VCP and frontotemporal dementia: Multisystem proteinopathy 1 (MSP1) or inclusion body myopathy (IBM) associated with Paget's disease of the bone, frontotemporal dementia (FTD) (IBMPFD), and amyotrophic lateral sclerosis (ALS) is a rare syndromic disease caused by gain‐of‐function variants in the valosin‐containing protein (VCP) gene.1, 2