Gene expression profiles. (A) IgM-MM shows similar transcript expression of key MM proteins. (B) IgM-MM shows similar transcript expression of key t(11;14) MM proteins. (C) IgM-MM–specific transcript expression shows low levels of CD56 and CD117. (D) MYC gene set enrichment analysis and transcript levels showing upregulation in IgM-MM compared with non–IgM-MM. (E). Clustering of protein coding genes differentially expressed between non–IgM-MM and WM, showing preferential clustering of IgM-MM subtype with other MM samples and suggesting a unique transcriptional signature in this subgroup. (F) Volcano plot of differentially expressed genes between IgM-MM and non–IgM-MM with similarly differentially expressed genes between WM and non–IgM-MM labeled. (G) Heat map of B-cell–specific transcription factors expression profiles showing preferential clustering of IgM-MM subtype with other MM samples and separation in IgM-specific signature, and closer homology between WM and immature B cells. (H) Expression levels of clinically relevant genes. FC, fold change; NS, not significant.