Other examples include mutations in factors that function early in spliceosome formation, such as mutations in the U2 snRNP auxiliary factor (U2AF), SRSF2 and the U2 snRNP SF3b1 protein, which have been linked to myelodysplastic syndromes that often progress to chemotherapy-resistant secondary acute myeloid leukemia48. The gene discussed is SF3B1; the disease is myelodysplastic syndrome.