Expression patterns of 52 genes segregate MGUS and MGUS-L MM from non–MGUS-L MM. Two-dimensional unsupervised hierarchical cluster analysis of 52 MGUS genes (rows) in CD138-enriched plasma cells of patients with MGUS (n = 56), MM from MGUS (n = 16), and newly diagnosed MM (n = 351) (columns). The left branch consists of MGUS and MGUS-like MM samples (horizontal green bar), and the right branch contains the non–MGUS-L MM (horizontal red bar). Green arrows represent MGUS patients (MM-L MGUS).