Richard Rosenquist, MD, PhD, Karolinska University Hospital, Solna, Sweden, discusses genetic testing in chronic lymphocytic leukemia (CLL). FISH (fluorescent in situ hybridization) analysis can detect 11q, 13q and 17p deletions and this way identify patients who are in high-risk groups and alter treatment accordingly. TP53 sequencing is also used. Both of these, 17p deletion and TP53 mutation, are predictive markers and identified patients need alternative treatment to standard chemoimmunotherapy. The workshop at ERIC 2020 will discuss how to interpret TP53 sequencing and other relevant gene mutations. This interview took place during the European Research Initiative on CLL (ERIC) International Virtual Meeting 2020.