Valosin-containing protein (VCP) gene mutations have been associated with a rare autosomal dominant, adult-onset progressive disease known as multisystem proteinopathy 1 (MSP1), or inclusion body myopathy (IBM), Paget’s disease of bone (PDB), frontotemporal dementia (FTD), (IBMPFD), and amyotrophic lateral sclerosis (ALS). The gene discussed is VCP; the disease is bone Paget disease.