Identified genetic mutations cause 20% of frontotemporal dementia (FTD) and 5-10% of amyotrophic lateral sclerosis (ALS) cases: however, for the remainder of patients the origin of disease is uncertain. The overlap in genetic, clinical and pathological presentation of FTD and ALS suggests these two diseases are related. Post-mortem, ~ 95% of ALS and ~ 50% of FTD patients show redistribution of the nuclear protein TDP-43 to the cytoplasm within affected neurons, while ~ 5% ALS and ~ 10% FTD show mislocalisation of FUS protein.
View Article and Find Full Text PDFFrontotemporal dementia and amyotrophic lateral sclerosis are clinically and pathologically overlapping disorders with shared genetic causes. We previously identified a disease locus on chromosome 16p12.1-q12.
View Article and Find Full Text PDFAlzheimer's disease is characterized by abnormal amyloid-β (Aβ) peptide accumulation beginning decades before symptom onset. An effective prophylactic treatment aimed at arresting the amyloidogenic pathway would therefore need to be initiated prior to the occurrence of Aβ pathology. The SIGMAR1 gene encodes a molecular chaperone that modulates processing of the amyloid-β protein precursor (AβPP).
View Article and Find Full Text PDFSee Josephs (doi:10.1093/brain/awx367) for a scientific commentary on this article.In many neurodegenerative disorders, familial forms have provided important insights into the pathogenesis of their corresponding sporadic forms.
View Article and Find Full Text PDFStudies investigating the pathogenic role of the microtubule associated protein tau (MAPT) gene in Parkinson's disease (PD) have indicated that DNA methylation of the promoter region is aberrant in disease, leading to dysregulated MAPT expression. We examined two potential regulators of MAPT gene expression in respect to PD, a promoter-associated long non-coding RNA MAPT-AS1, and DNA methyltransferases (DNMTs), enzymes responsible for new and maintenance of DNA methylation. We assessed the relationship between expression levels of MAPT and the candidate MAPT-AS1, DNMT1, DNMT3A and DNMT3B transcripts in four brain regions with varying degrees of cell loss and pathology (putamen, anterior cingulate cortex, visual cortex and cerebellum) in N = 10 PD and N = 10 controls.
View Article and Find Full Text PDFThe MAPT gene is a risk locus for multiple neurodegenerative diseases, including idiopathic Parkinson's and Alzheimer's disease. We examined whether altered DNA methylation of the MAPT promoter, with its potential to modulate gene expression, was a common phenomenon in Alzheimer's disease patients with differing aetiologies. We measured MAPT promoter methylation in a brain tissue cohort of early-onset Alzheimer's disease (EOAD) with defined causative mutations in the PSEN1 gene (Normal = 10, PSEN1 AD = 10), and idiopathic late-onset Alzheimer's disease (Normal = 12, LOAD = 12).
View Article and Find Full Text PDFParkinson'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).
View Article and Find Full Text PDFFrontotemporal dementia (FTD) is associated with motor neurone disease (FTD-MND), corticobasal syndrome (CBS) and progressive supranuclear palsy syndrome (PSPS). Together, this group of disorders constitutes a major cause of young-onset dementia. One of the three clinical variants of FTD is progressive nonfluent aphasia (PNFA), which is focused on in this study.
View Article and Find Full Text PDFA hexanucleotide repeat expansion in C9ORF72 has been established as a common cause of frontotemporal dementia (FTD). However, the minimum repeat number necessary for disease pathogenesis is not known. The aims of our study were to determine the frequency of the C9ORF72 repeat expansion in two FTD patient collections (one Australian and one Spanish, combined n = 190), to examine C9ORF72 expansion allele length in a subset of FTD patients, and to examine C9ORF72 allele length in 'non-expansion' patients (those with <30 repeats).
View Article and Find Full Text PDFObjective: To determine the frequency of a hexanucleotide repeat expansion in C9ORF72, a gene of unknown function implicated in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), in Australian FTD patient cohorts and to examine the clinical and neuropathologic phenotypes associated with this expansion.
Methods: We examined a clinically ascertained FTD cohort (n = 89) and a neuropathologically ascertained cohort of frontotemporal lobar degeneration cases with TDP-43 pathology (FTLD-TDP) (n = 22) for the C9ORF72 hexanucleotide repeat expansion using a repeat primed PCR assay. All expansion-positive patients were genotyped for rs3849942, a surrogate marker for the chromosome 9p21 risk haplotype previously associated with FTD and ALS.
Apolipoprotein E (APOE) ε4 allele and sigma-1 receptor (SIGMAR1) c.5C (Q2P) polymorphisms have been acknowledged as risk factors for developing Alzheimer's disease (AD). However, whether these polymorphisms influence the disease process is unclear.
View Article and Find Full Text PDFObjective: We examined the epistatic effect between haplotypes of glycogen synthase kinase-3beta (GSK3B) gene and microtubule-associated protein Tau (MAPT) gene in Alzheimer's disease (AD).
Methods: A genetic association study of three AD cohorts was made. Linear regression analyses were used to examine effects of MAPT polymorphisms on gene expression and alternative splicing.
Familial Alzheimer's disease due to presenilin 1 (PSEN1) mutations shows considerable phenotypic variability with differences in neuropathology and neurological symptoms. Spastic paraparesis is a common neurological phenotype associated with Alzheimer's disease arising from PSEN1 mutations. To investigate whether known genes that cause spastic paraparesis could act as Alzheimer's disease-modifier genes, we sequenced nine spastic paraparesis genes in three Alzheimer's disease families with PSEN1 exon 9 deletions.
View Article and Find Full Text PDFParkinson's disease (PD) is a neurodegenerative disorder characterized by a combination of motor symptoms. We identified two functional single nucleotide polymorphisms in the glycogen synthase kinase-3beta gene (GSK3B). A promoter single nucleotide polymorphism (rs334558) is associated with transcriptional strength in vitro in which the T allele has greater activity.
View Article and Find Full Text PDFTau gene mutations with insoluble Tau neuropathology have been identified in pedigrees with frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). Other neurodegenerative diseases, including progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), are also characterised by insoluble Tau neuropathology. This study sought to determine the nature and frequency of tau gene mutations in an affected proband cohort of patients within this spectrum of neurodegenerative diseases.
View Article and Find Full Text PDFA primary haplotype (H1) of the microtubule-associated protein Tau (MAPT) gene is associated with Parkinson's disease (PD). However, the mechanism for disease susceptibility remains unknown. We examined the promoter region of MAPT and identified single nucleotide polymorphisms and insertions of 1 to 11 nucleotides.
View Article and Find Full Text PDFThe mutation L271V in exon 8 of the presenilin-1 (PS-1) gene was detected in an Alzheimer's disease pedigree. Neuropathological examination of affected individuals identified variant, large, non-cored plaques without neuritic dystrophy, reminiscent of cotton wool plaques. Biochemical analysis of L271V mutation showed that it increased secretion of the 42-amino acid amyloid-beta peptide, suggesting a pathogenic mutation.
View Article and Find Full Text PDFThe most frequently mutated gene resulting in dominantly inherited Alzheimer's disease is presenilin-1. We have used antibodies against advanced glycation endproducts (AGE) in brain tissue sections of four patients with three different presenilin I mutations. Accumulation of intracellular AGE was observed in 75-95% of pyramidal neurons in patients with presenilin-1 mutations, far exceeding the percentage of presenilin-1-, tau- or ubiquitin-positive neurons.
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