TET2 and myelodysplastic syndrome: In contrast, the presence of multi-hit mutations in TET2 was similar in CMML cases (with and without RS/SF3B1) and more frequent than in the MDS-RS/SF3B1 group, which explains the higher monocyte count that characterizes CMML, while cases with RS/SF3B1 (CMML or MDS) frequently showed co-mutations in DNMT3A, as previously described (29, 33).