Frontotemporal Dementia

Complex MONDO:0017276 Pathograph 15 Show in embeddings browser Dementia Neurodegenerative Disease

Frontotemporal Dementia (FTD) is a group of neurodegenerative disorders characterized by progressive deterioration of the frontal and temporal lobes of the brain. It presents with prominent changes in personality, behavior, and/or language, typically with onset before age 65. FTD is associated with abnormal accumulation of tau, TDP-43, or (less commonly) FUS proteins.

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6
Pathophys.
4
Phenotypes
15
Pathograph
4
Genes
2
Medical Actions
5
Subtypes
1
Datasets
10
References
2
Deep Research
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Classifications

Harrison's Part
NEUROLOGIC
Mechanistic Nosology
tauopathy proteotoxic disease
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Subtypes

5
Behavioral Variant Frontotemporal Dementia (bvFTD) MONDO:0017160
MAPT hgnc:6893 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in MAPT (hgnc:6893). hgnc:6893 is a gene from the HUGO Gene Nomenclature Committee. C9orf72 hgnc:28337 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in C9orf72 (hgnc:28337). hgnc:28337 is a gene from the HUGO Gene Nomenclature Committee.
The most common clinical presentation of FTD, characterized by progressive behavioral and personality change with frontal-lobe-predominant atrophy. Preferentially associated with MAPT mutations, which show earlier onset, prominent disinhibition, stereotyped behaviors, and temporal-predominant atrophy; also a common presentation in C9orf72 carriers, who additionally show psychotic symptoms and paradoxical social warmth.
Show evidence (1 reference)
PMID:26473392 SUPPORT Human Clinical
"MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy."
Confirms MAPT mutations preferentially produce the behavioral-variant clinical phenotype with early disinhibition and temporal-predominant atrophy.
Semantic Variant Primary Progressive Aphasia (svPPA / Semantic Dementia) MONDO:0010857
A language-predominant FTD syndrome characterized by progressive loss of semantic knowledge (anomia, impaired word comprehension, surface dyslexia) with anterior temporal lobe degeneration. One of the three canonical PPA variants (with nonfluent/agrammatic and logopenic) defined by international consensus criteria. Typically sporadic with underlying TDP-43 type C pathology, showing weaker association with the three major FTD genes than the behavioral or nonfluent variants.
Show evidence (1 reference)
PMID:21325651 SUPPORT Human Clinical
"Criteria for the 3 variants of PPA--nonfluent/agrammatic, semantic, and logopenic--were developed by an international group of PPA investigators who convened on 3 occasions to operationalize earlier published clinical descriptions for PPA subtypes."
Establishes semantic variant PPA as one of the three internationally standardized clinical PPA subtypes within the FTD spectrum.
Nonfluent/Agrammatic Variant Primary Progressive Aphasia (nfvPPA) MONDO:0015059
GRN hgnc:4601 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in GRN (hgnc:4601). hgnc:4601 is a gene from the HUGO Gene Nomenclature Committee.
A language-predominant FTD syndrome characterized by agrammatism, laborious non-fluent speech, and apraxia of speech, with relatively preserved comprehension. Preferentially associated with GRN mutations (older age at death, TDP-43 type A pathology) and also seen with C9orf72 expansions; non-fluent aphasia links to TDP-43 type A pathology in both groups.
Show evidence (2 references)
PMID:26473392 SUPPORT Human Clinical
"GRN patients were older at death and more likely to present with non-fluent aphasia."
Confirms GRN mutations preferentially produce the nonfluent/agrammatic-aphasia clinical phenotype.
PMID:26473392 SUPPORT Human Clinical
"Non-fluent aphasia was linked to TDP subtype A in both GRN and C9orf72 cases and ALS with subtype B."
Links the nonfluent-aphasia phenotype to TDP-43 type A pathology across both GRN- and C9orf72-associated FTD.
Frontotemporal Dementia with Motor Neuron Disease (FTD-MND / FTD-ALS) MONDO:0017161
C9orf72 hgnc:28337 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in C9orf72 (hgnc:28337). hgnc:28337 is a gene from the HUGO Gene Nomenclature Committee.
FTD co-occurring with clinical motor neuron disease/ALS, almost exclusively linked to the C9orf72 hexanucleotide repeat expansion. C9orf72-associated ALS-FTD cases show more psychotic symptoms and paradoxical social warmth than MAPT- or GRN-associated FTD, and ALS co-occurrence links to TDP-43 type B pathology.
Show evidence (2 references)
PMID:26473392 SUPPORT Human Clinical
"C9orf72 patients alone showed a co-occurrence of ALS."
Confirms that ALS co-occurrence in this FTD cohort was exclusive to C9orf72 mutation carriers.
PMID:26473392 SUPPORT Human Clinical
"Non-fluent aphasia was linked to TDP subtype A in both GRN and C9orf72 cases and ALS with subtype B."
Links ALS co-occurrence in C9orf72-associated FTD to TDP-43 type B pathology.
FTD3 (CHMP2B-related frontotemporal dementia-amyotrophic lateral sclerosis) MONDO:0010936
CHMP2B hgnc:24537 HUGO Gene Nomenclature Committee (hgnc) Relation: this subtype is caused by variation in this gene This subtype is caused by variation in CHMP2B (hgnc:24537). hgnc:24537 is a gene from the HUGO Gene Nomenclature Committee.
The chromosome 3-linked form, defined by heterozygous CHMP2B variants and originally delineated in a large Danish pedigree. It is a molecular subtype rather than a clinical one, and it is the reason this entry's molecular classification is not exhausted by tau, TDP-43 and FUS: its inclusions are ubiquitin- and p62-positive but TDP-43-negative, which is the FTLD-UPS class named in the FUS Proteinopathy node's description. Presentation is usually FTD, with ALS features in a subset, and MONDO files the class under both behavioral variant FTD and familial ALS; it is kept here rather than at the ALS entry because the dementia phenotype is the usual one.
Show evidence (2 references)
PMID:20301378 SUPPORT Human Clinical
"CHMP2B-related frontotemporal dementia (FTD)-amyotrophic lateral sclerosis (ALS) is characterized most frequently by FTD with subtle personality changes and slowly progressive behavioral changes, dysexecutive syndrome, and language disturbances."
GeneReviews establishes that the CHMP2B entity presents most frequently as frontotemporal dementia, which is what places this subtype on this entry rather than on the ALS entry.
PMID:16041373 SUPPORT Human Clinical
"We have previously reported a large Danish pedigree with autosomal dominant frontotemporal dementia (FTD) linked to chromosome 3 (FTD3). Here we identify a mutation in CHMP2B, encoding a component of the endosomal ESCRTIII complex, and show that it results in aberrant mRNA splicing in tissue..."
The founding gene-disease report: it ties the chromosome 3-linked FTD3 locus to a CHMP2B splicing mutation, which is this subtype's defining genotype.
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Pathophysiology

6
TDP-43 Proteinopathy
TAR DNA-binding protein of 43 kDa (TDP-43) is the main ubiquitinated protein in tau-negative frontotemporal lobar degeneration (FTLD-TDP), accounting for over 50% of FTD cases. TDP-43 is typically a nuclear protein, and its aggregation and cytoplasmic translocation are thought to represent major pathogenic steps. The abnormal accumulation leads to neuronal dysfunction and death.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
GRN hgnc:4601 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves GRN (hgnc:4601). hgnc:4601 is a gene from the HUGO Gene Nomenclature Committee. C9orf72 hgnc:28337 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves C9orf72 (hgnc:28337). hgnc:28337 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Neuronal Death
Behavioral Changes
Aphasia
Show evidence (2 references)
PMID:26473392 SUPPORT Human Clinical
"MAPT cases had tau and GRN and C9orf72, with one exception, TDP-43 pathology."
Clinico-pathological correlation in a gene-positive cohort assigns GRN and C9orf72 carriers to TDP-43 pathology and MAPT carriers to tau, which is what places these two genes on this node and MAPT on the tau node.
PMID:19664364 SUPPORT
"TDP-43 is typically a nuclear protein, and its aggregation and cytoplasmic translocation are thought to represent major steps in the pathogenesis of FTLD due to TDP-43 proteinopathy (FTLD-TDP)."
This confirms that TDP-43 aggregation and mislocalization are central to the pathogenesis of FTLD-TDP, a major subtype of frontotemporal dementia.
Tau Proteinopathy
FTLD-tau is characterized by accumulation of hyperphosphorylated tau protein, accounting for approximately 45% of FTD cases. This includes Pick's disease with characteristic Pick bodies. The tau pathology disrupts microtubule function and causes neuronal degeneration primarily in frontal and temporal regions.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
MAPT hgnc:6893 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves MAPT (hgnc:6893). hgnc:6893 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Neuronal Death
Behavioral Changes
Aphasia
Show evidence (1 reference)
PMID:21720721 SUPPORT Human Clinical
"PiD is the least common FTLD-tau characterized by neuronal Pick bodies in a stereotypic neuroanatomical distribution."
This confirms Pick's disease (PiD), with its characteristic Pick bodies, as one of the FTLD-tau subtypes underlying the tau proteinopathy arm of FTD.
FUS Proteinopathy
A minority of FTD cases are tau- and TDP-43-negative. Within that heterogeneous group (which also includes CHMP2B-associated FTLD-UPS), the cases whose inclusions are immunoreactive for FUS (fused in sarcoma) constitute FTLD-FUS, completing the TDP-43 / tau / FUS molecular triad underlying FTD.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
Downstream
Neuronal Death
Behavioral Changes
Aphasia
Show evidence (1 reference)
PMID:21603977 SUPPORT Human Clinical
"the discovery that the pathological changes in atypical FTLD with ubiquitinated inclusions, neuronal intermediate filament inclusion disease, and basophilic inclusion body disease are immunoreactive for the fused in sarcoma (FUS) protein, resulting in the creation of a new molecular subgroup (FTLD-FUS)"
Establishes FTLD-FUS as a distinct, tau/TDP-43-negative molecular subgroup of frontotemporal lobar degeneration.
CHMP2B C-Truncation and Aberrant Endosome Formation
The CHMP2B lesion acts on a different compartment from the three proteinopathies above. The chromosome 3 splice-acceptor mutation and an analogous nonsense mutation both predict a C-truncated CHMP2B, and expressing either in neuroblastoma cells produces large aberrant endosomal structures, so the proposed mechanism is disturbed endosome function in an ESCRT-III subunit rather than aggregation of a cytoplasmic protein. The pathology that follows is ubiquitin- and p62-positive and TDP-43-negative, which is why FTD-3 was reclassified as FTLD with ubiquitin-positive inclusions.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
CHMP2B hgnc:24537 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves CHMP2B (hgnc:24537). hgnc:24537 is a gene from the HUGO Gene Nomenclature Committee.
endosome organization GO:0007032 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal endosome organization (GO:0007032). GO:0007032 is a biological process from the Gene Ontology.
Downstream
Neuronal Death Cortical neuron loss is what the postmortem material from the affected family shows, alongside microvacuolation of layer II and mild gliosis.
Personality Changes The clinical picture the CHMP2B lesion produces opens with subtle personality change and slowly progressive behavioral change, with disinhibition or loss of initiative the commonest presenting symptom.
Show evidence (2 references)
PMID:17956895 SUPPORT In Vitro
"Overexpression of Belgian p.Gln165X in human neuroblastoma SK-N-SH cells showed the formation of large, aberrant endosomal structures that were highly similar to those observed for Danish p.Met178ValfsX2."
The cell-based measurement behind this node: two independently arising C-truncating CHMP2B alleles both produce the same aberrant endosomal morphology.
PMID:17917582 SUPPORT Human Clinical
"The finding of ubiquitin- and p62-positive, TDP-43-negative cytoplasmic inclusions in the hippocampus and neocortex suggests reclassification of the neuropathology of FTD-3 as a unique subtype of frontotemporal lobar degeneration with ubiquitin-positive inclusions that are TDP-43-negative."
Human postmortem material from the chromosome 3 family places this node's pathology outside the tau, TDP-43 and FUS classes, which is the reason it is modeled as a separate node.
Frontal and Temporal Lobe Atrophy
Progressive neuronal loss and atrophy predominantly affecting the frontal and temporal lobes, with patterns varying by genetic subtype. MAPT mutations show temporal predominance, while GRN and C9orf72 mutations may show more variable patterns. This structural degeneration underlies the behavioral and language deficits.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
Downstream
Behavioral Changes
Aphasia
Show evidence (2 references)
PMID:26473392 SUPPORT
"MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy."
This demonstrates the genotype-specific patterns of brain atrophy and their relationship to clinical phenotypes in frontotemporal dementia.
PMID:42390534 SUPPORT Human Clinical
"All VRS yielded higher atrophy in bvFTD than in PPD patients. The Orbitofrontal, the Anterior-Temporal, and the Fronto-Insula scales were the strongest discriminators."
Multicenter study identifying specific atrophy patterns (orbitofrontal, anterior-temporal, fronto-insular regions) as diagnostic biomarkers for distinguishing bvFTD from primary psychiatric disorder using visual rating scales.
Neuronal Death
Progressive loss of neurons in frontal and temporal cortices due to protein aggregation toxicity, leading to brain atrophy and functional decline. The neurodegeneration progresses over years to decades, with biomarker changes detectable up to 30 years before symptom onset in genetic cases.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
Downstream
Frontal and Temporal Lobe Atrophy Accumulated neuron loss is what the macroscopic atrophy is made of, which is why the atrophy node sits downstream of this one rather than beside it.
Dementia Whatever the initiating proteinopathy, the accumulating neuron loss ends in a global dementia; the trajectory is measured in years to decades rather than months.
Show evidence (1 reference)
PMID:30711676 SUPPORT
"We observed that biological changes and intracortical facilitation transmission abnormalities significantly antecede the emergence of clinical symptoms of at least 3 decades."
Supports long presymptomatic neurobiological change in genetic FTD, but does not directly quantify neuronal death in the quoted text.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Frontotemporal Dementia Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

