The cellular expression and proteolytic processing of the amyloid precursor protein is independent of TDP-43.

Alzheimer's disease (AD) is a neurodegenerative condition, of which one of the cardinal pathological hallmarks is the extracellular accumulation of amyloid β (Aβ) peptides. These peptides are generated via proteolysis of the amyloid precursor protein (APP), in a manner dependent on the β-secretase, BACE1 and the multicomponent γ-secretase complex. Recent data also suggest a contributory role in AD of transactive response DNA binding protein 43 (TDP-43).

Expression of C9orf72-related dipeptides impairs motor function in a vertebrate model.

Large expansions of hexanucleotide GGGGCC (G4C2) repeats (hundreds to thousands) in the first intron of the chromosome 9 open reading frame 72 (C9orf72) locus are the strongest known genetic factor associated with amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Different hypotheses exist about the underlying disease mechanism including loss of function by haploinsufficiency, toxicity arising as a result of RNA or dipeptide repeats (DPRs). Five different DPRs are produced by repeat-associated non-ATG-initiated translation of the G4C2 repeats.

Modelling C9orf72 dipeptide repeat proteins of a physiologically relevant size.

C9orf72 expansions are the most common genetic cause of FTLD and MND identified to date. Although being intronic, the expansion is translated into five different dipeptide repeat proteins (DPRs) that accumulate within patients' neurons. Attempts have been made to model DPRs in cell and animals.

Identification of biological pathways regulated by PGRN and GRN peptide treatments using transcriptome analysis.

Mutations in progranulin (PGRN) have been linked to two neurodegenerative disorders, heterozygote mutations with frontotemporal lobar degeneration (FTLD) and homozygote mutations with neuronal ceroid lipofuscinosis (NCL). Human PGRN is 593aa secreted growth factor, made up of seven and a half repeats of a highly conserved granulin motif that is cleaved to produce the granulin peptides A-G and paragranulin. While it is thought that PGRN protects against neurodegeneration through its role in inflammation and tissue repair, the role of PGRN and granulins in the nervous system is currently unclear.

Genetic risk factors for the posterior cortical atrophy variant of Alzheimer's disease.

Introduction: The genetics underlying posterior cortical atrophy (PCA), typically a rare variant of Alzheimer's disease (AD), remain uncertain.

Methods: We genotyped 302 PCA patients from 11 centers, calculated risk at 24 loci for AD/DLB and performed an exploratory genome-wide association study.

Results: We confirm that variation in/near APOE/TOMM40 (P = 6 × 10(-14)) alters PCA risk, but with smaller effect than for typical AD (PCA: odds ratio [OR] = 2.

Small deletion in C9orf72 hides a proportion of expansion carriers in FTLD.

Frontotemporal lobar degeneration is a highly familial disease and the most common known genetic cause is the repeat expansion mutation in the gene C9orf72. We have identified 2 brothers with an expansion mutation in C9orf72 using Southern blotting that is undetectable using repeat-primed polymerase chain reaction. Sequencing using high concentrations of DNA denaturants of a bacterial artificial chromosome clone obtained from one of the brothers identified a 10-base pair deletion adjacent to the expansion that presumably confers strong secondary structure that interferes with the genotyping.

Plasma levels of progranulin and interleukin-6 in frontotemporal lobar degeneration.

We have measured plasma progranulin and interleukin-6 in 230 patients with frontotemporal lobar degeneration (FTLD), 104 patients with Alzheimer's disease, and 161 control subjects. We have replicated previous findings of decreased levels of progranulin protein in FTLD because of mutations in GRN and show this is not observed in FTLD cases because of other causes. interleukin-6 levels were increased in FTLD overall, but these did not discriminate between clinical and genetic subtypes.

p62/SQSTM1 analysis in frontotemporal lobar degeneration.

