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1.  Novel CSF biomarkers for frontotemporal lobar degenerations(e–Pub ahead of print) 
Neurology  2010;75(23):2079-2086.
Objective:
To identify antemortem CSF diagnostic biomarkers that can potentially distinguish between the 2 main causes of frontotemporal lobar degeneration (FTLD), i.e., FTLD with TDP-43 pathology (FTLD-TDP) and FTLD with tau pathology (FTLD-tau).
Methods:
CSF samples were collected antemortem from 23 patients with FTLD with known pathology to form a autopsy cohort as part of a comparative biomarker study that additionally included 33 living cognitively normal subjects and 66 patients with autopsy-confirmed Alzheimer disease (AD). CSF samples were also collected from 80 living patients clinically diagnosed with frontotemporal dementia (FTD). Levels of 151 novel analytes were measured via a targeted multiplex panel enriched in neuropeptides, cytokines, and growth factors, along with levels of CSF biomarkers for AD.
Results:
CSF levels of multiple analytes differed between FTLD-TDP and FTLD-tau, including Fas, neuropeptides (agouti-related peptide and adrenocorticotropic hormone), and chemokines (IL-23, IL-17). Classification by random forest analysis achieved high sensitivity for FTLD-TDP (86%) with modest specificity (78%) in the autopsy cohort. When the classification algorithm was applied to a living FTD cohort, semantic dementia was the phenotype with the highest predicted proportion of FTLD-TDP. When living patients with behavioral variant FTD were examined in detail, those predicted to have FTLD-TDP demonstrated neuropsychological differences vs those predicted to have FTLD-tau in a pattern consistent with previously reported trends in autopsy-confirmed cases.
Conclusions:
Clinical cases with FTLD-TDP and FTLD-tau pathology can be potentially identified antemortem by assaying levels of specific analytes that are well-known and readily measurable in CSF.
GLOSSARY
= Alzheimer disease;
= Aguti-related protein;
= angiopoietin-2;
= adrenocorticotropic hormone;
= amyotrophic lateral sclerosis;
= apolipoprotein B;
= behavioral variant FTD;
= corticobasal syndrome;
= frontotemporal dementia;
= frontotemporal lobar degeneration;
= frontotemporal lobar degeneration with tau pathology;
= frontotemporal lobar degeneration with TDP-43 pathology;
= interleukin;
= macrophage-derived chemokine;
= progressive nonfluent aphasia;
= primary progressive aphasia;
= progressive supranuclear palsy;
= S100 calcium binding protein b;
= semantic dementia;
= tumor necrosis factor-related apoptosis-inducing ligand receptor 3.
doi:10.1212/WNL.0b013e318200d78d
PMCID: PMC2995537  PMID: 21048198
2.  TDP-43 protein in plasma may index TDP-43 brain pathology in Alzheimer’s disease and frontotemporal lobar degeneration 
Acta Neuropathologica  2008;116(2):141-146.
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. The proportions of patients with FTD and AD showing raised plasma TDP-43 levels correspond closely to those proportions known from autopsy studies to contain TDP-43 pathological changes in their brains. Raised TDP-43 plasma levels may thereby index TDP-43 pathology within the brain. Plasma TDP-43 levels may be a biomarker that can provide a laboratory test capable of identifying the presence of TDP-43 brain pathology in neurodegenerative disease during life. It may help to distinguish those cases of FTLD with ubiquitin/TDP-43 pathology in their brains from those with tauopathy. As a predictive test, plasma TDP-43 level may have great practical value in directing therapeutic strategies aimed at preventing or removing tau or TDP-43 pathological changes from the brain in FTLD and AD.
doi:10.1007/s00401-008-0389-8
PMCID: PMC2464623  PMID: 18506455
Frontotemporal lobar degeneration; Alzheimer’s disease; TDP-43; Plasma; Biomarker
3.  Clinicopathologic differences among patients with behavioral variant frontotemporal dementia 
Neurology  2007;69(11):1113-1121.
Objective
To characterize the presenting symptoms and signs of patients clinically diagnosed with behavioral variant frontotemporal dementia (bvFTD) and who had different neuropathologic findings on autopsy.
Methods
This study reviewed all patients entered as clinical bvFTD in the National Alzheimer’s Coordinating Center’s database and who had both clinical and neuropathologic data from 2005 to 2011. Among the 107 patients identified, 95 had unambiguous pathologic findings, including 74 with frontotemporal lobar degeneration (bvFTD-FTLD) and 21 with Alzheimer disease (bvFTD-AD). The patients with bvFTD-FTLD were further subdivided into τ-positive (n = 23) or τ-negative (n = 51) histopathology subgroups. Presenting clinical signs and symptoms were compared between these neuropathologic groups.
Results
The patients with bvFTD-FTLD were significantly more likely than patients with bvFTD-AD to have initially predominant personality changes and poor judgment/decision-making. In contrast, patients with bvFTD-AD were more likely than patients with bvFTD-FTLD to have memory difficulty and delusions/hallucinations and agitation. Within the bvFTD-FTLD group, the τ-positive subgroup had more patients with initial behavioral problems and personality change than the τ-negative subgroup, who, in turn, had more patients with initial cognitive impairment and speech problems.
Conclusion
During life, patients with AD pathology may be misdiagnosed with bvFTD if they have an early age at onset and prominent neuropsychiatric features despite having greater memory difficulties and more intact personality and executive functions than patients with bvFTD-FTLD. Among those with FTLD pathology, patients with τ-positive bvFTD were likely to present with behavior/personality changes. These findings offer clues for antemortem recognition of neuropathologic subtypes of bvFTD.
doi:10.1212/01.wnl.0000267701.58488.69
PMCID: PMC3545400  PMID: 17522386
4.  Neuropathological background of phenotypical variability in frontotemporal dementia 
Acta Neuropathologica  2011;122(2):137-153.
