Multisystem proteinopathy (MSP) is a dominantly inherited, pleiotropic, degenerative disorder of humans that can affect muscle, bone, and/or the central nervous system. MSP can manifest clinically as classical

amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...

(ALS), frontotemporal dementia (FTD), inclusion body myopathy (IBM), Paget's disease of bone (PDB), or as a combination of these disorders. Historically, several different names have been used to describe MSP, most commonly "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)." However, IBMPFD and IBMPFD/ALS are now considered outdated classifications and are more properly referred to as MSP, as the disease is clinically heterogeneous and its phenotypic spectrum extends beyond IBM, PDB, FTD, and ALS to include motor neuron disease, Parkinson's disease features, and ataxia features. Although MSP is rare, growing interest in this syndrome derives from the molecular insights the condition provides into the etiological relationship between common age-related degenerative diseases of muscle, bone, and brain.

Signs and symptoms

A useful operational definition of MSP is dominantly inherited degeneration that includes neurological involvement (either motor neuron disease or dementia) in combination with either distal myopathy or Pagetic bone degeneration. Most MSP patients present with weakness, and of these, approximately 65% present with motor neuron involvement. Although rare, MSP can also include involvement of cardiac, hepatic, visual, auditory, sensory, and autonomic systems. The histopathology of tissues affected by MSP includes ubiquitin-positive cytoplasmic inclusions of RNA-binding proteins, such as TDP-43,

HNRNPA1 Heterogeneous nuclear ribonucleoprotein A1 is a protein that in humans is encoded by the ''HNRNPA1'' gene. Mutations in hnRNP A1 are causative of amyotrophic lateral sclerosis and the syndrome multisystem proteinopathy. Function This gene ...

, HNRNPA2B1, and other components of RNA granules.

Genetics

MSP is a dominantly inherited and genetically heterogenous disease. The most common genetic cause of MSP is missense mutations affecting the valosin-containing protein (VCP) gene, which causes a subtype of MSP known as MSP1 (). Other pathogenic variants have been identified in HNRNPA2B1 and

, which cause MSP2 () and MSP3 () respectively. Additional genes linked to MSP include MATR3, OPTN, and p62/ SQSTM1.

Diagnosis

References

External links

{{Medical resources , ICD10 = , ICD9 = , ICDO = , OMIM = , DiseasesDB = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeSH = , GeneReviewsNBK = NBK1476 , GeneReviewsName = , Orphanet = 52430 Amyotrophic lateral sclerosis Rare diseases Genetic diseases and disorders