VCP and inclusion body myopathy with Paget disease of bone and frontotemporal dementia: This is further affirmed by the location of mutations in the p97 gene that cause the complex hereditary proteinopathy IBMPFD (inclusion body myopathy associated with Paget’s disease of the bone and frontotemporal dementia20, 21, 22) which is also being referred to as MSP1 (multisystem proteinopathy type 123).