Frontotemporal lobar degeneration (FTLD) is the umbrella term encompassing a heterogeneous group of pathological disorders. With recent discoveries, the FTLDs have been show to classify nicely into three main groups based on the major protein deposited in the brain: FTLD-tau, FTLD-TDP and FTLD-FUS. These pathological groups, and their specific pathologies, underlie a number of well-defined clinical syndromes, including three frontotemporal dementia (FTD) variants [behavioral variant frontotemporal dementia (bvFTD), progressive non-fluent aphasia, and semantic dementia (SD)], progressive supranuclear palsy syndrome (PSPS) and corticobasal syndrome (CBS). Understanding the neuropathological background of the phenotypic variability in FTD, PSPS and CBS requires large clinicopathological studies. We review current knowledge on the relationship between the FTLD pathologies and clinical syndromes, and pool data from a number of large clinicopathological studies that collectively provide data on 544 cases. Strong relationships were identified as follows: FTD with motor neuron disease and FTLD-TDP; SD and FTLD-TDP; PSPS and FTLD-tau; and CBS and FTLD-tau. However, the relationship between some of these clinical diagnoses and specific pathologies is not so clear cut. In addition, the clinical diagnosis of bvFTD does not have a strong relationship to any FTLD subtype or specific pathology and therefore remains a diagnostic challenge. Some evidence suggests improved clinicopathological association of bvFTD by further refining clinical characteristics. Unlike FTLD-tau and FTLD-TDP, FTLD-FUS has been less well characterized, with only 69 cases reported. However, there appears to be some associations between clinical phenotypes and FTLD-FUS pathologies. Clinical diagnosis is therefore promising in predicting molecular pathology.
doi:10.1007/s00401-011-0839-6
PMCID: PMC3232515  PMID: 21614463
Frontotemporal lobar degeneration; Progressive supranuclear palsy; Tau; TDP-43; FUS
5.  Clinicopathologic differences among patients with behavioral variant frontotemporal dementia 
Neurology  2013;80(6):561-568.
Objective:
To characterize the presenting symptoms and signs of patients clinically diagnosed with behavioral variant frontotemporal dementia (bvFTD) and who had different neuropathologic findings on autopsy.
Methods:
This study reviewed all patients entered as clinical bvFTD in the National Alzheimer's Coordinating Center's database and who had both clinical and neuropathologic data from 2005 to 2011. Among the 107 patients identified, 95 had unambiguous pathologic findings, including 74 with frontotemporal lobar degeneration (bvFTD-FTLD) and 21 with Alzheimer disease (bvFTD-AD). The patients with bvFTD-FTLD were further subdivided into τ-positive (n = 23) or τ-negative (n = 51) histopathology subgroups. Presenting clinical signs and symptoms were compared between these neuropathologic groups.
Results:
The patients with bvFTD-FTLD were significantly more likely than patients with bvFTD-AD to have initially predominant personality changes and poor judgment/decision-making. In contrast, patients with bvFTD-AD were more likely than patients with bvFTD-FTLD to have memory difficulty and delusions/hallucinations and agitation. Within the bvFTD-FTLD group, the τ-positive subgroup had more patients with initial behavioral problems and personality change than the τ-negative subgroup, who, in turn, had more patients with initial cognitive impairment and speech problems.
Conclusion:
During life, patients with AD pathology may be misdiagnosed with bvFTD if they have an early age at onset and prominent neuropsychiatric features despite having greater memory difficulties and more intact personality and executive functions than patients with bvFTD-FTLD. Among those with FTLD pathology, patients with τ-positive bvFTD were likely to present with behavior/personality changes. These findings offer clues for antemortem recognition of neuropathologic subtypes of bvFTD.
doi:10.1212/WNL.0b013e3182815547
PMCID: PMC3589292  PMID: 23325909
6.  Oculomotor function in frontotemporal lobar degeneration, related disorders and Alzheimer's disease 
Brain  2008;131(5):1268-1281.
Frontotemporal lobar degeneration (FTLD) often overlaps clinically with corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP), both of which have prominent eye movement abnormalities. To investigate the ability of oculomotor performance to differentiate between FTLD, Alzheimer's disease, CBS and PSP, saccades and smooth pursuit were measured in three FTLD subtypes, including 24 individuals with frontotemporal dementia (FTD), 19 with semantic dementia (SD) and six with progressive non-fluent aphasia (PA), as compared to 28 individuals with Alzheimer's disease, 15 with CBS, 10 with PSP and 27 control subjects. Different combinations of oculomotor abnormalities were identified in all clinical syndromes except for SD, which had oculomotor performance that was indistinguishable from age-matched controls. Only PSP patients displayed abnormalities in saccade velocity, whereas abnormalities in saccade gain were observed in PSP > CBS > Alzheimer's disease subjects. All patient groups except those with SD were impaired on the anti-saccade task, however only the FTLD subjects and not Alzheimer's disease, CBS or PSP groups, were able to spontaneously self-correct anti-saccade errors as well as controls. Receiver operating characteristic statistics demonstrated that oculomotor findings were superior to neuropsychological tests in differentiating PSP from other disorders, and comparable to neuropsychological tests in differentiating the other patient groups. These data suggest that oculomotor assessment may aid in the diagnosis of FTLD and related disorders.
doi:10.1093/brain/awn047
PMCID: PMC2367697  PMID: 18362099
oculomotor; frontotemporal lobar degeneration; corticobasal syndrome; progressive supranuclear palsy; Alzheimer's disease
7.  A new subtype of frontotemporal lobar degeneration with FUS pathology 
Brain  2009;132(11):2922-2931.