4
Behavioral Changes VERY_FREQUENT Neurological HP:0000708 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Behavioral Changes, annotated with Atypical behavior (HP:0000708). HP:0000708 is a phenotype from the Human Phenotype Ontology.
Prominent behavioral changes including disinhibition, apathy, loss of empathy, compulsive behaviors, and dietary changes. Particularly characteristic of behavioral variant FTD.
Show evidence (1 reference)
PMID:26473392 SUPPORT
"MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy."
This confirms that behavioral disinhibition and repetitive stereotyped behaviors are core clinical features of genetic FTD, particularly in MAPT mutations.
Aphasia VERY_FREQUENT Neurological HP:0002381 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aphasia (HP:0002381). HP:0002381 is a phenotype from the Human Phenotype Ontology.
Progressive language impairment, particularly non-fluent aphasia in GRN mutations and semantic variant primary progressive aphasia. Language deficits may be the presenting feature.
Show evidence (1 reference)
PMID:26473392 SUPPORT
"GRN patients were older at death and more likely to present with non-fluent aphasia."
This demonstrates that non-fluent aphasia is a characteristic presenting feature in patients with GRN mutations causing frontotemporal dementia.
Personality Changes VERY_FREQUENT Neurological HP:0000751 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Personality changes (HP:0000751). HP:0000751 is a phenotype from the Human Phenotype Ontology.
Progressive changes in personality including social inappropriateness, loss of emotional warmth, and altered social cognition. C9orf72 patients may paradoxically appear socially warm despite other behavioral changes.
Show evidence (1 reference)
PMID:26473392 SUPPORT
"They showed more psychotic symptoms and irrational behaviour, yet were more often reported clinically as socially appropriate and warm."
This highlights the complex and sometimes paradoxical personality changes in C9orf72-related FTD, where patients may retain apparent social warmth despite significant behavioral dysfunction.
Dementia VERY_FREQUENT Neurological HP:0000726 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dementia (HP:0000726). HP:0000726 is a phenotype from the Human Phenotype Ontology.
Progressive cognitive decline affecting executive function, social cognition, and behavior, with relatively preserved memory in early stages compared to Alzheimer's disease.
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Genetic Associations

4
MAPT (Mutations cause autosomal dominant FTD with tau pathology)
Gene: MAPT hgnc:6893 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is MAPT (hgnc:6893). hgnc:6893 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (2 references)
PMID:26473392 SUPPORT
"MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy."
This confirms the distinct clinical and anatomical phenotype associated with MAPT mutations in frontotemporal dementia.
PPR:PPR1289994 Preprint · not peer-reviewed SUPPORT Human Clinical
"carriers exhibited pronounced impairments in semantic knowledge and social cognition"
Digital cognitive assessment of 569 Genetic FTD Initiative participants shows MAPT carriers have a semantic-knowledge and social-cognition predominant cognitive profile.
GRN (Mutations cause autosomal dominant FTD with TDP-43 pathology)
Gene: GRN hgnc:4601 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is GRN (hgnc:4601). hgnc:4601 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (3 references)
PMID:26473392 SUPPORT
"GRN patients were older at death and more likely to present with non-fluent aphasia."
This demonstrates the characteristic clinical presentation of GRN-related FTD with language deficits.
PMID:30711676 SUPPORT
"Presymptomatic carriers of GRN and C9orf72 mutations, the most frequent genetic causes of frontotemporal lobar degeneration, represent the optimal target population for the development of disease-modifying drugs."
This confirms GRN as one of the two most common genetic causes of FTD.
PPR:PPR1289994 Preprint · not peer-reviewed SUPPORT Human Clinical
"carriers demonstrated marked deficits in executive function and processing speed, particularly at symptomatic stages"
Digital cognitive assessment of 569 Genetic FTD Initiative participants shows GRN carriers have an executive-function and processing-speed predominant cognitive profile.
C9orf72 (Hexanucleotide repeat expansion causes autosomal dominant FTD, often with ALS)
Gene: C9orf72 hgnc:28337 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is C9orf72 (hgnc:28337). hgnc:28337 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (3 references)
PMID:26473392 SUPPORT
"C9orf72 patients alone showed a co-occurrence of ALS. They showed more psychotic symptoms and irrational behaviour, yet were more often reported clinically as socially appropriate and warm."
This highlights the distinctive clinical features of C9orf72-related FTD including the frequent association with ALS and unique behavioral profile.
PMID:30711676 SUPPORT
"Presymptomatic carriers of GRN and C9orf72 mutations, the most frequent genetic causes of frontotemporal lobar degeneration, represent the optimal target population for the development of disease-modifying drugs."
This confirms C9orf72 as one of the most common genetic causes of FTD.
PPR:PPR1289994 Preprint · not peer-reviewed SUPPORT Human Clinical
"mutation carriers showed the earliest and broadest deficits across all cognitive domains"
Digital cognitive assessment of 569 Genetic FTD Initiative participants shows C9orf72 carriers have the earliest and broadest cognitive impairment of the three genetic groups.
CHMP2B (Heterozygous C-truncating variants cause autosomal dominant FTD-3)
Gene: CHMP2B (charged multivesicular body protein 2B, ESCRT-III subunit) hgnc:24537 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is CHMP2B (charged multivesicular body protein 2B, ESCRT-III subunit), annotated with CHMP2B (hgnc:24537). hgnc:24537 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (2 references)
PMID:16041373 SUPPORT Human Clinical
"Here we identify a mutation in CHMP2B, encoding a component of the endosomal ESCRTIII complex, and show that it results in aberrant mRNA splicing in tissue samples from affected members of this family."
Establishes the gene-disease assertion for CHMP2B in the chromosome 3-linked FTD family, and the splicing consequence of the founding allele.
PMID:20301378 SUPPORT Human Clinical
"CHMP2B-FTD-ALS is inherited in an autosomal dominant manner. Penetrance is age dependent and appears to be nearly complete."
GeneReviews gives the inheritance and penetrance for the CHMP2B form, which is what this genetic record asserts.
💊

Medical Actions

2
Symptomatic Management
Action: Symptomatic TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Symptomatic Therapy (NCIT:C170740). NCIT:C170740 is a clinical intervention from the NCI Thesaurus. NCIT:C170740
No disease-modifying treatments currently available. Management focuses on behavioral symptoms with selective serotonin reuptake inhibitors for compulsive behaviors and agitation, and non-pharmacological approaches including behavioral interventions and caregiver support.
Speech and Language Therapy
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Speech therapy interventions for patients with language-variant FTD to maintain communication abilities and quality of life for as long as possible.
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Biochemical Markers

1
NEFL-C1QL2 Projection Neuron Plasma Proteomic Age Gap (Elevated)
Context: Blood-based cell-type-specific aging clock. Plasma proteins are mapped to their putative cell of origin using Human Protein Atlas single-cell transcriptomic data, and a machine-learning model estimates that cell type's biological age; the age gap is the difference between that estimate and chronological age. "Extreme" agers are those in the upper tail of the age-gap distribution.
Pathograph Readouts
Predicts Neuronal Death Positive Prognostic
An elevated NEFL-C1QL2 projection neuron age gap predicts incident frontotemporal dementia. The NEFL component is an established axonal-injury marker in FTD, which is what anchors the readout to the neurodegeneration arm rather than leaving it an unanchored risk score.
Show evidence (1 reference)
PMID:42297981 SUPPORT Human Clinical
"extreme aging in NEFL-C1QL2 projection neurons demonstrated the strongest prognostic value"
Supports treating the age gap as a prognostic readout anticipating clinical frontotemporal dementia.
Correlates With Frontal and Temporal Lobe Atrophy Positive Prognostic
C1QL2 is enriched in the temporo-limbic structures that frontotemporal lobar degeneration targets, which is the authors' basis for reading this signature against the regional atrophy arm. This is a regional-expression argument, not a measured correlation with imaged atrophy.
Show evidence (1 reference)
PMID:42297981 SUPPORT Human Clinical
"C1QL2 is a synaptic organizer known to be prominent in temporo-limbic structures vulnerable to frontotemporal lobar degeneration"
Gives the regional-vulnerability rationale connecting the signature to the frontal and temporal atrophy node.
Show evidence (2 references)
PMID:42297981 SUPPORT Human Clinical
"extreme aging in NEFL-C1QL2 projection neurons demonstrated the strongest prognostic value"
Establishes this signature as the leading cellular-aging predictor of incident frontotemporal dementia among the cell types tested.
PMID:42297981 SUPPORT Human Clinical
"NEFL is a widely recognized biomarker of axonal injury, often markedly raised in FTD, while C1QL2 is a synaptic organizer known to be prominent in temporo-limbic structures vulnerable to frontotemporal lobar degeneration"
The authors' justification for both the relabelling and the disease relevance: one marker of axonal injury already established in FTD, one synaptic gene enriched in the regions FTLD targets.
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Diagnosis

3
Montreal Cognitive Assessment
Brief cognitive screening instrument. A validation study in behavioral-variant frontotemporal dementia found it more accurate than the MMSE for that syndrome, and in genetic frontotemporal dementia cohorts it distinguished presymptomatic pathogenic variant carriers from controls where the MMSE did not.
MoCA LOINC:72133-2 Logical Observation Identifiers Names and Codes (LOINC)
Reference Ranges
Total score [MoCA] (MoCA validation study for behavioral-variant frontotemporal dementia, three matched subgroups of 50 (bv-FTD, Alzheimer disease, healthy adults))
Below 17 (screen positive for bv-FTD) (< 17 {score}) 17 or above (≥ 17 {score})
The abstract states the cut-off as "With a cutoff below 17 points"; a score below 17 falls in the positive band, which the half-open bands reproduce exactly. The cut-off was derived in the behavioral variant only.
Show evidence (1 reference)
PMID:22859702 SUPPORT PRIMARY RESULT Human Clinical
"With a cutoff below 17 points, the MoCA results for sensitivity, specificity, positive predictive value, negative predictive value, and classification accuracy were significantly superior to those of the MMSE."
States the MoCA cut-off for behavioral-variant frontotemporal dementia.
Copyright © Tina Brosseau for Center for Diagnosis & Research on Alzheimer's disease (CEDRA). Used with permission. The instrument is bound at its LOINC panel code and the cut-off at its total-score code. The instrument's items are not reproduced in this entry; only published thresholds are recorded. The genetic frontotemporal dementia study (PMID:39951678) reports group medians and discriminative accuracy but no cut-off, so it carries no range.
Show evidence (2 references)
PMID:22859702 SUPPORT PRIMARY RESULT Human Clinical
"The MoCA is a sensitive and accurate instrument for screening the patients with bv-FTD and represents a better option than the MMSE."
Supports the MoCA as a screening instrument for behavioral-variant frontotemporal dementia.
PMID:39951678 SUPPORT PRIMARY RESULT Human Clinical
"MoCA demonstrated superior discriminative ability compared with MMSE (MoCA area under the curve [AUC] = 0.87, 95% CI 0.81-0.94; MMSE AUC = 0.80, 95% CI 0.72-0.89)."
Supports the MoCA as the better screening instrument in genetic frontotemporal dementia.
Mini-Mental State Examination
Widely used cognitive screening instrument, recorded here because the frontotemporal dementia literature compares the MoCA against it and uses it to track severity. It is less sensitive in frontotemporal dementia than the MoCA, and in primary progressive aphasia its dependence on language overestimates dementia severity.
MMSE LOINC:72107-6 Logical Observation Identifiers Names and Codes (LOINC)
Copyright © Vicki King for Psychological Assessment Resources. Used with permission. No reference range is recorded: no cited source states a frontotemporal dementia cut-off or severity scheme for the MMSE. A PubMed search for mini-mental[ti] frontotemporal[ti] returned comparisons with the MoCA and studies of MMSE change over time, none stating a cut-off, and MMSE[ti] frontotemporal[ti] cut-off returned no records. The instrument's items are not reproduced in this entry.
Show evidence (2 references)
PMID:39951678 SUPPORT PRIMARY RESULT Human Clinical
"MoCA distinguished between presymptomatic carriers and controls (median MoCA 28, 95% CI 27.0-29.0), but MMSE did not."
Records the MMSE's insensitivity to the earliest stage of genetic frontotemporal dementia.
PMID:18166606 SUPPORT PRIMARY RESULT Human Clinical
"Results suggest that the MMSE score, heavily dependent on language skill, overestimates dementia severity in PPA patients. However, the score may be a more accurate measure of functional impairment in bvFTD due to the influence of their executive function and attentional deficits on MMSE performance."
Describes how MMSE severity readings differ between the behavioral and aphasic variants.
Clinical Dementia Rating
Global dementia staging instrument developed for Alzheimer's disease. In frontotemporal dementia it is used with two added domains for behaviour and language, as the CDR plus National Alzheimer's Coordinating Centre Behaviour and Language Domains (CDR plus NACC FTLD), whose global score grades disease stage in genetic frontotemporal dementia cohorts.
CDR LOINC:72088-8 Logical Observation Identifiers Names and Codes (LOINC)
Copyright © Washington University Charles F. and Joanne Knight Alzheimer's Disease Research Center (Knight ADRC). Used with permission. The binding is the original CDR panel, the only CDR code LOINC carries. A search of the LOINC 2.83 table (the Tuva Project extract pinned in data/loinc/MANIFEST.yaml) for "CDR", "dementia rating", "FTLD" and "frontotemporal", and of the Monarch KG for "FTLD" and "frontotemporal dementia rating", found no code for the CDR plus NACC FTLD or its global or sum-of-boxes scores, so no stage bands are recorded. The instrument's items are not reproduced in this entry.
Show evidence (2 references)
PMID:38152057 SUPPORT PRIMARY RESULT Human Clinical
"This study validated the Japanese version of the CDR® plus NACC FTLD with good reliability, validity, and responsiveness."
The CDR extended with the NACC behaviour and language domains is a validated staging instrument in frontotemporal dementia.
PMID:39951678 SUPPORT Human Clinical
"Grouping was based on the global CDR-plus-NACC-FTLD score."
The global CDR plus NACC FTLD score is used to stage genetic frontotemporal dementia carriers.
📊

