DNMT3A and myelodysplastic syndrome: There were 627 (35%) CH-R and 373 (20%) CH-U cases, out of 1809 MDS patients (Fig. 5e); 97% of patients with CH-R had at least one dominant TET2 (55%), DNMT3A (24%), or ASXL1 (22%) mutation (Fig. 5f).