Frontotemporal dementia (FTD) is a clinical syndrome with a heterogeneous molecular basis. The neuropathology associated with most FTD is characterized by abnormal cellular aggregates of either transactive response DNA-binding protein with Mr 43 kDa (TDP-43) or tau protein. However, we recently described a subgroup of FTD patients, representing around 10%, with an unusual clinical phenotype and pathology characterized by frontotemporal lobar degeneration with neuronal inclusions composed of an unidentified ubiquitinated protein (atypical FTLD-U; aFTLD-U). All cases were sporadic and had early-onset FTD with severe progressive behavioural and personality changes in the absence of aphasia or significant motor features. Mutations in the fused in sarcoma (FUS) gene have recently been identified as a cause of familial amyotrophic lateral sclerosis, with these cases reported to have abnormal cellular accumulations of FUS protein. Because of the recognized clinical, genetic and pathological overlap between FTD and amyotrophic lateral sclerosis, we investigated whether FUS might also be the pathological protein in aFTLD-U. In all our aFTLD-U cases (n = 15), FUS immunohistochemistry labelled all the neuronal inclusions and also demonstrated previously unrecognized glial pathology. Immunoblot analysis of protein extracted from post-mortem aFTLD-U brain tissue demonstrated increased levels of insoluble FUS. No mutations in the FUS gene were identified in any of our patients. These findings suggest that FUS is the pathological protein in a significant subgroup of sporadic FTD and reinforce the concept that FTD and amyotrophic lateral sclerosis are closely related conditions.
doi:10.1093/brain/awp214
PMCID: PMC2768659  PMID: 19674978
frontotemporal lobar degeneration; frontotemporal dementia; FUS; fused in sarcoma; TLS; translocated in liposarcoma
8.  FUS pathology defines the majority of tau- and TDP-43-negative frontotemporal lobar degeneration 
Acta neuropathologica  2010;120(1):33-41.
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. The aFTLD-U subtype of FTLD-FUS is characterised clinically by behavioural variant frontotemporal dementia (bvFTD) and has a particularly young age of onset with a mean of 41 years. Further, this subtype had a high prevalence of psychotic symptoms (36% of cases) and low prevalence of motor symptoms (3% of cases). We did not find FUS mutations in any aFTLD-U case. To date, the only subtype of cases reported to have ubiquitin-positive but tau-, TDP-43- and FUS-negative pathology, termed FTLD-UPS, is the result of charged multivesicular body protein 2B gene (CHMP2B) mutation. We identified three FTLD-UPS cases, which are negative for CHMP2B mutation, suggesting that the full complement of FTLD pathologies is yet to be elucidated.
doi:10.1007/s00401-010-0698-6
PMCID: PMC2887939  PMID: 20490813
FTLD; FUS; FTLD-UPS; Frontotemporal; FTD
9.  FUS pathology defines the majority of tau- and TDP-43-negative frontotemporal lobar degeneration 
Acta Neuropathologica  2010;120(1):33-41.
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. The aFTLD-U subtype of FTLD-FUS is characterised clinically by behavioural variant frontotemporal dementia (bvFTD) and has a particularly young age of onset with a mean of 41 years. Further, this subtype had a high prevalence of psychotic symptoms (36% of cases) and low prevalence of motor symptoms (3% of cases). We did not find FUS mutations in any aFTLD-U case. To date, the only subtype of cases reported to have ubiquitin-positive but tau-, TDP-43- and FUS-negative pathology, termed FTLD-UPS, is the result of charged multivesicular body protein 2B gene (CHMP2B) mutation. We identified three FTLD-UPS cases, which are negative for CHMP2B mutation, suggesting that the full complement of FTLD pathologies is yet to be elucidated.
doi:10.1007/s00401-010-0698-6
PMCID: PMC2887939  PMID: 20490813
FTLD; FUS; FTLD-UPS; Frontotemporal; FTD
10.  Imaging signatures of molecular pathology in behavioral variant frontotemporal dementia 
Journal of Molecular Neuroscience  2011;45(3):372-378.
Pathology underlying behavioral variant frontotemporal dementia (bvFTD) is heterogeneous, with the most common pathologies being Pick’s disease (PiD), corticobasal degeneration (CBD), and FTLD-TDP type 1. Clinical features are unhelpful in differentiating these pathologies. We aimed to determine whether imaging atrophy patterns differ across these pathologies in bvFTD subjects. We identified 15 bvFTD subjects that had volumetric MRI during life and autopsy: five with PiD, five CBD and five FTLD-TDP type 1. Voxel-based morphometry was used to assess atrophy patterns in each bvFTD group compared to 20 age and gender-matched controls. All three pathological groups showed grey matter loss in frontal lobes, although specific patterns of atrophy differed across groups: PiD showed widespread loss in frontal lobes with additional involvement of anterior temporal lobes; CBD showed subtle patterns of loss involving posterior lateral and medial superior frontal lobe; FTLD-TDP type 1 showed widespread loss in frontal, temporal and parietal lobes. Greater parietal loss was observed in FTLD-TDP type 1 compared to both other groups, and greater anterior temporal and medial frontal loss was observed in PiD compared to CBD. Imaging patterns of atrophy in bvFTD vary according to pathological diagnosis and may therefore be helpful in predicting these pathologies in bvFTD.
doi:10.1007/s12031-011-9533-3
PMCID: PMC3401589  PMID: 21556732
Frontotemporal dementia; behavioral variant; Pick’s disease; corticobasal degeneration; TDP-43; atrophy; voxel-based morphometry; MRI
11.  Making the Diagnosis of Frontotemporal Lobar Degeneration 
Context
Autopsy evaluation of the brain of a patient with frontotemporal dementia (FTD) can be daunting to the general pathologist. At some point in their training, most pathologists learn about Pick disease, and can recognize Pick bodies, the morphologic hallmark of Pick disease. Pick disease is a type of frontotemporal lobar degeneration (FTLD), the general category of pathologic process underlying most cases of FTD. The 2 major categories of pathologic FTLD are tauopathies (FTLD-tau) and ubiquitinopathies (FTLD-U). Pick disease is one of the FTLD-tau subtypes and is termed FTLD-tau (PiD).
