∼50% of familial frontotemporal dementia (FTD) and ∼70% of familial amyotrophic lateral sclerosis (ALS) cases, however, for the remainder of patients the origin of the disease is uncertain. Post‐mortem, affected neurons from 97% of ALS and ∼50% of FTD patients show cytoplasmic mislocalisation of the typically nuclear proteins, TDP‐43 and/or FUS. We exploited this predominant neuropathological feature to develop a high‐throughput, automated method for the quantification of cytoplasmic TDP‐43 and FUS in human cell lines. Method: Utilising fluorescently tagged cDNA constructs to identify cells of interest, fluorescence intensity of TDP‐43 or FUS in the nucleus and cytoplasm of HEK293 and SH‐SY5Y cells was measured from confocal microscope images using the freely available analysis software, CellProfiler. The assay was validated using known ALS‐causative mutations in the genes encoding TDP‐43 (TARDBP) and FUS, and pharmacological interventions known to cause TDP‐43 and FUS mislocalisation. The ability of the assay to detect effects of a secondary gene on endogenous TDP‐43 was tested using CYLD wild‐type and mutant constructs. Results: Expression of known TARDBP and FUS mutations showed significantly higher cytoplasmic to nuclear ratios when compared to wild‐type protein. Treatment with apoptosis inducers MG132 and staurosporine induced a similar effect. Lastly, we recapitulated the effect of the CYLD FTD‐ALS mutation p.M719V on TDP‐43 mislocalisation, as observed previously by manual counting of primary mouse neurons [Dobson‐Stone et al 2020, Brain 143:783‐799]. Conclusion: The current study validates our methodology as a novel in vitro technique for the quantification of TDP‐43 or FUS mislocalisation that can be used to rapidly and systematically assess the pathogenicity of predicted FTD/ALS gene variants. This methodology can be employed to aid genetic diagnosis of patients carrying novel variants in known FTD/ALS genes, and in the prioritisation of novel candidate genes for further functional analysis. [ABSTRACT FROM AUTHOR]

Background: Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders that share similar clinical and pathological hallmarks, as well as overlapping genetic aetiologies. Previously, we identified that mutations in CYLD can cause FTD‐ALS. CYLD is a lysine‐63 deubiquitinase, and the FTD‐ALS causal mutation CYLDM719V shows significantly increased deubiquitinase activity [Dobson‐Stone et al. 2020, Brain 143:783‐799]. CYLD is known to interact with the protein products of at least three established FTD and ALS genes. We sought to determine whether other FTD‐ALS proteins were influenced by modulation of CYLD. Method: We performed mass spectrometry quantitative proteomic analysis of HEK293 lysates overexpressing wild‐type and mutant CYLD (CYLDWT & CYLDM719V), followed by western blots of total cell lysates from SH‐SY5Y and HEK293 cells overexpressing CYLDWT, CYLDM719V and the deubiquitinase‐inactive mutation CYLDD681G. Densitometry analysis was performed in Image Lab (Bio‐Rad, USA) and normalised to total protein. Result: Mass spectrometry analysis indicated significant differences in expression of TIA1, MATR3, VCP and SFPQ when CYLD was overexpressed. Validation by western blot showed that overexpression of CYLD increased relative protein expression of SFPQ (2.7 fold increase for CYLDWT versus empty vector, p = 0.0048) in SH‐SY5Y cells. This is likely due to deubiquitinase activity, as CYLDD681G did not show such an increase. SFPQ is a nucleic acid binding protein that has been shown to mislocalise from the nucleus to the cytoplasm in FTD and ALS. We are currently examining whether CYLD affects subcellular localisation of SFPQ by western blot and immunofluorescent microscopy analyses. Conclusion: Our study indicates that CYLD overexpression increases SFPQ protein expression via its deubiquitinase activity. However, it remains to be shown whether this mechanism is essential to the pathogenesis of FTD and ALS driven by CYLD. [ABSTRACT FROM AUTHOR]