In this study, we carried out the most comprehensive study of circRNAs in MM to date by performing deep total RNA sequencing (RNA‐seq) on two MM cohorts: a Danish cohort consisting of whole BM samples from 45 MM patients and 13 HCs, and a Norwegian cohort consisting of CD138‐purified plasma cells from 43 MM patients. Here, SDC1 is linked to Miyoshi myopathy.