Multisystem proteinopathy
Rare inherited degenerative disease affecting muscle, bone, and nervous system.
Multisystem proteinopathy (MSP) is a rare, inherited disorder that causes progressive damage to several organ systems at once, most often the muscles, bones, and nervous system. It appears in adulthood and can vary widely in its genetic origins. People with MSP typically develop one or more of these conditions: amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), inclusion body myopathy (IBM), or Paget's disease of bone (PDB). The condition is most frequently triggered by a missense mutation in the VCP gene, though at least four other genes are also known to cause it.
Historically, MSP went by names such as "inclusion body myopathy with early-onset Paget disease and frontotemporal dementia" (IBMPFD) or "inclusion body myopathy with frontotemporal dementia, Paget's disease of bone, and amyotrophic lateral sclerosis" (IBMPFD/ALS). These older labels are now considered outdated because MSP’s clinical picture is broader than just IBM, PDB, FTD, and ALS; it can also include motor neuron disease, features of Parkinson’s disease, and ataxia. Although rare, MSP has drawn growing scientific interest because it offers molecular clues to how common age-related degenerative diseases of muscle, bone, and brain are connected.
Signs and symptoms vary by organ system. In muscle, inclusion body myopathy is often the first sign, leading to progressive weakness that makes climbing stairs, walking, lifting arms, and using hands difficult. Patients may also experience muscle pain, cramps, and spasms. In the skeleton, about half of MSP patients develop Paget’s disease of bone, which results from excessive bone turnover and can cause pain, fractures, hearing loss, and deformities. Cognitively, roughly one-third of patients develop frontotemporal dementia, marked by behavioral changes, disinhibition, apathy, emotional dysregulation, and language problems. Alzheimer’s disease and mixed cognitive impairment have been reported in isolated cases. Respiratory issues are common and include shortness of breath, weak cough, aspiration, sleep-disordered breathing, infections, and respiratory failure. Motor neuron disease or ALS can also occur, with symptoms such as progressive weakness, tremors, fasciculations, swallowing difficulties, weight loss, and speech problems—many of which overlap with other MSP features. A few patients have developed Parkinsonism symptoms like tre
- type
- Disease
- inheritance
- Autosomal dominant
- most_common_gene
- VCP
- other_genes
- HNRNPA2B1, HNRNPA1, p62/SQSTM1, MATR3, OPTN
- typical_age_of_onset
- Adult
- primary_affected_systems
- Muscle, bone, nervous system
Quick Facts
- Specialty
- neurology
Facts from the source article.
Lore & Background
Historically, MSP was known as inclusion body myopathy with early-onset Paget disease and frontotemporal dementia (IBMPFD) or IBMPFD/ALS, but these classifications are now considered outdated. The disease is clinically heterogeneous, with a phenotypic spectrum extending beyond IBM, PDB, FTD, and ALS to include motor neuron disease, Parkinson's disease features, and ataxia. Growing interest in MSP derives from molecular insights it provides into the etiological relationship between common age-related degenerative diseases of muscle, bone, and brain.
Reader's Guide
Multisystem proteinopathy is significant because it links several common age-related degenerative diseases—ALS, FTD, IBM, and Paget's disease of bone—through a shared molecular mechanism involving abnormal protein clearance. The most common genetic cause is a missense mutation in the VCP gene, which leads to ubiquitin-positive cytoplasmic inclusions of RNA-binding proteins and other components of RNA granules. Diagnosis relies on genetic testing for VCP and other MSP genes, and management is symptomatic, with no cure or disease-modifying therapy available. The condition highlights the importance of protein homeostasis in neurodegeneration and musculoskeletal disease, and organizations such as Cure VCP Disease support research and advocacy. Its study offers insights into the pathogenesis of more common disorders and potential therapeutic targets.
Did You Know?
- The most common cause of MSP is a missense mutation affecting the valosin-containing protein (VCP) gene.
- Approximately one third of MSP patients are affected by frontotemporal dementia (FTD).
- Paget's disease of bone affects about half of MSP patients.
- There is no cure or disease modifying therapy for MSP.
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