Mutations in the gene p62/SQSTM1 have been reported as a relatively rare cause of frontotemporal lobar degeneration (FTLD). To establish whether this was the case for cases of FTLD from the United Kingdom, we sequenced the sequenced the entire open reading frame of this gene in a large cohort of patients. We identified 3 novel mutations in p62/SQSTM1 in 4 patients.

Pathogenesis/genetics of frontotemporal dementia and how it relates to ALS.

One of the most interesting findings in the field of neurodegeneration in recent years is tfche discovery of a genetic mutation in the C9orf72 gene, the most common mutation found to be causative of sporadic and familial frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS) and concomitant FTD-ALS (DeJesus-Hernandez et al., 2011b; Renton et al., 2011).

Analysis of the hexanucleotide repeat in C9ORF72 in Alzheimer's disease.

Frontotemporal lobar degeneration (FTLD) is a highly familial neurodegenerative disease. It has recently been shown that the most common genetic cause of FTLD and amyotrophic lateral sclerosis (ALS) is a hexanucleotide repeat expansion in C9ORF72. To investigate whether this expansion was specific to the FTLD/ALS disease spectrum, we genotyped the hexanucleotide repeat region of C9ORF72 in a large cohort of patients with Alzheimer's disease (AD).

Distinct clinical and pathological characteristics of frontotemporal dementia associated with C9ORF72 mutations.

The identification of a hexanucleotide repeat expansion in the C9ORF72 gene as the cause of chromosome 9-linked frontotemporal dementia and motor neuron disease offers the opportunity for greater understanding of the relationship between these disorders and other clinical forms of frontotemporal lobar degeneration. In this study, we screened a cohort of 398 patients with frontotemporal dementia, progressive non-fluent aphasia, semantic dementia or mixture of these syndromes for mutations in the C9ORF72 gene. Motor neuron disease was present in 55 patients (14%).

TDP-43 pathological changes in early onset familial and sporadic Alzheimer's disease, late onset Alzheimer's disease and Down's syndrome: association with age, hippocampal sclerosis and clinical phenotype.

TDP-43 immunoreactive (TDP-43-ir) pathological changes were investigated in the temporal cortex and hippocampus of 11 patients with autosomal dominant familial forms of Alzheimer's disease (FAD), 169 patients with sporadic AD [85 with early onset disease (EOAD) (i.e before 65 years of age), and 84 with late onset after this age (LOAD)], 50 individuals with Down's Syndrome (DS) and 5 patients with primary hippocampal sclerosis (HS). TDP-43-ir pathological changes were present, overall, in 34/180 of AD cases.

Genetic and clinical features of progranulin-associated frontotemporal lobar degeneration.

Objective: To assess the relative frequency of unique mutations and their associated characteristics in 97 individuals with mutations in progranulin (GRN), an important cause of frontotemporal lobar degeneration (FTLD).

Participants And Design: A 46-site International Frontotemporal Lobar Degeneration Collaboration was formed to collect cases of FTLD with TAR DNA-binding protein of 43-kDa (TDP-43)-positive inclusions (FTLD-TDP). We identified 97 individuals with FTLD-TDP with pathogenic GRN mutations (GRN+ FTLD-TDP), assessed their genetic and clinical characteristics, and compared them with 453 patients with FTLD-TDP in which GRN mutations were excluded (GRN- FTLD-TDP).

The most common type of FTLD-FUS (aFTLD-U) is associated with a distinct clinical form of frontotemporal dementia but is not related to mutations in the FUS gene.

Frontotemporal lobar degeneration (FTLD) is clinically, pathologically and genetically heterogeneous. Recent descriptions of a pathological sub-type that is ubiquitin positive, TDP-43 negative and immunostains positive for the Fused in Sarcoma protein (FUS) raises the question whether it is associated with a distinct clinical phenotype identifiable on clinical grounds, and whether mutations in the Fused in Sarcoma gene (FUS) might also be associated with FTLD. Examination of a pathological series of 118 cases of FTLD from two centres, showing tau-negative, ubiquitin-positive pathology, revealed FUS pathology in five patients, four classified as atypical FTLD with ubiquitin inclusions (aFTLD-U), and one as neuronal intermediate filament inclusion disease (NIFID).