Related Datasets

1
Expression data from postmortem human brain samples with and without FTLD-U geo:GSE13162
Microarray expression profiling of frontal cortex, hippocampus, and cerebellum from FTLD-U and control brains.
human MICROARRAY n=56
brain tissue UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this dataset samples this sample type This dataset samples brain tissue, annotated with brain (UBERON:0000955). UBERON:0000955 is a sample type from the Uberon multi-species anatomy ontology.
Conditions: frontotemporal lobar degeneration with ubiquitin-positive inclusions control brain tissue
Includes 31 FTLD-U and 25 control samples.
{ }

Source YAML

click to show 
name: Frontotemporal Dementia
creation_date: '2025-12-23T16:19:20Z'
description: >
  Frontotemporal Dementia (FTD) is a group of neurodegenerative disorders characterized
  by progressive deterioration of the frontal and temporal lobes of the brain. It
  presents
  with prominent changes in personality, behavior, and/or language, typically with
  onset
  before age 65. FTD is associated with abnormal accumulation of tau, TDP-43, or (less commonly) FUS proteins.
category: Complex
disease_term:
  preferred_term: frontotemporal dementia
  term:
    id: MONDO:0017276
    label: frontotemporal dementia
parents:
- Dementia
- Neurodegenerative Disease
has_subtypes:
- name: Behavioral Variant FTD
  display_name: Behavioral Variant Frontotemporal Dementia (bvFTD)
  subtype_term:
    preferred_term: behavioral variant of frontotemporal dementia
    term:
      id: MONDO:0017160
      label: behavioral variant of frontotemporal dementia
  description: >
    The most common clinical presentation of FTD, characterized by progressive
    behavioral and personality change with frontal-lobe-predominant atrophy.
    Preferentially associated with MAPT mutations, which show earlier onset,
    prominent disinhibition, stereotyped behaviors, and temporal-predominant
    atrophy; also a common presentation in C9orf72 carriers, who additionally
    show psychotic symptoms and paradoxical social warmth.
  genes:
  - preferred_term: MAPT
    term:
      id: hgnc:6893
      label: MAPT
  - preferred_term: C9orf72
    term:
      id: hgnc:28337
      label: C9orf72
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy.
    explanation: Confirms MAPT mutations preferentially produce the behavioral-variant clinical phenotype with early disinhibition and temporal-predominant atrophy.
- name: Semantic Variant PPA
  display_name: Semantic Variant Primary Progressive Aphasia (svPPA / Semantic Dementia)
  subtype_term:
    preferred_term: semantic dementia
    term:
      id: MONDO:0010857
      label: semantic dementia
  description: >
    A language-predominant FTD syndrome characterized by progressive loss of
    semantic knowledge (anomia, impaired word comprehension, surface dyslexia)
    with anterior temporal lobe degeneration. One of the three canonical PPA
    variants (with nonfluent/agrammatic and logopenic) defined by international
    consensus criteria. Typically sporadic with underlying TDP-43 type C
    pathology, showing weaker association with the three major FTD genes than
    the behavioral or nonfluent variants.
  evidence:
  - reference: PMID:21325651
    reference_title: "Classification of primary progressive aphasia and its variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Criteria for the 3 variants of PPA--nonfluent/agrammatic, semantic, and logopenic--were developed by an international group of PPA investigators who convened on 3 occasions to operationalize earlier published clinical descriptions for PPA subtypes.
    explanation: Establishes semantic variant PPA as one of the three internationally standardized clinical PPA subtypes within the FTD spectrum.
- name: Nonfluent Variant PPA
  display_name: Nonfluent/Agrammatic Variant Primary Progressive Aphasia (nfvPPA)
  subtype_term:
    preferred_term: progressive non-fluent aphasia
    term:
      id: MONDO:0015059
      label: progressive non-fluent aphasia
  description: >
    A language-predominant FTD syndrome characterized by agrammatism, laborious
    non-fluent speech, and apraxia of speech, with relatively preserved
    comprehension. Preferentially associated with GRN mutations (older age at
    death, TDP-43 type A pathology) and also seen with C9orf72 expansions;
    non-fluent aphasia links to TDP-43 type A pathology in both groups.
  genes:
  - preferred_term: GRN
    term:
      id: hgnc:4601
      label: GRN
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: GRN patients were older at death and more likely to present with non-fluent aphasia.
    explanation: Confirms GRN mutations preferentially produce the nonfluent/agrammatic-aphasia clinical phenotype.
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Non-fluent aphasia was linked to TDP subtype A in both GRN and C9orf72 cases and ALS with subtype B.
    explanation: Links the nonfluent-aphasia phenotype to TDP-43 type A pathology across both GRN- and C9orf72-associated FTD.
- name: FTD with Motor Neuron Disease
  display_name: Frontotemporal Dementia with Motor Neuron Disease (FTD-MND / FTD-ALS)
  subtype_term:
    preferred_term: frontotemporal dementia with motor neuron disease
    term:
      id: MONDO:0017161
      label: frontotemporal dementia with motor neuron disease
  description: >
    FTD co-occurring with clinical motor neuron disease/ALS, almost exclusively
    linked to the C9orf72 hexanucleotide repeat expansion. C9orf72-associated
    ALS-FTD cases show more psychotic symptoms and paradoxical social warmth
    than MAPT- or GRN-associated FTD, and ALS co-occurrence links to TDP-43
    type B pathology.
  genes:
  - preferred_term: C9orf72
    term:
      id: hgnc:28337
      label: C9orf72
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: C9orf72 patients alone showed a co-occurrence of ALS.
    explanation: Confirms that ALS co-occurrence in this FTD cohort was exclusive to C9orf72 mutation carriers.
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Non-fluent aphasia was linked to TDP subtype A in both GRN and C9orf72 cases and ALS with subtype B.
    explanation: Links ALS co-occurrence in C9orf72-associated FTD to TDP-43 type B pathology.
- name: FTD3
  display_name: FTD3 (CHMP2B-related frontotemporal dementia-amyotrophic lateral sclerosis)
  subtype_term:
    preferred_term: CHMP2B-related frontotemporal dementia-amyotrophic lateral sclerosis
    term:
      id: MONDO:0010936
      label: frontotemporal dementia and/or amyotrophic lateral sclerosis 7
  description: >
    The chromosome 3-linked form, defined by heterozygous CHMP2B variants and
    originally delineated in a large Danish pedigree. It is a molecular subtype
    rather than a clinical one, and it is the reason this entry's molecular
    classification is not exhausted by tau, TDP-43 and FUS: its inclusions are
    ubiquitin- and p62-positive but TDP-43-negative, which is the FTLD-UPS class
    named in the FUS Proteinopathy node's description. Presentation is usually
    FTD, with ALS features in a subset, and MONDO files the class under both
    behavioral variant FTD and familial ALS; it is kept here rather than at
    the ALS entry because the dementia phenotype is the usual one.
  genes:
  - preferred_term: CHMP2B
    term:
      id: hgnc:24537
      label: CHMP2B
  evidence:
  - reference: PMID:20301378
    reference_title: "CHMP2B-Related Frontotemporal Dementia-Amyotrophic Lateral Sclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      CHMP2B-related frontotemporal dementia (FTD)-amyotrophic lateral sclerosis
      (ALS) is characterized most frequently by FTD with subtle personality
      changes and slowly progressive behavioral changes, dysexecutive syndrome,
      and language disturbances.
    explanation: >-
      GeneReviews establishes that the CHMP2B entity presents most frequently as
      frontotemporal dementia, which is what places this subtype on this entry
      rather than on the ALS entry.
  - reference: PMID:16041373
    reference_title: "Mutations in the endosomal ESCRTIII-complex subunit CHMP2B in frontotemporal dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We have previously reported a large Danish pedigree with autosomal
      dominant frontotemporal dementia (FTD) linked to chromosome 3 (FTD3). Here
      we identify a mutation in CHMP2B, encoding a component of the endosomal
      ESCRTIII complex, and show that it results in aberrant mRNA splicing in
      tissue samples from affected members of this family.
    explanation: >-
      The founding gene-disease report: it ties the chromosome 3-linked FTD3
      locus to a CHMP2B splicing mutation, which is this subtype's defining
      genotype.
pathophysiology:
- name: TDP-43 Proteinopathy
  description: >
    TAR DNA-binding protein of 43 kDa (TDP-43) is the main ubiquitinated protein
    in tau-negative frontotemporal lobar degeneration (FTLD-TDP), accounting for
    over 50% of FTD cases. TDP-43 is typically a nuclear protein, and its aggregation
    and cytoplasmic translocation are thought to represent major pathogenic steps.
    The abnormal accumulation leads to neuronal dysfunction and death.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  genes:
  - preferred_term: GRN
    term:
      id: hgnc:4601
      label: GRN
  - preferred_term: C9orf72
    term:
      id: hgnc:28337
      label: C9orf72
  downstream:
  - target: Neuronal Death
  - target: Behavioral Changes
  - target: Aphasia
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: MAPT cases had tau and GRN and C9orf72, with one exception, TDP-43 pathology.
    explanation: >-
      Clinico-pathological correlation in a gene-positive cohort assigns GRN and
      C9orf72 carriers to TDP-43 pathology and MAPT carriers to tau, which is
      what places these two genes on this node and MAPT on the tau node.
  - reference: PMID:19664364
    reference_title: "TDP-43 and frontotemporal dementia."
    supports: SUPPORT
    snippet: TDP-43 is typically a nuclear protein, and its aggregation and cytoplasmic translocation are thought to represent major steps in the pathogenesis of FTLD due to TDP-43 proteinopathy (FTLD-TDP).
    explanation: This confirms that TDP-43 aggregation and mislocalization are central to the pathogenesis of FTLD-TDP, a major subtype of frontotemporal dementia.
- name: Tau Proteinopathy
  description: >
    FTLD-tau is characterized by accumulation of hyperphosphorylated tau protein,
    accounting for approximately 45% of FTD cases. This includes Pick's disease
    with characteristic Pick bodies. The tau pathology disrupts microtubule function
    and causes neuronal degeneration primarily in frontal and temporal regions.
  genes:
  - preferred_term: MAPT
    term:
      id: hgnc:6893
      label: MAPT
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  downstream:
  - target: Neuronal Death
  - target: Behavioral Changes
  - target: Aphasia
  evidence:
  - reference: PMID:21720721
    reference_title: "Neuropathology of frontotemporal lobar degeneration-tau (FTLD-tau)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: PiD is the least common FTLD-tau characterized by neuronal Pick bodies in a stereotypic neuroanatomical distribution.
    explanation: This confirms Pick's disease (PiD), with its characteristic Pick bodies, as one of the FTLD-tau subtypes underlying the tau proteinopathy arm of FTD.
- name: FUS Proteinopathy
  description: >
    A minority of FTD cases are tau- and TDP-43-negative. Within that
    heterogeneous group (which also includes CHMP2B-associated FTLD-UPS), the
    cases whose inclusions are immunoreactive for FUS (fused in sarcoma)
    constitute FTLD-FUS, completing the TDP-43 / tau / FUS molecular triad
    underlying FTD.
  biological_scale: MOLECULAR
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  downstream:
  - target: Neuronal Death
  - target: Behavioral Changes
  - target: Aphasia
  evidence:
  - reference: PMID:21603977
    reference_title: "Novel types of frontotemporal lobar degeneration: beyond tau and TDP-43."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the discovery that the pathological changes in atypical FTLD with ubiquitinated inclusions, neuronal intermediate filament inclusion disease, and basophilic inclusion body disease are immunoreactive for the fused in sarcoma (FUS) protein, resulting in the creation of a new molecular subgroup (FTLD-FUS)
    explanation: Establishes FTLD-FUS as a distinct, tau/TDP-43-negative molecular subgroup of frontotemporal lobar degeneration.
- name: CHMP2B C-Truncation and Aberrant Endosome Formation
  description: >
    The CHMP2B lesion acts on a different compartment from the three
    proteinopathies above. The chromosome 3 splice-acceptor mutation and an
    analogous nonsense mutation both predict a C-truncated CHMP2B, and expressing
    either in neuroblastoma cells produces large aberrant endosomal structures,
    so the proposed mechanism is disturbed endosome function in an ESCRT-III
    subunit rather than aggregation of a cytoplasmic protein. The pathology that
    follows is ubiquitin- and p62-positive and TDP-43-negative, which is why
    FTD-3 was reclassified as FTLD with ubiquitin-positive inclusions.
  biological_scale: CELLULAR
  genes:
  - preferred_term: CHMP2B
    term:
      id: hgnc:24537
      label: CHMP2B
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: endosome organization
    term:
      id: GO:0007032
      label: endosome organization
    modifier: ABNORMAL
  evidence:
  - reference: PMID:17956895
    reference_title: "CHMP2B C-truncating mutations in frontotemporal lobar degeneration are associated with an aberrant endosomal phenotype in vitro."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Overexpression of Belgian p.Gln165X in human neuroblastoma SK-N-SH cells
      showed the formation of large, aberrant endosomal structures that were
      highly similar to those observed for Danish p.Met178ValfsX2.
    explanation: >-
      The cell-based measurement behind this node: two independently arising
      C-truncating CHMP2B alleles both produce the same aberrant endosomal
      morphology.
  - reference: PMID:17917582
    reference_title: "A reassessment of the neuropathology of frontotemporal dementia linked to chromosome 3."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The finding of ubiquitin- and p62-positive, TDP-43-negative cytoplasmic
      inclusions in the hippocampus and neocortex suggests reclassification of
      the neuropathology of FTD-3 as a unique subtype of frontotemporal lobar
      degeneration with ubiquitin-positive inclusions that are TDP-43-negative.
    explanation: >-
      Human postmortem material from the chromosome 3 family places this node's
      pathology outside the tau, TDP-43 and FUS classes, which is the reason it
      is modeled as a separate node.
  downstream:
  - target: Neuronal Death
    description: >-
      Cortical neuron loss is what the postmortem material from the affected
      family shows, alongside microvacuolation of layer II and mild gliosis.
