Multistep disease models of MM and WM. (Upper panel) The current clinical and genetic multistep model of the initiation and progression of MGUS to MM. (Lower panel) The newly proposed multistep model of WM where sequencing data have been mapped onto the clinical disease stages of IgM-MGUS, aWMst, aWMpr, and symptomatic WM. Increasing tumor mutational burden and CNA are characteristics of disease progression. SNV, single nucleotide variant.