Type D refers to the pathology associated with InclusionBody Myopathy with Paget's Disease of Bone and Frontotemporal Dementia (IBMPFD)caused by valosin-containing protein (VCP) mutations and is characterized bynumerous short DN and frequent lentiform NII.58 Recently, some authors have suggested a new classificationbased on the molecular properties of TDP-43.59 The gene discussed is VCP; the disease is inclusion body myopathy with Paget disease of bone and frontotemporal dementia.