Objective
To “demystify” FTLDs, and to demonstrate that subtypes of FTLD-tau and FTLD-U can be easily determined by following a logical, stepwise, histochemical, and immunohistochemical investigation of the FTD autopsy brain.
Data Sources
Previously published peer-reviewed articles.
Conclusions
The hope is that this article will be a useful reference for the general pathologist faced with performing a brain autopsy on a decedent with frontotemporal dementia.
doi:10.5858/arpa.2012-0075-RA
PMCID: PMC3629720  PMID: 23451743
12.  MRI Correlates of Protein Deposition and Disease Severity in Postmortem Frontotemporal Lobar Degeneration 
Neuro-degenerative diseases  2009;6(3):106-117.
Background
Frontotemporal lobar degeneration (FTLD) can be classified based on the presence of the microtubule-associated protein tau and the TAR DNA binding protein-43 (TDP-43). Future treatments will likely target these proteins, therefore it is important to identify biomarkers to help predict protein biochemistry.
Objective
To determine whether there is an MRI signature pattern of tau or TDP-43 using a large cohort of FTLD subjects and to investigate how patterns of atrophy change according to disease severity using a large autopsy-confirmed cohort of FTLD subjects.
Methods
Patterns of gray matter loss were assessed using voxel-based morphometry in 37 tau-positive and 44 TDP-43-positive subjects compared to 35 age and gender-matched controls, and compared to each other. Comparisons were also repeated in behavioral variant frontotemporal dementia (bvFTD) subjects (n = 15 tau-positive and n = 30 TDP-43-positive). Patterns of atrophy were also assessed according to performance on the Clinical Dementia Rating (CDR) scale and Mini-Mental State Examination (MMSE).
Results
The tau-positive and TDP-43-positive groups showed patterns of frontotemporal gray matter loss compared to controls with no differences observed between the groups, for all subjects and for bvFTD subjects. Patterns of gray matter loss increased in a graded manner by CDR and MMSE with loss in the frontal lobes, insula and hippocampus in mild subjects, spreading to the temporal and parietal cortices and striatum in more advanced disease.
Conclusion
There is no signature pattern of atrophy for tau or TDP-43; however, patterns of atrophy in FTLD progress with measures of clinical disease severity.
doi:10.1159/000209507
PMCID: PMC2745704  PMID: 19299900
Frontotemporal lobar degeneration; Autopsy; Tau; TAR DNA binding protein-43; Voxel-based morphometry; Clinical Dementia Rating Scale; Mini-Mental State Examination
13.  MRI correlates of protein deposition and disease severity in postmortem frontotemporal lobar degeneration 
Neuro-degenerative diseases  2009;6(3):106-117.
Background
Frontotemporal lobar degeneration (FTLD) can be classified based on the presence of the microtubule associated protein tau and the TAR DNA binding protein-43 (TDP-43). Future treatments will likely target these proteins; therefore it is important to identify biomarkers to help predict protein biochemistry.
Objective
To determine whether there is an MRI signature pattern of tau or TDP-43 using a large cohort of FTLD subjects and to investigate how patterns of atrophy change according to disease severity using a large autopsy-confirmed cohort of FTLD subjects.
Methods
Patterns of grey matter loss were assessed using voxel-based morphometry in 37 tau-positive and 44 TDP-43 positive subjects compared to 35 age and gender-matched controls, and compared to each other. Comparisons were also repeated in behavioral variant frontotemporal dementia (bvFTD) subjects (n=15 tau-positive and n=30 TDP-43 positive). Patterns of atrophy were also assessed according to performance on the clinical dementia rating (CDR) scale and mini-mental state examination (MMSE).
Results
The tau-positive and TDP-43 positive groups showed patterns of frontotemporal grey matter loss compared to controls with no differences observed between the groups, for all subjects and for bvFTD subjects. Patterns of grey matter loss increased in a graded manner by CDR and MMSE with loss in the frontal lobes, insula and hippocampus in mild subjects, spreading to the temporal and parietal cortices and striatum in more advanced disease.
Conclusion
There is no signature pattern of atrophy for tau or TDP-43; however patterns of atrophy in FTLD progress with measures of clinical disease severity.
doi:10.1159/000209507
PMCID: PMC2745704  PMID: 19299900
frontotemporal lobar degeneration; autopsy; tau; TAR DNA binding protein-43; voxel-based morphometry; Clinical Dementia Rating Scale; Mini-Mental State Examination
14.  Atrophy patterns in histologic vs clinical groupings of frontotemporal lobar degeneration 
Neurology  2009;72(19):1653-1660.
Objective:
Predictable patterns of atrophy are associated with the clinical subtypes of frontotemporal dementia (FTD): behavioral variant (bvFTD), semantic dementia (SEMD), and progressive nonfluent aphasia (PNFA). Some studies of pathologic subtypes have also suggested specific atrophy patterns; however, results are inconsistent. Our aim was to test the hypothesis that clinical, but not pathologic, classification (FTD with ubiquitin inclusions [FTD-U] and FTD with tau inclusions [FTD-T]) is associated with predictable patterns of regional atrophy.
Methods:
Magnetic resonance scans of nine FTD-U and six FTD-T patients (histologically confirmed) were compared with 25 controls using voxel-based morphometry (VBM). Analyses were conducted with the patient group classified according to histologic or clinical variant. Additionally, three Alzheimer pathology patients who had the syndrome of SEMD in life (FTD-A) were analyzed.
