VCP-Associated Multisystem Proteinopathy
Introduction
Vcp Associated Multisystem Proteinopathy is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
VCP-associated multisystem proteinopathy (MSP), formerly known as inclusion body myopathy with Paget disease of bone and Frontotemporal Dementia (IBMPFD), is a rare autosomal dominant disorder caused by mutations in the VCP gene encoding valosin-containing protein (p97/VCP). This devastating condition is characterized by a variable combination of inclusion body myopathy, [ftd](/diseases/frontotemporal-dementia), Paget disease of bone, and [als](/diseases/amyotrophic-lateral-sclerosis), reflecting the essential role of VCP in protein homeostasis, [autophagy](/mechanisms/autophagy-lysosome-neurodegeneration)mechanisms/autophagy), and the [ubiquitin-proteasome-system](/mechanisms/ubiquitin-proteasome-system) . [@evangelista2022]
VCP is a AAA+ (ATPases Associated with diverse cellular Activities) ATPase that functions as a molecular segregase, using the energy of ATP hydrolysis to extract ubiquitinated proteins from membranes, chromatin, and protein complexes for downstream processing. It is one of the most abundant proteins in the cytoplasm, constituting approximately 1% of total cellular protein, and participates in more than 30 distinct cellular pathways. Mutations in VCP disrupt these pathways and lead to accumulation of ubiquitinated protein aggregates and [tdp-43](/proteins/tdp-43) pathology in affected tissues . [@palmio2023]
Genetics
VCP Gene and Protein Structure
The VCP gene is located on chromosome 9p13.3 and encodes a 806-amino acid protein consisting of: [@mozaffar2023]
- N-terminal domain (N-domain): Mediates interactions with cofactors and adaptors (e.g., p47, Ufd1-Npl4, UBXD1)
- D1 ATPase domain: First AAA+ domain; primarily involved in hexamer assembly
- D1-D2 linker: Connects the two ATPase domains
- D2 ATPase domain: Primary source of ATP hydrolysis and mechanical force generation
- C-terminal tail: Contains regulatory phosphorylation sites
VCP functions as a homohexameric ring, with substrate proteins threaded through the central pore during processing. The hexameric structure is critical for its segregase activity. [@altahan2022]
Disease-Causing Mutations
Over 50 pathogenic missense mutations have been identified in VCP, with the majority (~80%) clustering in the N-domain and D1-D2 linker region: [@fang2023]
- R155H: The most common mutation, accounting for ~50% of reported families
- R155C, R155P, R155S: Other substitutions at the R155 hotspot
- R191Q: Second most common mutation
- A232E: Located in the D1-D2 linker
- Rare mutations: In the D1 and D2 domains (e.g., N387H, A439S, D592N)
N-domain mutations are thought to alter cofactor binding and allosteric regulation of ATPase activity, leading to inappropriate or excessive substrate processing. Most mutations result in a gain of ATPase function with altered substrate selectivity . [@weihl2025]
Inheritance and Penetrance
VCP-MSP follows autosomal dominant inheritance with age-dependent penetrance:
- Myopathy: ~90% penetrance by age 50
- Paget disease of bone: ~50% penetrance by age 50
- FTD: ~30% penetrance by age 50
- ALS: ~10-15% penetrance
Penetrance varies significantly between families carrying the same mutation, suggesting the influence of genetic modifiers and environmental factors. Sex influences the clinical phenotype, with some studies reporting higher rates of ALS in males .
Clinical Manifestations
Inclusion Body Myopathy
The myopathy is typically the earliest and most common manifestation, presenting in the third to fifth decade of life:
- Pattern: Proximal and distal limb weakness, often asymmetric
- Onset: Progressive limb-girdle weakness, initially affecting the hip girdle and quadriceps
- Progression: Gradual spread to shoulder girdle and distal muscles; wheelchair dependence within 5-15 years of onset
- CK levels: Mildly to moderately elevated (2-10x normal)
- Muscle biopsy: Shows rimmed vacuoles, [tdp-43](/proteins/tdp-43)-positive inclusions, ubiquitin-positive aggregates, and p62-positive bodies
The myopathy differs from sporadic inclusion body myositis (IBM) in its earlier onset, autosomal dominant inheritance, absence of inflammatory infiltrates, and presence of [tdp-43](/proteins/tdp-43) pathology rather than amyloid deposits .
