Mutations in the valosin-containing protein (VCP) gene were the first identified cause of IBMPFD,1,2 but reports of families without linkage to chromosome 9 established the genetic heterogeneity of the disorder.3,4 It has recently emerged that mutations in the HNRNPA2B1 (chromosome 7) and HNRNPA1 (chromosome 12) genes account for some families with IBMPFD.5
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3908355/