Results:
The VBM studies in clinical variants confirmed established patterns of atrophy (SEMD, rostral temporal; bvFTD, mesial frontal; PNFA, left insula). FTD-U and FTD-T VBM results were very similar, showing severe atrophy in the temporal poles, mesial frontal lobe, and insulae. A conjunction analysis confirmed this similarity. Subgroup analysis found that SEMD associated with either FTD-T or FTD-U was associated with similar rostral temporal atrophy; however, FTD-A had a qualitatively different pattern of left hippocampal atrophy.
Conclusions:
While there is predictable atrophy for clinical variants of frontotemporal dementia (FTD), histologic FTD variants show no noticeable differences. Reports of specific atrophy profiles are likely the result of idiosyncrasies in small groups. Semantic dementia associated with Alzheimer pathology, however, presented a distinct atrophy pattern.
GLOSSARY
= Alzheimer disease;
= behavioral variant frontotemporal dementia;
= frontotemporal dementia;
= Alzheimer pathology with semantic dementia;
= frontotemporal dementia with tau inclusions;
= frontotemporal dementia with ubiquitin inclusions;
= frontotemporal lobar degeneration;
= Mini-Mental State Examination;
= progressive nonfluent aphasia;
= semantic dementia;
= voxel-based morphometry.
doi:10.1212/WNL.0b013e3181a55fa2
PMCID: PMC2827263  PMID: 19433738
15.  TARDBP 3′-UTR variant in autopsy-confirmed frontotemporal lobar degeneration with TDP-43 proteinopathy 
Acta Neuropathologica  2009;118(5):633-645.
Pathogenic mutations in the gene encoding TDP-43, TARDBP, have been reported in familial amyotrophic lateral sclerosis (FALS) and, more recently, in families with a heterogeneous clinical phenotype including both ALS and frontotemporal lobar degeneration (FTLD). In our previous study, sequencing analyses identified one variant in the 3′-untranslated region (3′-UTR) of the TARDBP gene in two affected members of one family with bvFTD and ALS and in one unrelated clinically assessed case of FALS. Since that study, brain tissue has become available and provides autopsy confirmation of FTLD-TDP in the proband and ALS in the brother of the bvFTD-ALS family and the neuropathology of those two cases is reported here. The 3′-UTR variant was not found in 982 control subjects (1,964 alleles). To determine the functional significance of this variant, we undertook quantitative gene expression analysis. Allele-specific amplification showed a significant increase of 22% (P < 0.05) in disease-specific allele expression with a twofold increase in total TARDBP mRNA. The segregation of this variant in a family with clinical bvFTD and ALS adds to the spectrum of clinical phenotypes previously associated with TARDBP variants. In summary, TARDBP variants may result in clinically and neuropathologically heterogeneous phenotypes linked by a common molecular pathology called TDP-43 proteinopathy.
doi:10.1007/s00401-009-0571-7
PMCID: PMC2783457  PMID: 19618195
Frontotemporal lobar degeneration; Frontotemporal dementia; Motor neuron disease; Amyotrophic lateral sclerosis; TDP-43; TARDBP; 3′-Untranslated region
16.  Neuropathologic diagnostic and nosologic criteria for frontotemporal lobar degeneration: consensus of the Consortium for Frontotemporal Lobar Degeneration 
Acta Neuropathologica  2007;114(1):5-22.
The aim of this study was to improve the neuropathologic recognition and provide criteria for the pathological diagnosis in the neurodegenerative diseases grouped as frontotemporal lobar degeneration (FTLD); revised criteria are proposed. Recent advances in molecular genetics, biochemistry, and neuropathology of FTLD prompted the Midwest Consortium for Frontotemporal Lobar Degeneration and experts at other centers to review and revise the existing neuropathologic diagnostic criteria for FTLD. The proposed criteria for FTLD are based on existing criteria, which include the tauopathies [FTLD with Pick bodies, corticobasal degeneration, progressive supranuclear palsy, sporadic multiple system tauopathy with dementia, argyrophilic grain disease, neurofibrillary tangle dementia, and FTD with microtubule-associated tau (MAPT) gene mutation, also called FTD with parkinsonism linked to chromosome 17 (FTDP-17)]. The proposed criteria take into account new disease entities and include the novel molecular pathology, TDP-43 proteinopathy, now recognized to be the most frequent histological finding in FTLD. TDP-43 is a major component of the pathologic inclusions of most sporadic and familial cases of FTLD with ubiquitin-positive, tau-negative inclusions (FTLD-U) with or without motor neuron disease (MND). Molecular genetic studies of familial cases of FTLD-U have shown that mutations in the progranulin (PGRN) gene are a major genetic cause of FTLD-U. Mutations in valosin-containing protein (VCP) gene are present in rare familial forms of FTD, and some families with FTD and/or MND have been linked to chromosome 9p, and both are types of FTLD-U. Thus, familial TDP-43 proteinopathy is associated with defects in multiple genes, and molecular genetics is required in these cases to correctly identify the causative gene defect. In addition to genetic heterogeneity amongst the TDP-43 proteinopathies, there is also neuropathologic heterogeneity and there is a close relationship between genotype and FTLD-U sub-type. In addition to these recent significant advances in the neuropathology of FTLD-U, novel FTLD entities have been further characterized, including neuronal intermediate filament inclusion disease. The proposed criteria incorporate up-to-date neuropathology of FTLD in the light of recent immunohistochemical, biochemical, and genetic advances. These criteria will be of value to the practicing neuropathologist and provide a foundation for clinical, clinico-pathologic, mechanistic studies and in vivo models of pathogenesis of FTLD.
doi:10.1007/s00401-007-0237-2
PMCID: PMC2827877  PMID: 17579875
Frontotemporal dementia; Semantic dementia; Progressive non-Xuent aphasia; Frontotemporal lobar degeneration; Motor neuron disease; Tauopathy; Ubiquitin; TDP-43 proteinopathy; Progranulin; Valosin-containing protein; Charged multivesicular body protein 2B; Neuronal intermediate filament inclusion disease; Neuropathologic diagnosis
17.  Frequency of ubiquitin and FUS-positive, TDP-43-negative frontotemporal lobar degeneration 
Journal of Neurology  2009;257(5):747-753.
