1. GeneSequenceTa °CFunction IDH1 exon 4 Fw5'-AGCTCTATATGCCATCACTGC-3' 62 Methylation Rv 5 ’ -AACATGCAAAATCACATTATTGCC-3 ’ IDH2 exon 4 Fw 5 ’ -AATTTTAGGACCCCCGTCTG-3 ’ 62 Rv 5 ’ -CTGCAGAGACAAGAGGATGG-3 ’ DNMT3A exon 23 Fw 5 ’ -TCCTGCTGTGTGGTTAGACG-3 ’ 62 Rv 5 ’ -ATGATGTCCAACCCTTTTCG-3 ’ U2AF1 exon 2 Fw 5 ’ -CATATTCCATGTGTTTGATA-3 ’ 50 Splicing Rv 5 ’ -TAGAAATTAACTGTCTTTGAA-3 ’ SF3B1 exons 13-14 Fw 5 ’ -ATAGTTGATATATTGAGAGAA-3 ’ 60 Rv 5 ’ -AGTTTACATTAACAAATCTG-3 ’ SF3B1 exons 15-16 Fw 5 ’ -CAGTAATTGATGTGAAAGTGTAG-3 ’ 50 Rv 5 ’ -GACCCTGTCTCCTAAAGAAA-3 ’ SRSF2 exon 1 Fw 5 ’ -GTGGACAACCTGACCTACCG-3 ’ 61 Rv 5 ’ -CCTCAGCCCCGTTTACCT-3 ’ Voso et al, Supplementary Figure 1 Oligonucleotide sequences and PCR conditions used for sequencing

2. Voso et al, Supplementary Figure 2 Exemplary sequencing reactions for all genes studied

3. Months from MPN diagnosis Probability (%) Time to Leukemic evolution SRSF2-mutatedSRSF2-wild type p=0.04 Voso et al, Supplementary Figure 3

4. Voso et al, Supplementary Table 1 Characteristics of patients with leukemias secondary to chronic myeloproliferative neoplasms Patient Characteristicsn (range) Median age (years, median, range)69.5 (54-81) Sex (M/F)8 / 8 Bone marrow blasts (%, median, range)37.5 (10-76) Primary MPN Polycytemia Vera Idiopatic Myelofibrosis Essential thrombocytemia Hypereosinophilic syndrome 86118611 Median latency between primary MPN and secondary leukemia diagnosis (median, range) 4.7 (1.4-15.5) Karyotype - Normal - Isolated chromosome 5 and/or 7 deletion - Trisomy 8 - Complex karyotype * 52185218 *Of 5 patients with a complex karyotype, 2 had 11q23 abnormalities and 3 had a chromosome 5 and/or 7 deletion

5. Patient Characteristics IDH1/2 -mut (n=15) DNMT3A R882-mut (n=16) SRSF2 P95-mut (n=15) Age at leukemic transformation (LT) > 60 yrs < 60yrs 5/11 0/4 2/12 0/4 5/11 0/4 Type of MPNPolycytemia Vera (PV) Idiopatic myelofibrosis HES or ET 2/7 3/6 0/2 1/8 * 1/6 0/2 2/7 2/6 1/2 Latency to LT< 5 yrs > 5 yrs 3/8 2/7 0/9 2/7 5/8 0/7 ** Treatment of MPNHydroxyurea (HU) alone HU + Radiotherapy (RT) HU+ Pipobroman +RT HU+ 6-mercaptopurine Cyclophosphamide RT + Chemotherapy for a previous solid tumor 4/10 1/1** 0/1 1/10 1/1** 0/1 0/2 5/10 0/1 Voso et al, Supplementary Table 2 Prevalence of mutations in patients with leukemias Secondary to chronic myeloproliferative neoplasms * One patient with a previous PV had synchronous IDH2 R140Q and DNMT3A R882H mutations ** p=0.025