U2AF1 and myelodysplastic syndrome: However, the mutation rate of 35 MDS and MDS/MPN patients was up to 77.1%, with high rates of ASXL1 (28.6%), U2AF1 (25.7%), RUNX1 (20%) and TET2 (17.1%), while the rate of cytogenetic abnormalities was only 41.4%, similar to previous reports.