SF3B1 and B-cell chronic lymphocytic leukemia: In CLL, the frequency of SF3B1 mutations increases with disease evolution and treatment (Rossi et al, 2011; Baliakas et al, 2015; Leeksma et al, 2019), and a hotspot mutation region has been identified between the fifth and eighth Huntington elongation factor 3 PR65/A TOR (HEAT) domain repeats of the protein, encoded by exons 14–16, K700E being the most frequent mutation (Wan & Wu, 2013).