The differential binding of UFD2a and UFD2a-7/7a to VCP/p97 is also of interest given that mutations in this AAA-type ATPase are present in patients with inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia and cause complete disease pathology in transgenic mice [60], [61]. This evidence concerns the gene UBE4B and bone Paget disease.