Frontotemporal lobar degeneration (FTLD) is a clinically, genetically and pathologically heterogeneous disorder. Within FTLD with ubiquitin-positive inclusions (FTLD-U), a new pathological subtype named FTLD-FUS was recently found with fused in sarcoma (FUS) positive, TDP-43-negative inclusions, and striking atrophy of the caudate nucleus. The aim of this study was to determine the frequency of FTLD-FUS in our pathological FTLD series, and to describe the clinical, neuroimaging and neuropathological features of FTLD-FUS, especially caudate atrophy. Demographic and clinical data collected prospectively from 387 patients with frontotemporal dementia (FTD) yielded 74 brain specimens. Immunostaining was carried out using a panel of antibodies, including AT-8, ubiquitin, p62, FUS, and TDP-43. Cortical and caudate atrophy on MRI (n = 136) was rated as normal, mild-moderate or severe. Of the 37 FTLD-U cases, 33 were reclassified as FTLD-TDP and four (0.11, 95%: 0.00–0.21) as FTLD-FUS, with ubiquitin and FUS-positive, p62 and TDP-43-negative neuronal intranuclear inclusions (NII). All four FTLD-FUS cases had a negative family history, behavioural variant FTD (bvFTD), and three had an age at onset ≤40 years. MRI revealed mild-moderate or severe caudate atrophy in all, with a mean duration from onset till MRI of 63 months (range 16–119 months). In our total clinical FTD cohort, we found 11 patients (0.03; 95% CI: 0.01–0.05) with bvFTD, negative family history, and age at onset ≤40 years. Caudate atrophy was present in 10 out of 136 MRIs, and included all four FUS-cases. The newly identified FTLD-FUS has a frequency of 11% in FTLD-U, and an estimated frequency of three percent in our clinical FTD cohort. The existence of this pathological subtype can be predicted with reasonable certainty by age at onset ≤40 years, negative family history, bvFTD and caudate atrophy on MRI.
doi:10.1007/s00415-009-5404-z
PMCID: PMC2864899  PMID: 19946779
Frontotemporal lobar degeneration (FTLD); Ubiquitin; p62; TDP-43; FUS
18.  Molecular Characterization of Novel Progranulin (GRN) Mutations in Frontotemporal Dementia 
Human mutation  2008;29(4):512-521.
Frontotemporal dementia (FTD) is a clinical term encompassing dementia characterized by the presence of two major phenotypes: 1) behavioral and personality disorder, and 2) language disorder, which includes primary progressive aphasia and semantic dementia. Recently, the gene for familial frontotemporal lobar degeneration (FTLD) with ubiquitin-positive, tau-negative inclusions (FTLD-U) linked to chromosome 17 was cloned. In the present study, 62 unrelated patients from the Washington University Alzheimer's Disease Research Center and the Midwest Consortium for FTD with clinically diagnosed FTD and/or neuropathologically characterized cases of FTLD-U with or without motor neuron disease (MND) were screened for mutations in the progranulin gene (GRN; also PGRN). We discovered two pathogenic mutations in four families: 1) a single-base substitution within the 3′ splice acceptor site of intron 6/exon 7 (g.5913A>G [IVS6–2A>G]) causing skipping of exon 7 and premature termination of the coding sequence (PTC); and 2) a missense mutation in exon 1 (g.4068C>A) introducing a charged amino acid in the hydrophobic core of the signal peptide at residue 9 (p.A9D). Functional analysis in mutation carriers for the splice acceptor site mutation revealed a 50% decrease in GRN mRNA and protein levels, supporting haploinsufficiency. In contrast, there was no significant difference in the total GRN mRNA between cases and controls carrying the p.A9D mutation. Further, subcellular fractionation and confocal microscopy indicate that although the mutant protein is expressed, it is not secreted, and appears to be trapped within an intracellular compartment, possibly resulting in a functional haploinsufficiency.
doi:10.1002/humu.20681
PMCID: PMC2756561  PMID: 18183624
Frontotemporal dementia; FTD; granulin; progranulin; GRN; PGRN
19.  White Matter Imaging Helps Dissociate Tau from TDP-43 in Frontotemporal Lobar Degeneration 
Background
Frontotemporal lobar degeneration (FTLD) is most commonly associated with TAR-DNA binding protein (TDP-43) or tau pathology at autopsy, but there are no in vivo biomarkers reliably discriminating between sporadic cases. As disease-modifying treatments emerge, it is critical to accurately identify underlying pathology in living patients so that they can be entered into appropriate etiology-directed clinical trials. Patients with tau inclusions (FTLD-TAU) appear to have relatively greater white matter (WM) disease at autopsy than those patients with TDP-43 (FTLD-TDP). In this paper, we investigate the ability of white matter (WM) imaging to help discriminate between FTLD-TAU and FTLD-TDP during life using diffusion tensor imaging (DTI).
Methods
Patients with autopsy-confirmed disease or a genetic mutation consistent with FTLD-TDP or FTLD-TAU underwent multimodal T1 volumetric MRI and diffusion weighted imaging scans. We quantified cortical thickness in GM and fractional anisotropy (FA) in WM. We performed Eigenanatomy, a statistically robust dimensionality reduction algorithm, and used leave-one-out cross-validation to predict underlying pathology. Neuropathological assessment of GM and WM disease burden was performed in the autopsy-cases to confirm our findings of an ante-mortem GM and WM dissociation in the neuroimaging cohort.
