Recurrent, heterozygous and mutually exclusive mutations of splicing factors SF3B1, SRSF2 and U2AF1 frequently occur in blood and solid cancers (for instance in myelodysplastic syndromes, chronic lymphocytic leukaemia, acute myeloid leukaemia, uveal melanoma and breast cancer).9 The gene discussed is SF3B1; the disease is B-cell chronic lymphocytic leukemia.