Although PRMT5 inhibition has been shown to lead to a G1-arrest in solid cancers such as bladder urothelial cancer and glioblastoma (Banasavadi-Siddegowda et al., 2018; Tan et al., 2020), our data suggests that the mechanism of decreased cellular growth is more complex in MM: CCA profiles could not show G1-arrest in all HMCLS, as thus suggesting the presence of other pathways. Here, PRMT5 is linked to Miyoshi myopathy.