    evidence:
    - reference: PMID:17917582
      reference_title: "A reassessment of the neuropathology of frontotemporal dementia linked to chromosome 3."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Microscopy showed loss of cortical neurons, microvacuolation of layer II,
        mild gliosis, and demyelination of the deep white matter.
      explanation: >-
        Reports the cortical neuron loss this edge asserts, in the same four
        autopsied family members that carry the inclusion pathology.
  - target: Personality Changes
    description: >-
      The clinical picture the CHMP2B lesion produces opens with subtle
      personality change and slowly progressive behavioral change, with
      disinhibition or loss of initiative the commonest presenting symptom.
    evidence:
    - reference: PMID:20301378
      reference_title: "CHMP2B-Related Frontotemporal Dementia-Amyotrophic Lateral Sclerosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        CHMP2B-related frontotemporal dementia (FTD)-amyotrophic lateral
        sclerosis (ALS) is characterized most frequently by FTD with subtle
        personality changes and slowly progressive behavioral changes,
        dysexecutive syndrome, and language disturbances.
      explanation: >-
        GeneReviews names the personality change as a leading feature of the
        CHMP2B entity, which is the edge from this node to that phenotype.
    - reference: PMID:20301378
      reference_title: "CHMP2B-Related Frontotemporal Dementia-Amyotrophic Lateral Sclerosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Disinhibition or loss of initiative is the most common presenting symptom.
      explanation: >-
        Supports the ranking this edge's description makes. The preceding item
        establishes personality and behavioral change as the leading features but
        ranks nothing within them, so this sentence is what carries the claim that
        disinhibition or loss of initiative is the commonest presenting symptom.
- name: Frontal and Temporal Lobe Atrophy
  description: >
    Progressive neuronal loss and atrophy predominantly affecting the frontal and
    temporal lobes, with patterns varying by genetic subtype. MAPT mutations show
    temporal predominance, while GRN and C9orf72 mutations may show more variable
    patterns. This structural degeneration underlies the behavioral and language deficits.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  downstream:
  - target: Behavioral Changes
  - target: Aphasia
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy.
    explanation: This demonstrates the genotype-specific patterns of brain atrophy and their relationship to clinical phenotypes in frontotemporal dementia.
  - reference: PMID:42390534
    reference_title: "Visual rating scales of atrophy differentiate sporadic behavioral variant frontotemporal dementia from primary psychiatric disorder: DIPPA study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: All VRS yielded higher atrophy in bvFTD than in PPD patients. The Orbitofrontal, the Anterior-Temporal, and the Fronto-Insula scales were the strongest discriminators.
    explanation: Multicenter study identifying specific atrophy patterns (orbitofrontal, anterior-temporal, fronto-insular regions) as diagnostic biomarkers for distinguishing bvFTD from primary psychiatric disorder using visual rating scales.
- name: Neuronal Death
  description: >
    Progressive loss of neurons in frontal and temporal cortices due to protein
    aggregation toxicity, leading to brain atrophy and functional decline. The
    neurodegeneration progresses over years to decades, with biomarker changes
    detectable up to 30 years before symptom onset in genetic cases.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:30711676
    reference_title: "Clinical and biomarker changes in presymptomatic genetic frontotemporal dementia."
    supports: SUPPORT
    snippet: We observed that biological changes and intracortical facilitation transmission abnormalities significantly antecede the emergence of clinical symptoms of at least 3 decades.
    explanation: Supports long presymptomatic neurobiological change in genetic FTD, but does not directly quantify neuronal death in the quoted text.
  downstream:
  - target: Frontal and Temporal Lobe Atrophy
    description: >-
      Accumulated neuron loss is what the macroscopic atrophy is made of, which
      is why the atrophy node sits downstream of this one rather than beside it.
    evidence:
    - reference: PMID:17917582
      reference_title: "A reassessment of the neuropathology of frontotemporal dementia linked to chromosome 3."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Gross examination revealed generalized cortical atrophy that was most
        severe in frontal and temporal cortices.
      explanation: >-
        Pairs the gross frontotemporal atrophy with the microscopic cortical
        neuron loss reported in the same autopsy series, which is the direction
        of this edge.
  - target: Dementia
    description: >-
      Whatever the initiating proteinopathy, the accumulating neuron loss ends in
      a global dementia; the trajectory is measured in years to decades rather
      than months.
    evidence:
    - reference: PMID:20301678
      reference_title: "MAPT-Related Frontotemporal Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        MAPT-FTD is a progressive disorder that commonly ends with a relatively
        global dementia in which some affected individuals become mute.
      explanation: >-
        GeneReviews states the endpoint of the progressive degeneration for the
        MAPT form; the quote is about one genetic subtype, so the edge to a
        disease-level dementia phenotype takes one generalizing step.
      directness: INDIRECT
phenotypes:
- category: Neurological
  name: Behavioral Changes
  phenotype_term:
    preferred_term: Behavioral Changes
    term:
      id: HP:0000708
      label: Atypical behavior
  frequency: VERY_FREQUENT
  diagnostic: true
  notes: Prominent behavioral changes including disinhibition, apathy, loss of empathy, compulsive behaviors, and dietary changes. Particularly characteristic of behavioral variant FTD.
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy.
    explanation: This confirms that behavioral disinhibition and repetitive stereotyped behaviors are core clinical features of genetic FTD, particularly in MAPT mutations.
- category: Neurological
  name: Aphasia
  frequency: VERY_FREQUENT
  diagnostic: true
  notes: Progressive language impairment, particularly non-fluent aphasia in GRN mutations and semantic variant primary progressive aphasia. Language deficits may be the presenting feature.
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: GRN patients were older at death and more likely to present with non-fluent aphasia.
    explanation: This demonstrates that non-fluent aphasia is a characteristic presenting feature in patients with GRN mutations causing frontotemporal dementia.
  phenotype_term:
    preferred_term: Aphasia
    term:
      id: HP:0002381
      label: Aphasia
- category: Neurological
  name: Personality Changes
  frequency: VERY_FREQUENT
  diagnostic: true
  notes: Progressive changes in personality including social inappropriateness, loss of emotional warmth, and altered social cognition. C9orf72 patients may paradoxically appear socially warm despite other behavioral changes.
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: They showed more psychotic symptoms and irrational behaviour, yet were more often reported clinically as socially appropriate and warm.
    explanation: This highlights the complex and sometimes paradoxical personality changes in C9orf72-related FTD, where patients may retain apparent social warmth despite significant behavioral dysfunction.
  phenotype_term:
    preferred_term: Personality changes
    term:
      id: HP:0000751
      label: Personality changes
- category: Neurological
  name: Dementia
  frequency: VERY_FREQUENT
  diagnostic: true
  notes: Progressive cognitive decline affecting executive function, social cognition, and behavior, with relatively preserved memory in early stages compared to Alzheimer's disease.
  phenotype_term:
    preferred_term: Dementia
    term:
      id: HP:0000726
      label: Dementia
biochemical:
- name: NEFL-C1QL2 Projection Neuron Plasma Proteomic Age Gap
  biomarker_term:
    preferred_term: NEFL-C1QL2 projection neuron plasma proteomic aging clock (age gap)
    term:
      id: NCIT:C97139
      label: Proteomic Profile
  presence: Elevated
  context: >-
    Blood-based cell-type-specific aging clock. Plasma proteins are mapped to
    their putative cell of origin using Human Protein Atlas single-cell
    transcriptomic data, and a machine-learning model estimates that cell type's
    biological age; the age gap is the difference between that estimate and
    chronological age. "Extreme" agers are those in the upper tail of the age-gap
    distribution.
  cell_types:
  - preferred_term: NEFL-C1QL2 projection neuron
    term:
      id: CL:0000540
      label: neuron
  notes: >-
    Read the cell-type label carefully. The Human Protein Atlas catalogues this
    population as "horizontal cell", a retinal interneuron type; the authors
    renamed it NEFL-C1QL2 projection neuron because the two defining transcripts
    point at a projection-neuron identity rather than a retinal one. Curated
    under the authors' relabelling, with CL:0000540 neuron as the only defensible
    binding - there is no CL term for this population, and binding it to the
    retinal horizontal cell would import an assignment the authors explicitly
    rejected. This makes the entry a worked example of the probabilistic
    protein-to-cell-type mapping being the weakest link in these clocks. It was
    the strongest cellular-aging predictor of incident frontotemporal dementia
    (HR 3.03, 95% CI 2.47-3.72), followed by microglia (HR 2.84, 95% CI
    2.33-3.47), and also the strongest cross-sectional association with
    prevalent FTD in the GNPC cohort (n = 199 FTD cases).
  evidence:
  - reference: PMID:42297981
    reference_title: "Plasma proteomic signatures of cellular aging predict human disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: extreme aging in NEFL-C1QL2 projection neurons demonstrated the strongest prognostic value
    explanation: >-
      Establishes this signature as the leading cellular-aging predictor of
      incident frontotemporal dementia among the cell types tested.
  - reference: PMID:42297981
    reference_title: "Plasma proteomic signatures of cellular aging predict human disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: NEFL is a widely recognized biomarker of axonal injury, often markedly raised in FTD, while C1QL2 is a synaptic organizer known to be prominent in temporo-limbic structures vulnerable to frontotemporal lobar degeneration
    explanation: >-
      The authors' justification for both the relabelling and the disease
      relevance: one marker of axonal injury already established in FTD, one
      synaptic gene enriched in the regions FTLD targets.
  readouts:
  - target: Neuronal Death
    relationship: PREDICTS
    direction: POSITIVE
    endpoint_context: PROGNOSTIC
    interpretation: >-
      An elevated NEFL-C1QL2 projection neuron age gap predicts incident
      frontotemporal dementia. The NEFL component is an established axonal-injury
      marker in FTD, which is what anchors the readout to the neurodegeneration
      arm rather than leaving it an unanchored risk score.
    evidence:
    - reference: PMID:42297981
      reference_title: "Plasma proteomic signatures of cellular aging predict human disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: extreme aging in NEFL-C1QL2 projection neurons demonstrated the strongest prognostic value
      explanation: >-
        Supports treating the age gap as a prognostic readout anticipating
        clinical frontotemporal dementia.
  - target: Frontal and Temporal Lobe Atrophy
    relationship: CORRELATES_WITH
    direction: POSITIVE
    endpoint_context: PROGNOSTIC
    interpretation: >-
      C1QL2 is enriched in the temporo-limbic structures that frontotemporal
      lobar degeneration targets, which is the authors' basis for reading this
      signature against the regional atrophy arm. This is a regional-expression
      argument, not a measured correlation with imaged atrophy.
    evidence:
    - reference: PMID:42297981
      reference_title: "Plasma proteomic signatures of cellular aging predict human disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: C1QL2 is a synaptic organizer known to be prominent in temporo-limbic structures vulnerable to frontotemporal lobar degeneration
      explanation: >-
        Gives the regional-vulnerability rationale connecting the signature to
        the frontal and temporal atrophy node.
genetic:
- name: MAPT
  gene_term:
    preferred_term: MAPT
    term:
      id: hgnc:6893
      label: MAPT
  association: Mutations cause autosomal dominant FTD with tau pathology
  notes: Microtubule-associated protein tau gene on chromosome 17q21. Mutations lead to FTLD-tau pathology. Patients show earlier onset, prominent behavioral disinhibition, stereotyped behaviors, and temporal lobe predominance of atrophy. On digital cognitive assessment, MAPT carriers show a semantic-knowledge and social-cognition predominant profile.
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy.
    explanation: This confirms the distinct clinical and anatomical phenotype associated with MAPT mutations in frontotemporal dementia.
  - reference: PPR:PPR1289994
    reference_title: "The Ignite app detects early cognitive impairment and tracks disease severity in genetic frontotemporal dementia"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "carriers exhibited pronounced impairments in semantic knowledge and social cognition"
    explanation: Digital cognitive assessment of 569 Genetic FTD Initiative participants shows MAPT carriers have a semantic-knowledge and social-cognition predominant cognitive profile.
- name: GRN
  gene_term:
    preferred_term: GRN
    term:
      id: hgnc:4601
      label: GRN
  association: Mutations cause autosomal dominant FTD with TDP-43 pathology
  notes: Progranulin gene on chromosome 17q21. Haploinsufficiency leads to FTLD-TDP pathology. Patients more likely to present with non-fluent aphasia and are older at symptom onset. GRN and C9orf72 are the most frequent genetic causes. On digital cognitive assessment, GRN carriers show an executive-function and processing-speed predominant profile, most marked at symptomatic stages.
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: GRN patients were older at death and more likely to present with non-fluent aphasia.
    explanation: This demonstrates the characteristic clinical presentation of GRN-related FTD with language deficits.
  - reference: PMID:30711676
    reference_title: "Clinical and biomarker changes in presymptomatic genetic frontotemporal dementia."