Frontotemporal Dementia
VCP mutations cause [ftd](/diseases/frontotemporal-dementia) with [tdp-43](/proteins/tdp-43) pathology] (FTLD-TDP type D), characterized by:
- Clinical presentation: Behavioral variant FTD (bvFTD) is the most common phenotype, with progressive personality changes, disinhibition, apathy, and executive dysfunction
- Age of onset: Typically 50s-60s, later than the myopathy
- Neuroimaging: Frontal and temporal lobe atrophy on [neuroimaging](/diagnostics/neuroimaging)
- Neuropathology: Ubiquitin and [tdp-43](/proteins/tdp-43)-positive neuronal intranuclear inclusions (type D pattern, unique to VCP mutations), neuronal cytoplasmic inclusions, and dystrophic neurites
The FTLD-TDP type D pattern — with abundant lentiform neuronal intranuclear inclusions — is highly distinctive and virtually pathognomonic for VCP mutations.
Paget Disease of Bone
Paget disease of bone involves focal areas of increased bone turnover, leading to:
- Skeletal deformity: Enlarged, thickened bones with disorganized lamellar architecture
- Commonly affected bones: Spine, pelvis, skull, and long bones
- Complications: Pain, pathologic fractures, hearing loss (petrous bone involvement), and rarely osteosarcoma
- Biochemistry: Elevated serum alkaline phosphatase; elevated urinary hydroxyproline/deoxypyridinoline
- Treatment: Bisphosphonates (zoledronic acid, pamidronate)
Amyotrophic Lateral Sclerosis
VCP mutations account for 1-2% of familial [als](/diseases/amyotrophic-lateral-sclerosis):
- Clinical features: Upper and lower motor neuron signs, progressive weakness, bulbar involvement
- Distinction: May coexist with myopathy, complicating differentiation of lower motor neuron ALS from myopathic weakness
- [tdp-43](/proteins/tdp-43) pathology: Present in motor [neurons](/entities/neurons), as in other forms of ALS
Other Associated Phenotypes
Additional features reported in VCP-MSP include:
- Cardiomyopathy: Dilated cardiomyopathy in some families
- Parkinsonism: Rarely reported; may reflect [basal-ganglia](/brain-regions/basal-ganglia) involvement
- Cataracts: Posterior subcapsular cataracts
- Hepatic steatosis: Fatty liver disease
- Sensory neuropathy: Peripheral nerve involvement
- Sphincter dysfunction: Urinary and bowel involvement in advanced disease
Pathophysiology
VCP Cellular Functions
VCP/p97 is a master regulator of protein quality control with roles in:
Endoplasmic reticulum-associated degradation (ERAD): Extracts misfolded proteins from the ER membrane for proteasomal degradation via the [ubiquitin-proteasome-system](/mechanisms/ubiquitin-proteasome-system)
[autophagy](/mechanisms/autophagy-lysosome-neurodegeneration)mechanisms/autophagy): Required for autophagosome maturation, autophagic flux, and [mitophagy](/mechanisms/mitophagy) (VCP/p97 is essential for [pink1](/proteins/pink1-protein)/[prkn](/genes/prkn)-mediated mitophagy)
Chromatin-associated degradation (CAD): Removes damaged proteins from chromatin during [dna-damage-repair](/mechanisms/dna-damage-repair)
Membrane fusion: Participates in Golgi and ER membrane reassembly after mitosis
[nf-kb](/entities/nf-kb) signaling: Processes the [nf-kb](/entities/nf-kb) precursor p100 to p52
Stress granule clearance: Removes and degrades stress granule components, including RNA-binding proteinsDisease Mechanisms
VCP mutations cause disease through several interconnected mechanisms :
[autophagy](/mechanisms/autophagy-lysosome-neurodegeneration)mechanisms/autophagy) Impairment: Mutant VCP leads to accumulation of immature autophagosomes that fail to fuse with lysosomes. Autophagosome-lysosome fusion defects result in accumulation of ubiquitinated protein aggregates, damaged mitochondria, and [p62-sqstm1](/proteins/p62-sqstm1)-positive inclusion bodies.
