Steven Treon, MD, PhD, Dana-Farber Cancer Institute, Boston, MA, gives an overview of his talk at EMN 2021 on the interconnection between genotype and phenotype in Waldenström’s macroglobulinemia. MYD88 mutations occur in about 90-97% of patients with Waldenström’s macroglobulinemia and CXCR4 mutations occur in 30-40% of patients. Dr Treon shares an overview of how mutational status can impact disease presentation, diagnostics and prognostics, as well as how it can be used as a predictor for response to BTK inhibitors. This interview took place during the 2021 European Myeloma Network (EMN) congress.