Analysis of optineurin in frontotemporal lobar degeneration.

Frontotemporal lobar degeneration (FTLD) can occur jointly with amyotrophic lateral sclerosis (ALS), and these 2 conditions share a genetic risk factor on chromosome 9. It has been reported that mutations in optineurin (OPTN) can cause ALS. Therefore, we sequenced OPTN in 371 FTLD cases but no mutations were detected, suggesting changes in OPTN do not cause FTLD.

FUS pathology defines the majority of tau- and TDP-43-negative frontotemporal lobar degeneration.

Through an international consortium, we have collected 37 tau- and TAR DNA-binding protein 43 (TDP-43)-negative frontotemporal lobar degeneration (FTLD) cases, and present here the first comprehensive analysis of these cases in terms of neuropathology, genetics, demographics and clinical data. 92% (34/37) had fused in sarcoma (FUS) protein pathology, indicating that FTLD-FUS is an important FTLD subtype. This FTLD-FUS collection specifically focussed on aFTLD-U cases, one of three recently defined subtypes of FTLD-FUS.

No association of PGRN 3'UTR rs5848 in frontotemporal lobar degeneration.

Frontotemporal lobar degeneration (FTLD) is a highly familial neurodegenerative disease. It has been claimed that homozygosity of the SNP rs5848 located in the 3'UTR of progranulin increases risk for FTLD. We have attempted to replicate the association of rs5848 in three independent FTLD cohorts.

Recent origin and spread of a common Welsh MAPT splice mutation causing frontotemporal lobar degeneration.

IVS10+16C>T is the most prevalent mutation in the microtubule-associated protein tau gene (MAPT) causing frontotemporal lobar degeneration (FTLD) in populations of British descent. A highly conserved 17q21 haplotype was identified in IVS10+16C>T chromosomes from North Wales, Greater Manchester and the London areas of the UK, Australia, and the USA, suggesting the occurrence of a common founder effect. To test this hypothesis, the age of the mutation was estimated by parametric and Bayesian analysis of linkage disequilibrium's decay over generations, and the results were compared with historical and geographical data on FTLD families.

Ubiquitin associated protein 1 is a risk factor for frontotemporal lobar degeneration.

Frontotemporal lobar degeneration (FTLD) is now recognised as a common form of early onset dementia. Up to 40% of patients have a family history of disease demonstrating a large genetic component to its etiology. Linkage to chromosome 9p21 has recently been reported in families with this disorder.

Progressive anomia revisited: focal degeneration associated with progranulin gene mutation.

In 2003 we reported a case study of a patient, Newton who presented with a progressive circumscribed anomia in association with focal left hemisphere atrophy. Remarkably, he could spell aloud the names of objects that he could not name, indicating dissociated access to phonology and orthography. We now present follow-up clinical data, post-mortem histopathological findings, and results of molecular genetic analysis.

TDP-43 protein in plasma may index TDP-43 brain pathology in Alzheimer's disease and frontotemporal lobar degeneration.

Autopsy studies have shown that about 55% of patients with frontotemporal lobar degeneration (FTLD) and 25% of patients with Alzheimer's disease (AD) harbour TDP-43 immunoreactive pathological changes in their brains. Using ELISA, we investigated whether we could detect the presence, or increased amounts, of TDP-43 in plasma of patients with FTLD and AD compared to normal control subjects. We detected elevated levels of TDP-43 protein in plasma of 46% patients with FTLD with clinical frontotemporal dementia (FTD) and 22% patients with AD, compared to 8% of control subjects.

Parietal lobe deficits in frontotemporal lobar degeneration caused by a mutation in the progranulin gene.

Objective: To describe the clinical, neuropsychologic, and radiologic features of a family with a C31LfsX35 mutation in the progranulin gene CCDS11483.1).

Design: Case series.