[tdp-43](/proteins/tdp-43) Mislocalization and Aggregation: VCP mutations cause cytoplasmic mislocalization of [tdp-43](/proteins/tdp-43) from its normal nuclear location. Cytoplasmic [tdp-43](/proteins/tdp-43) forms phosphorylated, ubiquitinated, and truncated aggregates — the hallmark pathological feature of VCP-MSP across all affected tissues (muscle, brain, spinal cord).
Impaired Stress Granule Dynamics: VCP normally disassembles stress granules after cellular stress resolves. Mutant VCP permits persistent stress granules, which may seed pathological protein aggregation, including [tdp-43](/proteins/tdp-43) and [fus](/entities/fus) aggregates. This connects VCP-MSP to the broader concept of [liquid-liquid-phase-separation](/mechanisms/liquid-liquid-phase-separation) dysfunction in neurodegeneration.
Mitochondrial Dysfunction: Defective [mitophagy](/mechanisms/mitophagy) leads to accumulation of damaged mitochondria, increased [oxidative-stress](/mechanisms/oxidative-stress), and impaired cellular energetics.
Proteasome Dysfunction: While the [ubiquitin-proteasome-system](/mechanisms/ubiquitin-proteasome-system) itself is not directly impaired, the inability of mutant VCP to extract substrates for proteasomal delivery results in functional proteasome insufficiency.
Tissue Selectivity
Why VCP mutations preferentially affect muscle, bone, and brain remains incompletely understood. Proposed explanations include:
- These tissues have high protein turnover demands and limited reserve capacity for proteostasis
- Post-mitotic cells (muscle fibers, [neurons](/entities/neurons) cannot dilute accumulated aggregates through cell division
- Tissue-specific VCP cofactors may be differentially affected by mutations
- [selective-neuronal-vulnerability](/mechanisms/selective-neuronal-vulnerability) factors may determine which brain regions are affected
Diagnosis
Diagnostic Criteria
A clinical diagnosis of VCP-MSP requires molecular confirmation. Clinical suspicion should be raised in patients with:
- Hereditary inclusion body myopathy with rimmed vacuoles
- Early-onset Paget disease of bone
- Familial FTD with [tdp-43](/proteins/tdp-43) pathology
- Familial ALS
- Any combination of myopathy, Paget disease, FTD, or ALS in a single individual or family
Diagnostic Workup
- Genetic testing: Sequencing of the VCP gene; may be identified through multigene panels for hereditary myopathy, FTD, or ALS
- Muscle biopsy: Rimmed vacuoles, [tdp-43](/proteins/tdp-43)+ inclusions, ubiquitin+ aggregates, p62+ bodies
- Skeletal imaging: Bone scan or plain radiographs showing Paget disease
- Serum alkaline phosphatase: Elevated in Paget disease
- EMG/nerve conduction studies: Myopathic changes; may show superimposed neuropathic features
- Brain MRI: Frontal and temporal atrophy if FTD is present
- CSF [csf-biomarkers](/diagnostics/csf-biomarkers): [neurofilament-light](/biomarkers/neurofilament-light-chain-nfl)) may be elevated
Differential Diagnosis
- Sporadic inclusion body myositis (IBM): Later onset, inflammatory infiltrates, anti-cN1A antibodies
- GNE myopathy (HIBM2): Autosomal recessive, spares quadriceps
- Other genetic FTD: [grn](/genes/grn), [c9orf72](/genes/c9orf72), [mapt](/genes/mapt) mutations
- Sporadic ALS: No family history, no myopathy or Paget disease
- Sporadic Paget disease: Common in elderly, no associated myopathy or dementia
Management and Treatment
Current Standard of Care
No disease-modifying therapy exists for VCP-MSP. Management is supportive and multidisciplinary :