    supports: SUPPORT
    snippet: Presymptomatic carriers of GRN and C9orf72 mutations, the most frequent genetic causes of frontotemporal lobar degeneration, represent the optimal target population for the development of disease-modifying drugs.
    explanation: This confirms GRN as one of the two most common genetic causes of FTD.
  - reference: PPR:PPR1289994
    reference_title: "The Ignite app detects early cognitive impairment and tracks disease severity in genetic frontotemporal dementia"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "carriers demonstrated marked deficits in executive function and processing speed, particularly at symptomatic stages"
    explanation: Digital cognitive assessment of 569 Genetic FTD Initiative participants shows GRN carriers have an executive-function and processing-speed predominant cognitive profile.
- name: C9orf72
  gene_term:
    preferred_term: C9orf72
    term:
      id: hgnc:28337
      label: C9orf72
  association: Hexanucleotide repeat expansion causes autosomal dominant FTD, often with ALS
  notes: Hexanucleotide (GGGGCC) repeat expansion on chromosome 9p21. Most common genetic cause of FTD. Causes FTLD-TDP pathology. Unique features include co-occurrence with ALS, psychotic symptoms, and paradoxically preserved social warmth. On digital cognitive assessment, C9orf72 carriers show the earliest and broadest deficits of the three genetic groups, spanning all six cognitive domains.
  evidence:
  - reference: PMID:26473392
    reference_title: "Distinct clinical and pathological phenotypes in frontotemporal dementia associated with MAPT, PGRN and C9orf72 mutations."
    supports: SUPPORT
    snippet: C9orf72 patients alone showed a co-occurrence of ALS. They showed more psychotic symptoms and irrational behaviour, yet were more often reported clinically as socially appropriate and warm.
    explanation: This highlights the distinctive clinical features of C9orf72-related FTD including the frequent association with ALS and unique behavioral profile.
  - reference: PMID:30711676
    reference_title: "Clinical and biomarker changes in presymptomatic genetic frontotemporal dementia."
    supports: SUPPORT
    snippet: Presymptomatic carriers of GRN and C9orf72 mutations, the most frequent genetic causes of frontotemporal lobar degeneration, represent the optimal target population for the development of disease-modifying drugs.
    explanation: This confirms C9orf72 as one of the most common genetic causes of FTD.
  - reference: PPR:PPR1289994
    reference_title: "The Ignite app detects early cognitive impairment and tracks disease severity in genetic frontotemporal dementia"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "mutation carriers showed the earliest and broadest deficits across all cognitive domains"
    explanation: Digital cognitive assessment of 569 Genetic FTD Initiative participants shows C9orf72 carriers have the earliest and broadest cognitive impairment of the three genetic groups.
- name: CHMP2B
  gene_term:
    preferred_term: CHMP2B (charged multivesicular body protein 2B, ESCRT-III subunit)
    term:
      id: hgnc:24537
      label: CHMP2B
  association: Heterozygous C-truncating variants cause autosomal dominant FTD-3
  notes: >-
    The gene behind the chromosome 3-linked pedigree. Its pathology is FTLD-UPS
    rather than FTLD-tau or FTLD-TDP, and the two alleles shown to produce the
    aberrant endosomal phenotype both truncate the CHMP2B C-terminus.
  evidence:
  - reference: PMID:16041373
    reference_title: "Mutations in the endosomal ESCRTIII-complex subunit CHMP2B in frontotemporal dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here we identify a mutation in CHMP2B, encoding a component of the
      endosomal ESCRTIII complex, and show that it results in aberrant mRNA
      splicing in tissue samples from affected members of this family.
    explanation: >-
      Establishes the gene-disease assertion for CHMP2B in the chromosome
      3-linked FTD family, and the splicing consequence of the founding allele.
  - reference: PMID:20301378
    reference_title: "CHMP2B-Related Frontotemporal Dementia-Amyotrophic Lateral Sclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      CHMP2B-FTD-ALS is inherited in an autosomal dominant manner. Penetrance is
      age dependent and appears to be nearly complete.
    explanation: >-
      GeneReviews gives the inheritance and penetrance for the CHMP2B form,
      which is what this genetic record asserts.
diagnosis:
- name: Montreal Cognitive Assessment
  description: >-
    Brief cognitive screening instrument. A validation study in
    behavioral-variant frontotemporal dementia found it more accurate than the
    MMSE for that syndrome, and in genetic frontotemporal dementia cohorts it
    distinguished presymptomatic pathogenic variant carriers from controls where
    the MMSE did not.
  notes: >-
    Copyright © Tina Brosseau for Center for Diagnosis & Research on Alzheimer's disease (CEDRA). Used with permission.
    The instrument is bound at its LOINC panel code and the cut-off at its
    total-score code. The instrument's items are not reproduced in this entry;
    only published thresholds are recorded. The genetic frontotemporal dementia
    study (PMID:39951678) reports group medians and discriminative accuracy but
    no cut-off, so it carries no range.
  measurements:
  - preferred_term: MoCA
    term:
      id: LOINC:72133-2
      label: Montreal Cognitive Assessment [MoCA]
  reference_ranges:
  - loinc_term:
      id: LOINC:72172-0
      label: Total score [MoCA]
    unit: '{score}'
    population: >-
      MoCA validation study for behavioral-variant frontotemporal dementia, three
      matched subgroups of 50 (bv-FTD, Alzheimer disease, healthy adults)
    notes: >-
      The abstract states the cut-off as "With a cutoff below 17 points"; a
      score below 17 falls in the positive band, which the half-open bands
      reproduce exactly. The cut-off was derived in the behavioral variant only.
    evidence:
    - reference: PMID:22859702
      reference_title: "Montreal Cognitive Assessment (MoCA): validation study for frontotemporal dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      snippet: "With a cutoff below 17 points, the MoCA results for sensitivity, specificity, positive predictive value, negative predictive value, and classification accuracy were significantly superior to those of the MMSE."
      explanation: States the MoCA cut-off for behavioral-variant frontotemporal dementia.
    interpretation_bands:
    - name: Below 17 (screen positive for bv-FTD)
      upper_bound: 17
      unit: '{score}'
      abnormal_flag: LOW
    - name: 17 or above
      lower_bound: 17
      unit: '{score}'
      abnormal_flag: NORMAL
  evidence:
  - reference: PMID:22859702
    reference_title: "Montreal Cognitive Assessment (MoCA): validation study for frontotemporal dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: "The MoCA is a sensitive and accurate instrument for screening the patients with bv-FTD and represents a better option than the MMSE."
    explanation: Supports the MoCA as a screening instrument for behavioral-variant frontotemporal dementia.
  - reference: PMID:39951678
    reference_title: "Montreal Cognitive Assessment vs the Mini-Mental State Examination as a Screening Tool for Patients With Genetic Frontotemporal Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: "MoCA demonstrated superior discriminative ability compared with MMSE (MoCA area under the curve [AUC] = 0.87, 95% CI 0.81-0.94; MMSE AUC = 0.80, 95% CI 0.72-0.89)."
    explanation: Supports the MoCA as the better screening instrument in genetic frontotemporal dementia.
- name: Mini-Mental State Examination
  description: >-
    Widely used cognitive screening instrument, recorded here because the
    frontotemporal dementia literature compares the MoCA against it and uses it
    to track severity. It is less sensitive in frontotemporal dementia than the
    MoCA, and in primary progressive aphasia its dependence on language
    overestimates dementia severity.
  notes: >-
    Copyright © Vicki King for Psychological Assessment Resources. Used with permission.
    No reference range is recorded: no cited source states a frontotemporal
    dementia cut-off or severity scheme for the MMSE. A PubMed search for
    mini-mental[ti] frontotemporal[ti] returned comparisons with the MoCA and
    studies of MMSE change over time, none stating a cut-off, and
    MMSE[ti] frontotemporal[ti] cut-off returned no records. The instrument's
    items are not reproduced in this entry.
  measurements:
  - preferred_term: MMSE
    term:
      id: LOINC:72107-6
      label: Mini-Mental State Examination [MMSE]
  evidence:
  - reference: PMID:39951678
    reference_title: "Montreal Cognitive Assessment vs the Mini-Mental State Examination as a Screening Tool for Patients With Genetic Frontotemporal Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: "MoCA distinguished between presymptomatic carriers and controls (median MoCA 28, 95% CI 27.0-29.0), but MMSE did not."
    explanation: Records the MMSE's insensitivity to the earliest stage of genetic frontotemporal dementia.
  - reference: PMID:18166606
    reference_title: "The mini-mental state examination in behavioral variant frontotemporal dementia and primary progressive aphasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: "Results suggest that the MMSE score, heavily dependent on language skill, overestimates dementia severity in PPA patients. However, the score may be a more accurate measure of functional impairment in bvFTD due to the influence of their executive function and attentional deficits on MMSE performance."
    explanation: Describes how MMSE severity readings differ between the behavioral and aphasic variants.
- name: Clinical Dementia Rating
  description: >-
    Global dementia staging instrument developed for Alzheimer's disease. In
    frontotemporal dementia it is used with two added domains for behaviour and
    language, as the CDR plus National Alzheimer's Coordinating Centre Behaviour
    and Language Domains (CDR plus NACC FTLD), whose global score grades disease
    stage in genetic frontotemporal dementia cohorts.
  notes: >-
    Copyright © Washington University Charles F. and Joanne Knight Alzheimer's Disease Research Center (Knight ADRC). Used with permission.
    The binding is the original CDR panel, the only CDR code LOINC carries. A
    search of the LOINC 2.83 table (the Tuva Project extract pinned in
    data/loinc/MANIFEST.yaml) for "CDR", "dementia rating", "FTLD" and
    "frontotemporal", and of the Monarch KG for "FTLD" and "frontotemporal
    dementia rating", found no code for the CDR plus NACC FTLD or its global or
    sum-of-boxes scores, so no stage bands are recorded. The instrument's items
    are not reproduced in this entry.
  measurements:
  - preferred_term: CDR
    term:
      id: LOINC:72088-8
      label: Clinical Dementia Rating scale [CDR]
  evidence:
  - reference: PMID:38152057
    reference_title: "Utility of the Japanese version of the Clinical Dementia Rating® plus National Alzheimer's Coordinating Centre Behaviour and Language Domains for sporadic cases of frontotemporal dementia in Japan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: "This study validated the Japanese version of the CDR® plus NACC FTLD with good reliability, validity, and responsiveness."
    explanation: The CDR extended with the NACC behaviour and language domains is a validated staging instrument in frontotemporal dementia.
  - reference: PMID:39951678
    reference_title: "Montreal Cognitive Assessment vs the Mini-Mental State Examination as a Screening Tool for Patients With Genetic Frontotemporal Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Grouping was based on the global CDR-plus-NACC-FTLD score."
    explanation: The global CDR plus NACC FTLD score is used to stage genetic frontotemporal dementia carriers.
treatments:
- name: Symptomatic Management
  description: No disease-modifying treatments currently available. Management focuses on behavioral symptoms with selective serotonin reuptake inhibitors for compulsive behaviors and agitation, and non-pharmacological approaches including behavioral interventions and caregiver support.
  treatment_term:
    preferred_term: Symptomatic Therapy
    term:
      id: NCIT:C170740
      label: Symptomatic Therapy
- name: Speech and Language Therapy
  description: Speech therapy interventions for patients with language-variant FTD to maintain communication abilities and quality of life for as long as possible.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
classifications:
  harrisons_chapter:
  - classification_value: NEUROLOGIC
  mechanistic_category:
  - classification_value: tauopathy
  - classification_value: proteotoxic disease
datasets:
- accession: geo:GSE13162
  title: Expression data from postmortem human brain samples with and without FTLD-U
  description: Microarray expression profiling of frontal cortex, hippocampus, and cerebellum from FTLD-U and control brains.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: MICROARRAY
  sample_types:
  - preferred_term: brain tissue
    tissue_term:
      preferred_term: brain
      term:
        id: UBERON:0000955
        label: brain
  sample_count: 56
  conditions:
  - frontotemporal lobar degeneration with ubiquitin-positive inclusions
  - control brain tissue
  notes: Includes 31 FTLD-U and 25 control samples.
references:
- reference: PMID:20301678
  title: "MAPT-Related Frontotemporal Dementia."
  tags:
  - GeneReviews
- reference: PMID:20301378
  title: "CHMP2B-Related Frontotemporal Dementia-Amyotrophic Lateral Sclerosis."
  tags:
  - GeneReviews
- reference: PMID:16041373
  title: "Mutations in the endosomal ESCRTIII-complex subunit CHMP2B in frontotemporal dementia."
- reference: PMID:17917582
  title: "A reassessment of the neuropathology of frontotemporal dementia linked to chromosome 3."
- reference: PMID:17956895
  title: "CHMP2B C-truncating mutations in frontotemporal lobar degeneration are associated with an aberrant endosomal phenotype in vitro."
- reference: DOI:10.1093/brain/awae074
  title: 'Synaptopathy: presynaptic convergence in frontotemporal dementia and amyotrophic lateral sclerosis'
  findings: []
- reference: DOI:10.1101/2024.02.09.579529
  title: Alterations in Lysosomal, Glial and Neurodegenerative Biomarkers in Patients with Sporadic and Genetic Forms of Frontotemporal Dementia
  findings: []
- reference: DOI:10.1186/s12974-024-03039-1
  title: Progranulin haploinsufficiency mediates cytoplasmic TDP-43 aggregation with lysosomal abnormalities in human microglia
  findings: []
- reference: DOI:10.1186/s40035-024-00429-6
  title: 'Tau in neurodegenerative diseases: molecular mechanisms, biomarkers, and therapeutic strategies'
  findings: []
- reference: DOI:10.21203/rs.3.rs-4103685/v1
  title: Large-scale network analysis of the cerebrospinal fluid proteome identifies molecular signatures of frontotemporal lobar degeneration
  findings: []
📚

