Mutations in the SF3B1 gene cluster in the selected HEAT repeats of the SF3B1 protein, and have been identified in 4–12% of CLL patients, with a higher frequency at the time of disease progression13; SF3B1 mutations are correlated with a shorter duration of remission after treatment, fludarabine-refractory disease, and poorer OS35,36. This evidence concerns the gene SF3B1 and B-cell chronic lymphocytic leukemia.