Comparison of myeloid blast counts and variant allele frequencies of gene mutations in myelodysplastic syndrome with excess blasts and secondary acute myeloid leukemia

Secondary acute myeloid leukemia (sAML) is biologically and clinically distinct from de novo AML and shares specific genetic mutations with myelodysplastic syndromes (MDS). We retrospectively analyzed data from 295 adults with MDS or AML with mutational analysis by next-generation sequencing (NGS), and examined differences in functional grouping of mutations and relation between morphologic blast count and variant allele frequency (VAF) of mutations. Our analysis showed the distribution of mutations differed in MDS and AML. However, these differences largely disappeared when we compared MDS with excess blasts (MDS-EB) and sAML. VAF of mutations generally did not correlate with morphologic blast count and the distribution of VAF was similar above and below the 20% cutpoint. Complete remission (CR) rate was similar in MDS-EB and sAML following high intensity therapy and survival was also similar. These results support that MDS-EB and sAML have overlapping features and may represent a spectrum of the same disease.Key pointsThe distribution of genetic mutations is similar in myelodysplastic syndrome with excess blasts (MDS-EB) and secondary acute myeloid leukemia (sAML) regardless of morphologic blast count.Variant allele frequencies (VAFs) of gene mutations do not correlate well with morphologic blast counts, particularly in MDS-EB and sAML.Complete remission (CR) rate was similar in MDS-EB and sAML following high intensity or low intensity therapy.