References & Deep Research

References

10
PMID:20301678
MAPT-Related Frontotemporal Dementia.
No top-level findings curated for this source.
PMID:20301378
CHMP2B-Related Frontotemporal Dementia-Amyotrophic Lateral Sclerosis.
No top-level findings curated for this source.
PMID:16041373
Mutations in the endosomal ESCRTIII-complex subunit CHMP2B in frontotemporal dementia.
No top-level findings curated for this source.
PMID:17917582
A reassessment of the neuropathology of frontotemporal dementia linked to chromosome 3.
No top-level findings curated for this source.
PMID:17956895
CHMP2B C-truncating mutations in frontotemporal lobar degeneration are associated with an aberrant endosomal phenotype in vitro.
No top-level findings curated for this source.
DOI:10.1093/brain/awae074
Synaptopathy: presynaptic convergence in frontotemporal dementia and amyotrophic lateral sclerosis
No top-level findings curated for this source.
DOI:10.1101/2024.02.09.579529
Alterations in Lysosomal, Glial and Neurodegenerative Biomarkers in Patients with Sporadic and Genetic Forms of Frontotemporal Dementia
No top-level findings curated for this source.
DOI:10.1186/s12974-024-03039-1
Progranulin haploinsufficiency mediates cytoplasmic TDP-43 aggregation with lysosomal abnormalities in human microglia
No top-level findings curated for this source.
DOI:10.1186/s40035-024-00429-6
Tau in neurodegenerative diseases: molecular mechanisms, biomarkers, and therapeutic strategies
No top-level findings curated for this source.
DOI:10.21203/rs.3.rs-4103685/v1
Large-scale network analysis of the cerebrospinal fluid proteome identifies molecular signatures of frontotemporal lobar degeneration
No top-level findings curated for this source.

Deep Research

2

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Disorder ▸

Disorder

  • Name: Frontotemporal Dementia
  • Category: Complex
  • Existing deep-research providers: falcon
  • Existing evidence reference count in YAML: 16

Key Pathophysiology Nodes

  • TDP-43 Proteinopathy
  • Tau Proteinopathy
  • Frontal and Temporal Lobe Atrophy
  • Neuronal Death
  • Deep research literature mapping

Citation Inventory (for evidence mapping)

  • DOI:10.1093/brain/awae074
  • DOI:10.1101/2024.02.09.579529
  • DOI:10.1186/s12974-024-03039-1
  • DOI:10.1186/s40035-024-00429-6
  • DOI:10.15496/publikation-94419
  • DOI:10.21203/rs.3.rs-4103685/v1
Falcon ▸
Pathophysiology description
Edison Scientific Literature 23 citations 2026-02-01T12:53:11.362853

Pathophysiology description Frontotemporal dementia (FTD) encompasses frontotemporal lobar degeneration (FTLD) driven by distinct proteinopathies and convergent cellular stress pathways. The principal pathological classes are FTLD–TDP (abnormal TDP-43), FTLD–tau (abnormal MAPT/tau), and less commonly FTLD–FUS (abnormal FUS/FET proteins). Across genetic and sporadic forms, early synaptic failure—particularly at the presynapse—emerges as a convergent mechanism, followed by progressive neuronal loss and network disintegration in frontal and temporal cortices (paralimbic fronto–insular–striatal circuits) (overview; proportions and convergence on presynaptic dysfunction) (https://doi.org/10.1093/brain/awae074, Mar 2024) (clayton2024synaptopathypresynapticconvergence pages 1-2). Molecularly, risk genes and causal mutations perturb proteostasis (aggregation, phase transitions), RNA metabolism (splicing/transport), autophagy–lysosomal homeostasis, nucleocytoplasmic transport, and innate immune signaling. These processes interact: genetic and proteostatic stressors (e.g., C9orf72 repeat expansions, GRN haploinsufficiency, TMEM106B variation) drive TDP-43 dysfunction and synaptic failure; MAPT mutations drive tau misfolding with axonal and synaptic compromise; and glial activation amplifies neurodegeneration (https://doi.org/10.1186/s40035-024-00429-6 is a tau-focused background review; mechanistic points here from cited sources below) (huber2024mechanismsofneurodegeneration pages 57-60, saloner2025largescalenetworkanalysis pages 1-7, hsiaonakamoto2024alterationsinlysosomal pages 1-5, huber2024mechanismsofneurodegenerationa pages 79-82).

Recent systems–level CSF proteomics across autosomal-dominant FTLD (C9orf72, GRN, MAPT) shows increased RNA-splicing modules (notably in C9orf72, GRN), increased extracellular matrix modules (MAPT), and decreased synaptic/neuronal and autophagy modules, aligning in vivo fluid signatures with core mechanisms and suggesting hub proteins as potential biomarkers/targets (https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (saloner2025largescalenetworkanalysis pages 1-7).

1) Core Pathophysiology - Primary mechanisms - Proteinopathies: FTLD–TDP (~about half of cases), FTLD–tau (large fraction), FTLD–FUS (~minority) (synaptopathy review; mechanistic overview) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - Synaptic dysfunction: Early, convergent presynaptic deficits in vesicle priming, recycling, and local translation; TDP-43 loss-of-function reduces UNC13A and impairs priming, linking RNA-binding protein pathology to synaptic failure (https://doi.org/10.1093/brain/awae074, 2024; mechanistic synthesis) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60). - Autophagy–lysosome dysfunction: GRN haploinsufficiency and TMEM106B risk alleles disrupt autophagosome–lysosome maturation, acidification and cargo clearance; in FTLD, autophagy modules are reduced in CSF network analyses (https://doi.org/10.1186/s12974-024-03039-1, Feb 2024; https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (sung2024progranulinhaploinsufficiencymediates pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60, saloner2025largescalenetworkanalysis pages 1-7). - Nucleocytoplasmic transport impairment: Particularly in C9orf72 repeat expansion disease (loss-of-function and toxic gain-of-function via RNA foci and dipeptide repeat proteins) with downstream TDP-43 dyshomeostasis (https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (saloner2025largescalenetworkanalysis pages 1-7). - Neuroinflammation: Microglial and astrocytic activation; in GRN-related FTD, microglia show TDP-43 cytoplasmic aggregation with lysosomal abnormalities and complement C1q activation; glial biomarkers are elevated in biofluids (https://doi.org/10.1186/s12974-024-03039-1, Feb 2024; biofluid/tissue biomarker study) (sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33).

  • Dysregulated pathways
  • RNA splicing/processing, synaptic transmission, autophagy/lysosome, extracellular matrix remodeling; decreased synaptic and autophagy modules with increased RNA-splicing signatures in FTLD CSF proteomes (https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (saloner2025largescalenetworkanalysis pages 1-7).

  • TMEM106B–lysosome axis modulates TDP-43 dysfunction and C9orf72 DPR burden; UNC13A–synapse axis mediates TDP-43 loss-of-function at the presynapse (mechanistic consolidation) (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60, huber2024mechanismsofneurodegenerationa pages 57-60).

  • Cellular processes affected

  • Presynaptic vesicle priming/recycling, local translation, long-range axonal transport; autophagosome–lysosome fusion and acidification; nucleocytoplasmic shuttling; complement-mediated synapse/glia crosstalk (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60, sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5).

2) Key Molecular Players - Genes/Proteins (HGNC symbols) - GRN (progranulin): Haploinsufficiency causes lysosomal dysfunction and microglial activation; human microglia from GRN-FTD show cytoplasmic TDP-43 aggregation, lipid droplet accumulation, and profound lysosomal abnormalities with complement C1q activation (https://doi.org/10.1186/s12974-024-03039-1, Feb 2024) (sung2024progranulinhaploinsufficiencymediates pages 1-2). - C9orf72: Hexanucleotide repeat expansions cause combined loss-of-function and gain-of-function (RNA foci, dipeptide-repeat proteins) that impair RNA metabolism, nucleocytoplasmic transport, proteostasis and lead to TDP-43 aggregation (https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (saloner2025largescalenetworkanalysis pages 1-7). - MAPT (tau): Mutations drive tau aggregation, extracellular matrix and synaptic signaling alterations (CSF proteomics) and axonal/synaptic compromise in FTLD–tau (https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (saloner2025largescalenetworkanalysis pages 1-7). - TARDBP (TDP-43): Aggregation and nuclear loss-of-function disrupt RNA splicing/transport; presynaptic effects via UNC13A dysregulation (review evidence) (huber2024mechanismsofneurodegeneration pages 57-60, clayton2024synaptopathypresynapticconvergence pages 1-2). - FUS: Defines a minority FTLD–FUS class (overview) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - TMEM106B: Genetic modifier in FTLD–TDP; risk alleles/filament accumulation associate with endolysosomal defects, impaired RNA transport/local translation, and heightened TDP-43 dysfunction; knockdown increases DPR accumulation and disrupts autophagosome–lysosome maturation (mechanistic synthesis) (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60, huber2024mechanismsofneurodegenerationa pages 57-60). - UNC13A: Presynaptic vesicle priming factor; TDP-43–dependent cryptic exon inclusion and poly-PR decrease UNC13A, linking TDP-43 pathology to synaptic failure (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60).