Results
ROC curve analyses evaluated classification accuracy in individual patients and revealed 96% sensitivity and 100% specificity for WM analyses. FTLD-TAU had significantly more WM degeneration and inclusion severity at autopsy relative to FTLD-TDP.
Conclusions
These neuroimaging and neuropathological investigations provide converging evidence for greater WM burden associated with FTLD-TAU, and emphasize the role of WM neuroimaging for in vivo discrimination between FTLD-TAU and FTLD-TDP.
doi:10.1136/jnnp-2012-304418
PMCID: PMC3737288  PMID: 23475817
20.  Visual search patterns in semantic dementia show paradoxical facilitation of binding processes 
Neuropsychologia  2011;49(3):468-478.
While patients with Alzheimer’s disease (AD) show deficits in attention, manifested by inefficient performance on visual search, new visual talents can emerge in patients with frontotemporal lobar degeneration (FTLD), suggesting that, at least in some of the patients, visual attention is spared, if not enhanced. To investigate the underlying mechanisms for visual talent in FTLD (behavioral variant FTD [bvFTD] and semantic dementia [SD]) patients, we measured performance on a visual search paradigm that includes both feature and conjunction search, while simultaneously monitoring saccadic eye movements. AD patients were impaired relative to healthy controls (NC) and FTLD patients on both feature and conjunction search. BvFTD patients showed less accurate performance only on the conjunction search task, but slower response times than NC on all three tasks. In contrast, SD patients were as accurate as controls and had faster response times when faced with the largest number of distracters in the conjunction search task. Measurement of saccades during visual search showed that AD patients explored more of the image, whereas SD patients explored less of the image before making a decision as to whether the target was present. Performance on the conjunction search task positively correlated with gray matter volume in the superior parietal lobe, precuneus, middle frontal gyrus and superior temporal gyrus. These data suggest that despite the presence of extensive temporal lobe degeneration, visual talent in SD may be facilitated by more efficient visual search under distracting conditions due to enhanced function in the dorsal frontoparietal attention network.
doi:10.1016/j.neuropsychologia.2010.12.039
PMCID: PMC3046767  PMID: 21215762
Alzheimer’s disease; frontotemporal dementia; conjunction search; voxel-based morphometry; eye movements
21.  Does TDP-43 type confer a distinct pattern of atrophy in frontotemporal lobar degeneration? 
Neurology  2010;75(24):2212-2220.
Objective:
To determine whether TDP-43 type is associated with distinct patterns of brain atrophy on MRI in subjects with pathologically confirmed frontotemporal lobar degeneration (FTLD).
Methods:
In this case-control study, we identified all subjects with a pathologic diagnosis of FTLD with TDP-43 immunoreactive inclusions (FTLD-TDP) and at least one volumetric head MRI scan (n = 42). In each case we applied published criteria for subclassification of FTLD-TDP into FTLD-TDP types 1-3. Voxel-based morphometry was used to compare subjects with each of the different FTLD-TDP types to age- and gender-matched normal controls (n = 30). We also assessed different pathologic and genetic variants within, and across, the different types.
Results:
Twenty-two subjects were classified as FTLD-TDP type 1, 9 as type 2, and 11 as type 3. We identified different patterns of atrophy across the types with type 1 showing frontotemporal and parietal atrophy, type 2 predominantly anterior temporal lobe atrophy, and type 3 predominantly posterior frontal atrophy. Within the FTLD-TDP type 1 group, those with a progranulin mutation had significantly more lateral temporal lobe atrophy than those without. All type 2 subjects were diagnosed with semantic dementia. Subjects with a pathologic diagnosis of FTLD with motor neuron degeneration had a similar pattern of atrophy, regardless of whether they were type 1 or type 3.
Conclusions:
Although there are different patterns of atrophy across the different FTLD-TDP types, it appears that genetic and pathologic factors may also affect the patterns of atrophy.
GLOSSARY
= Alzheimer disease;
= Alzheimer's Disease Research Center;
= behavioral variant frontotemporal dementia;
= corticobasal syndrome;
= Clinical Dementia Rating scale sum of boxes;
= frontotemporal lobar degeneration;
= frontotemporal lobar degeneration with motor neuron degeneration;
= frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions;
= Mini-Mental State Examination;
= neuronal cytoplasmic inclusion;
= progressive nonfluent aphasia;
= semantic dementia;
= Short Test of Mental Status;
= voxel-based morphometry.
doi:10.1212/WNL.0b013e31820203c2
PMCID: PMC3013590  PMID: 21172844
22.  C9ORF72 repeat expansion in clinical and neuropathologic frontotemporal dementia cohorts 
Neurology  2012;79(10):995-1001.
Objective:
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.
Results:
The C9ORF72 repeat expansion was detected in 10% of patients in the clinically diagnosed cohort, rising to 29% in those with a positive family history of early-onset dementia or ALS. The prevalence of psychotic features was significantly higher in expansion-positive cases (56% vs 14%). In the pathology cohort, 41% of TDP-43-positive cases harbored the repeat expansion, and all exhibited type B pathology. One of the 17 expansion-positive probands was homozygous for the “nonrisk” G allele of rs3849942.
Conclusions:
The C9ORF72 repeat expansion is a relatively common cause of FTD in Australian populations, and is especially common in those with FTD-ALS, psychotic features, and a strong family history. Detection of a repeat expansion on the 9p21 putative “nonrisk” haplotype suggests that not all mutation carriers are necessarily descended from a common founder and indicates that the expansion may have occurred on multiple haplotype backgrounds.
doi:10.1212/WNL.0b013e3182684634
PMCID: PMC3430710  PMID: 22875086
23.  The Spectrum of Mutations in Progranulin 
Archives of neurology  2010;67(2):161-170.
