VCP and polyostotic fibrous dysplasia: A rare subtype is HIBM with Paget's disease of the bone and frontotemporal dementia (HIBM-PFD), which is due to the valosin-containing protein (VCP) gene mutations, resulting in abnormal accumulation of ubiquitinated proteins and impaired autophagy in IBM-PFD muscle (Watts et al., 2004; Ju et al., 2009; Nalbandian et al., 2011).