  • Chemical entities (CHEBI terms; selected)
  • Glucosylsphingosine (GlcSph), ganglioside GM2, globoside GB3: Lysosomal lipid biomarkers increased in brain regions affected by GRN and sporadic FTD; plasma GlcSph elevated in asymptomatic GRN carriers (https://doi.org/10.1101/2024.02.09.579529, Feb 2024) (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33).
  • Neurofilament light (NfL): Axonal injury biomarker elevated across genetic and sporadic FTD; correlates with clinical severity and progression (https://doi.org/10.1101/2024.02.09.579529, Feb 2024) (hsiaonakamoto2024alterationsinlysosomal pages 1-5, huber2024mechanismsofneurodegenerationa pages 79-82).
  • GFAP (astroglial), YKL-40 (CHI3L1): Glial biomarkers elevated in asymptomatic GRN carriers and symptomatic FTD groups (pattern varies by genotype); tissue YKL-40 increased in affected regions (https://doi.org/10.1101/2024.02.09.579529, 2024) (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33).

  • Synaptic proteins NPTX2, NPTXR (neuronal pentraxins), VGF: Reduced in CSF across FTD, most pronounced in MAPT carriers; some correlate with disease severity (https://doi.org/10.1101/2024.02.09.579529, 2024) (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33).

  • Cell Types (CL terms; selected)

  • Neurons (principal cortical pyramidal neurons): primary degenerating cells with early synaptic failure (clayton2024synaptopathypresynapticconvergence pages 1-2).
  • Microglia: show disease-associated activation; in GRN deficiency, cell-intrinsic TDP-43 aggregation and lysosomal defects with complement activation; glial biomarkers elevated (sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5).
  • Astrocytes: reactive in FTLD; GFAP elevated in plasma/CSF; contribute to neuroinflammation and synaptic environment (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33).

  • Oligodendrocytes: can harbor inclusions in FTLD–TDP subtypes (overview) (huber2024mechanismsofneurodegeneration pages 57-60).

  • Anatomical locations (UBERON terms; selected)

  • Frontal and temporal cortices with prominent involvement of paralimbic fronto–insular–striatal (salience-related) networks; selective vulnerability of anterior temporal and insular regions underlies bvFTD and language variants (https://doi.org/10.15496/publikation-94419, May 2024) (reinermann2024thefunctionalconnectivity pages 14-17).

3) Biological Processes (for GO annotation; selected disrupted processes) - Protein aggregation, phase separation and inclusion formation (TDP-43, tau, FUS) (huber2024mechanismsofneurodegeneration pages 57-60, clayton2024synaptopathypresynapticconvergence pages 1-2). - RNA splicing/processing and RNA transport (TDP-43 loss-of-function; global RNA splicing module increases in CSF proteomics) (saloner2025largescalenetworkanalysis pages 1-7, huber2024mechanismsofneurodegeneration pages 57-60). - Nucleocytoplasmic transport (impaired in C9orf72 expansion disease) (saloner2025largescalenetworkanalysis pages 1-7). - Autophagy and lysosome organization/acidification; cargo trafficking (GRN/TMEM106B axis) (sung2024progranulinhaploinsufficiencymediates pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - Synaptic vesicle priming/exocytosis and presynaptic homeostasis (UNC13A, vesicle cycle) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - Complement activation and innate immune signaling in glia (C1q, YKL-40 elevation; microglial activation) (sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33). - Extracellular matrix remodeling (MAPT-associated CSF modules) (saloner2025largescalenetworkanalysis pages 1-7).

4) Cellular Components (selected) - Presynapse/synaptic vesicle pool; active zone (UNC13A-dependent priming) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - Lysosomes, late endosomes, autophagosomes and autolysosomes (GRN/TMEM106B-dependent maturation and acidification) (sung2024progranulinhaploinsufficiencymediates pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - Stress granules and ribonucleoprotein assemblies (RNA-binding proteinopathies; overview) (huber2024mechanismsofneurodegeneration pages 57-60). - Nucleus and cytoplasm (TDP-43 nucleocytoplasmic mislocalization) (huber2024mechanismsofneurodegeneration pages 57-60, saloner2025largescalenetworkanalysis pages 1-7).

5) Disease Progression - Sequence of events (typical mechanistic cascade): genetic risk/trigger (e.g., C9orf72 expansion; GRN loss; MAPT mutation; TMEM106B risk) → proteinopathy (TDP-43/tau/FUS misfolding and mislocalization) → early presynaptic dysfunction (vesicle priming/turnover; local translation) → impaired autophagy–lysosome clearance and nucleocytoplasmic transport → reactive glial responses and complement signaling → progressive neuronal/synaptic loss and network disintegration in frontal/temporal systems, manifesting as bvFTD or PPA variants (synthesis from reviews and biomarker/proteomics data) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60, saloner2025largescalenetworkanalysis pages 1-7, hsiaonakamoto2024alterationsinlysosomal pages 1-5). - Subtypes/stages: FTLD–TDP subtyping (A–D) and mixed pathologies occur; autosomal-dominant FTLD shows genotype-associated CSF module shifts (e.g., RNA splicing↑ in GRN/C9; ECM↑ in MAPT) and synaptic/autophagy module↓; these shifts mirror progression toward synaptic failure and lysosomal compromise (https://doi.org/10.21203/rs.3.rs-4103685/v1, 2025) (saloner2025largescalenetworkanalysis pages 1-7, hsiaonakamoto2024alterationsinlysosomal pages 1-5).

6) Phenotypic Manifestations - Core clinical phenotypes: behavioral variant FTD (bvFTD: disinhibition, apathy, loss of empathy, compulsions), and primary progressive aphasia variants (semantic and non-fluent/agrammatic), reflecting selective degeneration of salience/semantic networks in frontal/anterior temporal systems (network-level account) (https://doi.org/10.15496/publikation-94419, 2024) (reinermann2024thefunctionalconnectivity pages 14-17). - Clinicopathological links and mechanisms: presynaptic synaptopathy correlates with early cognitive/behavioral dysfunction; TDP-43 loss-of-function impacts synaptic genes (UNC13A), while GRN and TMEM106B lysosome biology contributes to neuroinflammation and clearance failure; in MAPT, synaptic/ECM alterations are prominent (synthesis) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60, saloner2025largescalenetworkanalysis pages 1-7, hsiaonakamoto2024alterationsinlysosomal pages 1-5).

Gene/protein annotations with ontology terms (examples) - GRN (HGNC:4601): lysosomal protein; processes: lysosome organization, regulation of inflammatory response, autophagy; components: lysosome, late endosome; evidence: human microglia TDP-43 aggregation with lysosomal abnormalities, complement activation in GRN haploinsufficiency (https://doi.org/10.1186/s12974-024-03039-1, 2024) (sung2024progranulinhaploinsufficiencymediates pages 1-2). - C9orf72 (HGNC:28339): GTPase regulator/trafficking; processes: nucleocytoplasmic transport, RNA metabolism, proteostasis; components: nucleus, cytoplasm, nuclear pore; evidence: combined loss- and gain-of-function with TDP-43 aggregation (https://doi.org/10.21203/rs.3.rs-4103685/v1, 2025) (saloner2025largescalenetworkanalysis pages 1-7). - MAPT (HGNC:6893): microtubule-associated protein; processes: microtubule stabilization, synaptic signaling; components: axon, somatodendritic compartments; evidence: ECM↑ and synaptic signaling alterations in MAPT FTLD CSF networks (https://doi.org/10.21203/rs.3.rs-4103685/v1, 2025) (saloner2025largescalenetworkanalysis pages 1-7). - TARDBP/TDP-43 (HGNC:11577): RNA-binding protein; processes: RNA splicing/transport; components: nucleus, cytoplasm; evidence: presynaptic synaptopathy via UNC13A dysregulation (review) (huber2024mechanismsofneurodegeneration pages 57-60, clayton2024synaptopathypresynapticconvergence pages 1-2). - FUS (HGNC:4010): RNA-binding; processes: RNA metabolism, stress granules; components: nucleus, stress granules; evidence: minority FTLD–FUS class (overview) (huber2024mechanismsofneurodegeneration pages 57-60, clayton2024synaptopathypresynapticconvergence pages 1-2). - TMEM106B (HGNC:24797): lysosomal membrane protein; processes: autophagosome–lysosome fusion, lysosomal acidification; components: lysosome, endolysosomal system; evidence: genetic modifier; DPR clearance; endolysosomal disruption (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60). - UNC13A (HGNC:12535): presynaptic priming; processes: synaptic vesicle exocytosis; components: active zone; evidence: TDP-43–dependent vulnerability and synaptic dysfunction (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60).

Phenotype associations (examples; HP terms) - Behavioral disinhibition, apathy, loss of empathy, compulsive behaviors, executive dysfunction; expressive language deficits (semantic variant, non-fluent variant) (network/clinical synthesis) (reinermann2024thefunctionalconnectivity pages 14-17).

Cell type involvement (examples; CL terms) - Neuron (principal excitatory neuron), microglial cell, astrocyte, oligodendrocyte; endothelial/vascular involvement is under active study but not established by the evidence set cited here (clayton2024synaptopathypresynapticconvergence pages 1-2, sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5).

Anatomical locations (UBERON terms) - Frontal lobe, temporal lobe, insula, anterior temporal pole; paralimbic fronto–insular–striatal network elements (reinermann2024thefunctionalconnectivity pages 14-17).

Chemical entities (CHEBI terms) - Glucosylsphingosine (GlcSph), ganglioside GM2, globoside GB3; NfL (protein biomarker), GFAP, YKL-40; neuronal pentraxins (NPTX2/NPTXR); VGF (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33, huber2024mechanismsofneurodegenerationa pages 79-82).

Evidence items and key statistics - Pathological classes and convergence: Most FTD belongs to FTLD–TDP or FTLD–tau; FTLD–FUS is less common. Early presynaptic dysfunction is a convergent, likely initiating mechanism across genetic backgrounds (https://doi.org/10.1093/brain/awae074, 2024) (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60). - TMEM106B modifies FTLD–TDP: risk alleles/filaments link to TDP-43 dysfunction and endolysosomal impairment; knockdown increases C9 DPRs and blocks autophagosome–lysosome maturation (mechanistic evidence compiled) (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60, huber2024mechanismsofneurodegenerationa pages 57-60). - GRN haploinsufficiency: human microglia from GRN-FTD show cytoplasmic TDP-43 aggregation, lysosomal abnormalities, complement C1q activation, and impaired phagocytosis (https://doi.org/10.1186/s12974-024-03039-1, Feb 2024) (sung2024progranulinhaploinsufficiencymediates pages 1-2). - CSF proteomics in genetic FTLD (n≈116 carriers vs 39 controls): RNA-splicing modules↑ (C9orf72, GRN), ECM modules↑ (MAPT), synaptic/neuronal and autophagy modules↓; signatures generalize to independent cohorts (https://doi.org/10.21203/rs.3.rs-4103685/v1, Mar 2025) (saloner2025largescalenetworkanalysis pages 1-7). - Biofluid/tissue biomarkers across FTD: plasma/CSF NfL↑ across forms (severity correlation); plasma GFAP↑ and CSF YKL-40↑ (notably in GRN and MAPT); CSF NPTX2/NPTXR↓ and VGF↓ (synaptic loss), strongest in MAPT; lysosomal lipids (GlcSph, GM2, GB3)↑ in disease-affected cortex; some markers (e.g., NPTXR) correlate with CDR+NACC FTLD severity (https://doi.org/10.1101/2024.02.09.579529, Feb 2024) (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33, hsiaonakamoto2024alterationsinlysosomal pages 33-38).

Applications and real‑world implementations - Biomarker applications: NfL (plasma/CSF) as a prognostic and pharmacodynamic marker across FTLD; plasma GFAP and CSF YKL‑40 for glial activation; CSF neuronal pentraxins (NPTX2/NPTXR) for synaptic integrity; genotype‑specific lysosomal lipids (e.g., plasma GlcSph in GRN) for stratification and presymptomatic monitoring; AD biomarkers (Aβ42/40, p‑tau) to exclude AD copathology in differential diagnosis (https://doi.org/10.1101/2024.02.09.579529, 2024; biomarker review perspective) (hsiaonakamoto2024alterationsinlysosomal pages 1-5, huber2024mechanismsofneurodegenerationa pages 79-82). - Therapeutic directions informed by mechanisms: Targeting lysosomal biology (GRN replacement/augmentation; TMEM106B modulation), nucleocytoplasmic transport (C9orf72 pathways), and synaptic resilience (UNC13A/synaptic vesicle cycle) are rational avenues suggested by convergent mechanisms and CSF network signatures (https://doi.org/10.21203/rs.3.rs-4103685/v1, 2025; mechanistic syntheses) (saloner2025largescalenetworkanalysis pages 1-7, huber2024mechanismsofneurodegeneration pages 57-60, clayton2024synaptopathypresynapticconvergence pages 1-2).