Myopathy Management:
- Physical therapy and occupational therapy to maintain function
- Assistive devices (ankle-foot orthoses, wheelchair) as weakness progresses
- Monitoring for respiratory muscle weakness; non-invasive ventilation when indicated
- Avoidance of statin medications (may worsen myopathy)
- Cardiac monitoring (echocardiography) for cardiomyopathy screening
Paget Disease Management:
- Bisphosphonates (zoledronic acid: single IV infusion often provides prolonged remission)
- Pain management
- Orthopedic surgery for fractures or deformity
- Hearing assessment if skull is involved
FTD Management:
- Behavioral interventions and environmental modifications
- Selective serotonin reuptake inhibitors (SSRIs) for behavioral symptoms
- Caregiver education and support
- Advance care planning
ALS Management:
- [riluzole](/therapeutics/riluzole) (modest survival benefit)
- Respiratory support (non-invasive ventilation, cough assist)
- Multidisciplinary ALS clinic care
- Nutritional support (PEG tube when indicated)
Therapeutic Development
Several therapeutic strategies are under investigation :
- VCP-targeted small molecules: Compounds that correct mutant VCP function without inhibiting the wild-type protein
- [autophagy](/mechanisms/autophagy-lysosome-neurodegeneration)mechanisms/autophagy) modulators: Enhancing autophagic flux to clear protein aggregates (e.g., rapamycin, [mtor-neurodegeneration](/mechanisms/mtor-neurodegeneration) inhibitors, [tfeb](/proteins/tfeb) activators)
- Antisense oligonucleotides: [aso-therapy](/therapeutics/aso-therapy) targeting mutant VCP allele (allele-specific knockdown)
- [gene-therapy](/therapeutics/gene-therapy): AAV-mediated gene replacement or CRISPR-based correction
- [tdp-43](/proteins/tdp-43) aggregation inhibitors: Preventing downstream [tdp-43](/proteins/tdp-43) pathology
- Exercise therapy: Structured aerobic and resistance exercise programs adapted to disease stage
Clinical Trials
VCP-MSP is a rare disease, and clinical trials are limited. The Cure VCP Disease Foundation and international consortia are working to establish natural history studies, registries, and biomarker development programs to enable future therapeutic trials .
Epidemiology
VCP-MSP is rare, with an estimated prevalence of fewer than 1 in 100,000 individuals. Over 300 families have been reported worldwide. The disorder is likely underdiagnosed due to:
- Variable expressivity (some patients present with only one feature)
- Late onset of some manifestations
- Misdiagnosis as sporadic IBM, idiopathic FTD, or sporadic ALS
- Limited awareness among clinicians
VCP in Broader Neurodegenerative Disease Context
VCP mutations illuminate fundamental principles of [neurodegeneration]:
- Converging pathways: VCP-MSP demonstrates that defects in protein quality control ([autophagy](/mechanisms/autophagy-lysosome-neurodegeneration)mechanisms/autophagy), [UPS](/mechanisms/ubiquitin-proteasome-system), ERAD) converge on [tdp-43](/proteins/tdp-43) aggregation — the same pathological endpoint seen in sporadic ALS and ~50% of FTD cases
- [prion-like-spreading](/mechanisms/prion-like-spreading): [tdp-43](/proteins/tdp-43) pathology in VCP-MSP may spread via templated misfolding
- Multisystem vulnerability: The same genetic defect affects skeletal muscle, bone, brain, and motor [neurons](/entities/neurons), highlighting the tissue-specific consequences of proteostasis failure
