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 (ALS), frontotemporal dementia (FTD), inclusion body myopathy (IBM), Paget's disease of bone (PDB), or as a combination of these disorders.
[1] 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)."
[3][4] 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.
[4] The histopathology of tissues affected by MSP includes ubiquitin-positive cytoplasmic inclusions of RNA-binding proteins, such as TDP-43, HNRNPA1, HNRNPA2B1, and other components of RNA granules.