Expert opinions and analysis from authoritative sources - A 2024 Brain review synthesizes convergent presynaptic synaptopathy across ALS–FTD, arguing it is an early and targetable hub across genetic backgrounds (https://doi.org/10.1093/brain/awae074, Mar 2024) (clayton2024synaptopathypresynapticconvergence pages 1-2). - Mechanistic syntheses emphasize TMEM106B and UNC13A as central modulators linking lysosomal/autophagy and presynaptic machinery to TDP‑43 pathology, recommending pathway‑focused biomarker development (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60). - Systems proteomics in genetic FTLD recommends network‑based biomarker panels and highlights RNA splicing, ECM, synaptic, and autophagy modules as translational anchors (https://doi.org/10.21203/rs.3.rs-4103685/v1, 2025) (saloner2025largescalenetworkanalysis pages 1-7).

Ontology‑ready annotations (examples) - Genes/Proteins (HGNC): GRN; C9orf72; MAPT; TARDBP; FUS; TMEM106B; UNC13A (sung2024progranulinhaploinsufficiencymediates pages 1-2, saloner2025largescalenetworkanalysis pages 1-7, huber2024mechanismsofneurodegeneration pages 57-60). - GO Biological Process: protein aggregation; RNA splicing; nucleocytoplasmic transport; autophagy; lysosome organization; synaptic vesicle exocytosis; microglial activation; complement activation (saloner2025largescalenetworkanalysis pages 1-7, huber2024mechanismsofneurodegeneration pages 57-60, sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5). - GO Cellular Component: presynapse; synaptic vesicle; lysosome; autophagosome; nucleus; cytoplasm (clayton2024synaptopathypresynapticconvergence pages 1-2, huber2024mechanismsofneurodegeneration pages 57-60, sung2024progranulinhaploinsufficiencymediates pages 1-2). - Cell Types (CL): neuron; microglial cell; astrocyte; oligodendrocyte (clayton2024synaptopathypresynapticconvergence pages 1-2, sung2024progranulinhaploinsufficiencymediates pages 1-2, hsiaonakamoto2024alterationsinlysosomal pages 1-5, huber2024mechanismsofneurodegeneration pages 57-60). - Anatomical (UBERON): frontal lobe; temporal lobe; insula; anterior temporal pole (reinermann2024thefunctionalconnectivity pages 14-17). - Chemicals (CHEBI): glucosylsphingosine; ganglioside GM2; globoside GB3; neurofilament light; GFAP; YKL‑40; NPTX2; NPTXR; VGF (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33, huber2024mechanismsofneurodegenerationa pages 79-82).

Notes on prevalence/incidence - Epidemiology varies by study/region; mechanistic reviews emphasize FTD as a leading cause of young‑onset dementia with high heritability and frequent autosomal‑dominant forms (network/overview context) (huber2024mechanismsofneurodegenerationa pages 33-38, reinermann2024thefunctionalconnectivity pages 14-17). Because robust, region‑specific incidence statistics were not directly available in the evidence set cited here, summary rates are not included; readers should refer to contemporary epidemiologic consortia for region‑specific denominators.

Cited sources (URLs and publication dates embedded above; ID mapping for statements) - Presynaptic convergence in ALS–FTD: Brain (Mar 2024): https://doi.org/10.1093/brain/awae074 (clayton2024synaptopathypresynapticconvergence pages 1-2). - Mechanism-focused syntheses with TMEM106B/UNC13A, FTLD class overview: 2024 synaptic–mechanism review (huber2024mechanismsofneurodegeneration pages 57-60, huber2024mechanismsofneurodegenerationb pages 57-60, huber2024mechanismsofneurodegenerationa pages 57-60). - GRN microglia TDP-43 aggregation and lysosomal abnormalities: J Neuroinflammation (Feb 2024): https://doi.org/10.1186/s12974-024-03039-1 (sung2024progranulinhaploinsufficiencymediates pages 1-2). - Systems CSF proteomics in genetic FTLD: Research Square (Mar 2025): https://doi.org/10.21203/rs.3.rs-4103685/v1 (saloner2025largescalenetworkanalysis pages 1-7). - Biofluid/tissue biomarkers across sporadic and genetic FTD (lysosomal lipids, glial and synaptic markers): bioRxiv (Feb 2024): https://doi.org/10.1101/2024.02.09.579529 (hsiaonakamoto2024alterationsinlysosomal pages 1-5, hsiaonakamoto2024alterationsinlysosomal pages 30-33, hsiaonakamoto2024alterationsinlysosomal pages 33-38). - Network/anatomical locus emphasis: doctoral thesis (May 2024): https://doi.org/10.15496/publikation-94419 (reinermann2024thefunctionalconnectivity pages 14-17).

Direct quotes (selected) - “iMGs from FTD–GRN patients with PGRN deficiency exhibited… cytoplasmic TDP-43 aggregation and… lysosomal abnormalities… mediated by complement C1q activation” (J Neuroinflammation, Feb 2024) (sung2024progranulinhaploinsufficiencymediates pages 1-2). - “This evidence indicates that presynaptic synaptopathy is an early and convergent event in frontotemporal dementia and amyotrophic lateral sclerosis” (Brain, Mar 2024) (clayton2024synaptopathypresynapticconvergence pages 1-2).

Limitations and gaps - Pathology-specific in vivo biomarkers (e.g., direct assays for TDP-43 or DPRs) remain under development; NfL and glial/synaptic markers offer staging and monitoring but are not pathology-specific. Future work should integrate network proteomics, genotype‑specific lipidomics, and synaptic panels to enhance differential diagnosis and target engagement (huber2024mechanismsofneurodegenerationa pages 79-82, saloner2025largescalenetworkanalysis pages 1-7, hsiaonakamoto2024alterationsinlysosomal pages 1-5).

References

  1. (clayton2024synaptopathypresynapticconvergence pages 1-2): Emma L Clayton, Laura Huggon, Michael A Cousin, and Sarah Mizielinska. Synaptopathy: presynaptic convergence in frontotemporal dementia and amyotrophic lateral sclerosis. Brain, 147:2289-2307, Mar 2024. URL: https://doi.org/10.1093/brain/awae074, doi:10.1093/brain/awae074. This article has 19 citations and is from a highest quality peer-reviewed journal.

  2. (huber2024mechanismsofneurodegeneration pages 57-60): N Huber. Mechanisms of neurodegeneration in frontotemporal dementia: focus on synaptic dysfunction. Unknown journal, 2024.

  3. (saloner2025largescalenetworkanalysis pages 1-7): Rowan Saloner, Adam Staffaroni, Eric Dammer, Erik C.B. Johnson, Emily Paolillo, Amy Wise, Hilary Heuer, Leah Forsberg, Argentina Lario Lago, Julia Webb, Jacob Vogel, Alexander Santillo, Oskar Hansson, Joel Kramer, Bruce Miller, Jingyao Li, Joseph Loureiro, Rajeev Sivasankaran, Kathleen Worringer, Nicholas Seyfried, Jennifer Yokoyama, William Seeley, Salvatore Spina, Lea Grinberg, Lawren VandeVrede, Peter Ljubenkov, Ece Bayram, Andrea Bozoki, Danielle Brushaber, Ciaran Considine, Gregory Day, Bradford Dickerson, Kimiko Domoto-Reilly, Kelley Faber, Douglas Galasko, Daniel Geschwind, Nupur Ghoshal, Neill Graff-Radford, Chadwick Hales, Lawrence Honig, Ging-Yuek Hsiung, Edward Huey, John Kornak, Walter Kremers, Maria Lapid, Suzee Lee, Irene Litvan, Corey McMillan, Mario Mendez, Toji Miyagawa, Alexander Pantelyat, Belen Pascual, Henry Paulson, Leonard Petrucelli, Peter Pressman, Eliana Ramos, Katya Rascovsky, Erik Roberson, Rodolfo Savica, Allison Snyder, A. Campbell Sullivan, Carmela Tartaglia, Marijne Vandebergh, Bradley Boeve, Howie Rosen, Julio Rojas, Adam Boxer, and Kaitlin Casaletto. Large-scale network analysis of the cerebrospinal fluid proteome identifies molecular signatures of frontotemporal lobar degeneration. Research Square, Mar 2025. URL: https://doi.org/10.21203/rs.3.rs-4103685/v1, doi:10.21203/rs.3.rs-4103685/v1. This article has 19 citations.

  4. (hsiaonakamoto2024alterationsinlysosomal pages 1-5): Jennifer Hsiao-Nakamoto, Chi-Lu Chiu, Lawren VandeVrede, Ritesh Ravi, Brittany Vandenberg, Jack De Groot, Buyankhishig Tsogtbaatar, Meng Fang, Paul Auger, Neal S. Gould, Filippo Marchioni, Casey A. Powers, Sonnet S. Davis, Jung H. Suh, Jamal Alkabsh, Hilary W. Heuer, Argentina Lario Lago, Kimberly Scearce-Levie, William W. Seeley, Bradley F. Boeve, Howard J. Rosen, Amy Berger, Richard Tsai, Gilbert Di Paolo, Adam L. Boxer, Akhil Bhalla, and Fen Huang. Alterations in lysosomal, glial and neurodegenerative biomarkers in patients with sporadic and genetic forms of frontotemporal dementia. bioRxiv, Feb 2024. URL: https://doi.org/10.1101/2024.02.09.579529, doi:10.1101/2024.02.09.579529. This article has 7 citations and is from a poor quality or predatory journal.

  5. (huber2024mechanismsofneurodegenerationa pages 79-82): N Huber. Mechanisms of neurodegeneration in frontotemporal dementia: focus on synaptic dysfunction. Unknown journal, 2024.

  6. (huber2024mechanismsofneurodegenerationb pages 57-60): N Huber. Mechanisms of neurodegeneration in frontotemporal dementia: focus on synaptic dysfunction. Unknown journal, 2024.

  7. (sung2024progranulinhaploinsufficiencymediates pages 1-2): Wonjae Sung, Min-Young Noh, Minyeop Nahm, Yong Sung Kim, Chang-Seok Ki, Young-Eun Kim, Hee-Jin Kim, and Seung Hyun Kim. Progranulin haploinsufficiency mediates cytoplasmic tdp-43 aggregation with lysosomal abnormalities in human microglia. Journal of Neuroinflammation, Feb 2024. URL: https://doi.org/10.1186/s12974-024-03039-1, doi:10.1186/s12974-024-03039-1. This article has 20 citations and is from a peer-reviewed journal.

  8. (hsiaonakamoto2024alterationsinlysosomal pages 30-33): Jennifer Hsiao-Nakamoto, Chi-Lu Chiu, Lawren VandeVrede, Ritesh Ravi, Brittany Vandenberg, Jack De Groot, Buyankhishig Tsogtbaatar, Meng Fang, Paul Auger, Neal S. Gould, Filippo Marchioni, Casey A. Powers, Sonnet S. Davis, Jung H. Suh, Jamal Alkabsh, Hilary W. Heuer, Argentina Lario Lago, Kimberly Scearce-Levie, William W. Seeley, Bradley F. Boeve, Howard J. Rosen, Amy Berger, Richard Tsai, Gilbert Di Paolo, Adam L. Boxer, Akhil Bhalla, and Fen Huang. Alterations in lysosomal, glial and neurodegenerative biomarkers in patients with sporadic and genetic forms of frontotemporal dementia. bioRxiv, Feb 2024. URL: https://doi.org/10.1101/2024.02.09.579529, doi:10.1101/2024.02.09.579529. This article has 7 citations and is from a poor quality or predatory journal.

  9. (huber2024mechanismsofneurodegenerationa pages 57-60): N Huber. Mechanisms of neurodegeneration in frontotemporal dementia: focus on synaptic dysfunction. Unknown journal, 2024.

  10. (reinermann2024thefunctionalconnectivity pages 14-17): Leonie Isabelle Reinermann. The functional connectivity of cortical degenerations that are relevant to apraxia in patients with genetic ftd. Unknown, May 2024. URL: https://doi.org/10.15496/publikation-94419, doi:10.15496/publikation-94419. This article has 0 citations.

  11. (hsiaonakamoto2024alterationsinlysosomal pages 33-38): Jennifer Hsiao-Nakamoto, Chi-Lu Chiu, Lawren VandeVrede, Ritesh Ravi, Brittany Vandenberg, Jack De Groot, Buyankhishig Tsogtbaatar, Meng Fang, Paul Auger, Neal S. Gould, Filippo Marchioni, Casey A. Powers, Sonnet S. Davis, Jung H. Suh, Jamal Alkabsh, Hilary W. Heuer, Argentina Lario Lago, Kimberly Scearce-Levie, William W. Seeley, Bradley F. Boeve, Howard J. Rosen, Amy Berger, Richard Tsai, Gilbert Di Paolo, Adam L. Boxer, Akhil Bhalla, and Fen Huang. Alterations in lysosomal, glial and neurodegenerative biomarkers in patients with sporadic and genetic forms of frontotemporal dementia. bioRxiv, Feb 2024. URL: https://doi.org/10.1101/2024.02.09.579529, doi:10.1101/2024.02.09.579529. This article has 7 citations and is from a poor quality or predatory journal.

  12. (huber2024mechanismsofneurodegenerationa pages 33-38): N Huber. Mechanisms of neurodegeneration in frontotemporal dementia: focus on synaptic dysfunction. Unknown journal, 2024.