- Therapeutic target: Understanding VCP function informs therapeutic strategies for the much larger population of patients with sporadic [tdp-43](/proteins/tdp-43) proteinopathies
External Links
- [OMIM: VCP (601023)(https://omim.org/entry/601023)
- [OMIM: IBMPFD (167320)(https://omim.org/entry/167320)
- [Cure VCP Disease Foundation](https://www.curevcp.org/)
- [GeneReviews: Multisystem Proteinopathy](https://www.ncbi.nlm.nih.gov/books/NBK1476/)
Background
The study of Vcp Associated Multisystem Proteinopathy has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
Recent Research (2024-2026)
Recent advances in VCP-Associated Multisystem Proteinopathy have focused on understanding disease mechanisms, identifying biomarkers, and developing novel therapeutic approaches. Key developments include:
- Genetic studies: Identification of new genetic risk factors and mechanistic insights
- Biomarker research: Development of diagnostic and prognostic biomarkers
- Therapeutic approaches: Investigation of novel treatment strategies
- Clinical trials: Ongoing Phase I-III trials for new therapies
Allen Brain Atlas Resources
- [Allen Brain Atlas - Gene Expression](https://human.brain-map.org/) - Search for gene expression data across brain regions
- [Allen Brain Atlas - Cell Types](https://celltypes.brain-map.org/) - Explore neuronal cell type taxonomy
- [Allen Brain Atlas - Aging, Dementia & TBI](https://aging.brain-map.org/) - Data on aging and traumatic brain injury
- [BrainSpan Atlas of the Developing Human Brain](https://brainspan.org/) - Developmental gene expression data
References
[Scarian E, et al., (2024). Valosin-Containing Protein (VCP): A Review of Its Diverse Molecular Functions and Clinical Phenotypes. International Journal of Molecular Sciences, 25(11):5633. [DOI: 10.3390/ijms25115633. [PubMed) (2024)](https://pubmed.ncbi.nlm.nih.gov/38891822/)
[Evangelista T, et al., (2022). Multisystem Proteinopathy Due to VCP Mutations: A Review of Clinical Heterogeneity and Genetic Diagnosis. Genes, 13(6):963. [DOI: 10.3390/genes13060963. [PubMed) (2022)](https://pubmed.ncbi.nlm.nih.gov/35741724/)
[Palmio J, et al., (2023). Sex influences clinical phenotype in valosin-containing protein mutations. Clinical Neurology and Neurosurgery, 231:107875. [DOI: 10.1016/j.clineuro.2023.107875. [PubMed) (2023)](https://pubmed.ncbi.nlm.nih.gov/37441929/)
[Mozaffar T, et al., (2023). Provisional practice recommendation for the management of myopathy in VCP-associated multisystem proteinopathy. Annals of Clinical and Translational Neurology, 10(5):739-753. [DOI: 10.1002/acn3.51760. [PubMed) (2023)](https://pubmed.ncbi.nlm.nih.gov/37026610/)
[Al-Tahan S, et al., (2022). Development of a standard of care for patients with VCP-associated multisystem proteinopathy. Orphanet Journal of Rare Diseases, 17:23. [DOI: 10.1186/s13023-022-02172-5. [PubMed) (2022)](https://pubmed.ncbi.nlm.nih.gov/35093159/)
[Fang X, et al., (2023). Therapeutic developments for valosin-containing protein mediated multisystem proteinopathy. Current Opinion in Neurology, 36(5):432-440. [DOI: 10.1097/WCO.0000000000001184. [PubMed) (2023)](https://pubmed.ncbi.nlm.nih.gov/37678339/)
[Weihl CC, et al., (2025). 2024 VCP International Conference: Exploring multi-disciplinary approaches from basic science of valosin containing protein to clinical management. Neurobiology of Disease, 205:106861. [DOI: 10.1016/j.nbd.2025.106861. [PubMed) (2025)](https://pubmed.ncbi.nlm.nih.gov/40037468/)