Freda Stevenson, MSc, DPhil, FRCPath, FMedSci, University of Southampton, Southampton, UK, discusses how our understanding of chronic lymphocytic leukemia (CLL) has developed over the past 20 years. Research investigating immunoglobulin genes in human B-cell tumors did not start until the 1990s and required the knowledge of B-cell gene structure and somatic hypermutation. Importantly, the library of genes that are available today enabled a deeper understanding of B-cell genes in CLL, their origins and if they were somatically mutated. This interview took place during the European Research Initiative on CLL (ERIC) International Virtual Meeting 2020.