Background
Mutation in the progranulin gene (GRN) can cause frontotemporal dementia (FTD). However, it is unclear whether some rare FTD-related GRN variants are pathogenic and whether neurodegenerative disorders other than FTD can also be caused by GRN mutations.
Objectives
To delineate the range of clinical presentations associated with GRN mutations and to define pathogenic candidacy of rare GRN variants.
Design
Case-control study.
Setting
Clinical and neuropathology dementia research studies at 8 academic centers.
Participants
Four hundred thirty-four patients with FTD, including primary progressive aphasia, semantic dementia, FTD/amyotrophic lateral sclerosis (ALS), FTD/motor neuron disease, corticobasal syndrome/corticobasal degeneration, progressive supranuclear palsy, Pick disease, dementia lacking distinctive histopathology, and pathologically confirmed cases of frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U); and 111 non-FTD cases (controls) in which TDP-43 deposits were a prominent neuropathological feature, including subjects with ALS, Guam ALS and/or parkinsonism dementia complex, Guam dementia, Alzheimer disease, multiple system atrophy, and argyrophilic grain disease.
Main Outcome Measures
Variants detected on sequencing of all 13 GRN exons and at least 80 base pairs of flanking introns, and their pathogenic candidacy determined by in silico and ex vivo splicing assays.
Results
We identified 58 genetic variants that included 26 previously unknown changes. Twenty-four variants appeared to be pathogenic, including 8 novel mutations. The frequency of GRN mutations was 6.9% (30 of 434) of all FTD-spectrum cases, 21.4% (9 of 42) of cases with a pathological diagnosis of FTLD-U, 16.0% (28 of 175) of FTD-spectrum cases with a family history of a similar neurodegenerative disease, and 56.2% (9 of 16) of cases of FTLD-U with a family history.
Conclusions
Pathogenic mutations were found only in FTD-spectrum cases and not in other related neurodegenerative diseases. Haploinsufficiency of GRN is the predominant mechanism leading to FTD.
doi:10.1001/archneurol.2009.328
PMCID: PMC2901991  PMID: 20142524
24.  Frontotemporal Dementia: Implications for Understanding Alzheimer Disease 
Frontotemporal dementia (FTD) comprises a group of behavioral, language, and movement disorders. On the basis of the nature of the characteristic protein inclusions, frontotemporal lobar degeneration (FTLD) can be subdivided into the common FTLD-tau and FTLD-TDP as well as the less common FTLD-FUS and FTLD-UPS. Approximately 10% of cases of FTD are inherited in an autosomal-dominant manner. Mutations in seven genes cause FTD, with those in tau (MAPT), chromosome 9 open reading frame 72 (C9ORF72), and progranulin (GRN) being the most common. Mutations in MAPT give rise to FTLD-tau and mutations in C9ORF72 and GRN to FTLD-TDP. The other four genes are transactive response–DNA binding protein-43 (TARDBP), fused in sarcoma (FUS), valosin-containing protein (VCP), and charged multivesicular body protein 2B (CHMP2B). Mutations in TARDBP and VCP give rise to FTLD-TDP, mutations in FUS to FTLD-FUS, and mutations in CHMP2B to FTLD-UPS. The discovery that mutations in MAPT cause neurodegeneration and dementia has important implications for understanding Alzheimer disease.
Mutations in the tau (MAPT) gene account for ∼5% of frontotemporal dementia cases. They give rise to characteristic protein inclusions, providing insight into tau pathology in Alzheimer disease.
doi:10.1101/cshperspect.a006254
PMCID: PMC3281593  PMID: 22355793
25.  Clinical and neuropathologic heterogeneity of c9FTD/ALS associated with hexanucleotide repeat expansion in C9ORF72 
Acta Neuropathologica  2011;122(6):673-690.
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are part of a disease spectrum associated with TDP-43 pathology. Strong evidence supporting this is the existence of kindreds with family members affected by FTD, ALS or mixed features of FTD and ALS, referred to as FTD-MND. Some of these families have linkage to chromosome 9, with hexanucleotide expansion mutation in a noncoding region of C9ORF72. Discovery of the mutation defines c9FTD/ALS. Prior to discovery of mutations in C9ORF72, it was assumed that TDP-43 pathology in c9FTD/ALS was uniform. In this study, we examined the neuropathology and clinical features of 20 cases of c9FTD/ALS from a brain bank for neurodegenerative disorders. Included are six patients clinically diagnosed with ALS, eight FTD, one FTD-MND and four Alzheimer type dementia. Clinical information was unavailable for one patient. Pathologically, the cases all had TDP-43 pathology, but there were three major pathologic groups: ALS, FTLD-MND and FTLD-TDP. The ALS cases were morphologically similar to typical sporadic ALS with almost no extramotor TDP-43 pathology; all had oligodendroglial cytoplasmic inclusions. The FTLD-MND showed predominantly Mackenzie Type 3 TDP-43 pathology, and all had ALS-like pathology in motor neurons, but more extensive extramotor pathology, with oligodendroglial cytoplasmic inclusions and infrequent hippocampal sclerosis. The FTLD-TDP cases had several features similar to FTLD-TDP due to mutations in the gene for progranulin, including Mackenzie Type 1 TDP-43 pathology with neuronal intranuclear inclusions and hippocampal sclerosis. FTLD-TDP patients were older and some were thought to have Alzheimer type dementia. In addition to the FTD and ALS clinical presentations, the present study shows that c9FTD/ALS can have other presentations, possibly related to age of onset and presence of hippocampal sclerosis. Moreover, there is pathologic heterogeneity not only between ALS and FTLD, but within the FTLD group. Further studies are needed to address the molecular mechanism of clinical and pathological heterogeneity of c9FTD/ALS due to mutations in C9ORF72.
doi:10.1007/s00401-011-0907-y
PMCID: PMC3277860  PMID: 22083254

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