VCP and inclusion body myopathy with Paget disease of bone and frontotemporal dementia: Given these observations, the name of multisystem proteinopathy (MSP) has been proposed, using the nomenclature of MSP1 for IBMPFD caused by a VCP mutation, MSP2 for IBMPFD related to an HNRNPA2B1 mutation, MSP3 for IBMPFD related to an HNRNPA1 mutation, and MSP4 for IBMPFD due to some unidentified gene [22].