Patient was initially diagnosed with low-risk myelodysplastic syndrome-refractory cytopenias and multilineage dysplasia (MDS-RCMD), progressed to AML after failing hypomethylating agent therapy.
Recurrent deletions and somatic mutations in TET2, a gene involved in epigenetic regulation, have been reported in about 20% of adult patients with myelodysplastic syndrome.
Here we demonstrate that SF3B1 mutation(s) in our cohort of MDS patients with ring sideroblasts can arise from CD34(+)CD38(-)CD45RA(-)CD90(+)CD49f(+) HSCs and is an initiating event in disease pathogenesis.
In conclusion, we suggest screening for GATA2 mutations in pediatric myelodysplastic syndrome, preferentially in patients with impaired B-cell homeostasis in bone marrow and peripheral blood (low number of progenitors, intronRSS-Kde recombination excision circles and naïve cells).
The most common mutations found in MDS occur in genes involved in RNA splicing (including SF3B1, SRSF2, U2AF1, and ZRSR2) and epigenetic modification (including TET2, ASXL1, and DNMT3A).
Recent studies are shedding light on the molecular basis of myelodysplasia and how mutations and epimutations can induce and promote this neoplastic process through aberrant transcription factor function (RUNX1, ETV6, TP53), kinase signalling (FLT3, NRAS, KIT, CBL) and epigenetic deregulation (TET2, IDH1/2, DNMT3A, EZH2, ASXL1, SF3B1, U2AF1, SRSF2, ZRSR2).
Over the past few years, large-scale genomic studies of patients with myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML) have unveiled recurrent somatic mutations in genes involved in epigenetic regulation (DNMT3A, IDH1/2, TET2, ASXL1, EZH2 and MLL) and the spliceosomal machinery (SF3B1, U2AF1, SRSF2, ZRSR2, SF3A1, PRPF40B, U2AF2, and SF1).
Although often healthy in childhood, carriers of defective GATA2 alleles develop progressive loss of mononuclear cells (dendritic cells, monocytes, B and Natural Killer lymphocytes), elevated FLT3 ligand, and a 90% risk of clinical complications, including progression to myelodysplastic syndrome (MDS) by 60 years of age.
We found that blast phase of PV was characterized by overt myelodysplasia (n = 51, 88%); moderate to severe myelofibrosis (33 of 45, 73%); an abnormal karyotype (n = 51, 88%) that was often complex karyotype (n = 42, 72%); and gene mutations involving TP53 (55%), TET2 (27%), and DNMT3A (25%).
To assess the impact of spliceosome mutations on splicing and to identify common pathways/genes affected by distinct mutations, we performed RNA-sequencing of MDS bone marrow samples harboring spliceosome mutations (including hotspot alterations of SF3B1, SRSF2 and U2AF1; small deletions of SRSF2 and truncating mutations of ZRSR2), and devoid of other common co-occurring mutations.
Furthermore, SF3B1 mutations are independent predictors of favorable clinical outcome, and their incorporation into stratification systems might improve risk assessment in MDS.
Patient was initially diagnosed with low-risk myelodysplastic syndrome-refractory cytopenias and multilineage dysplasia (MDS-RCMD), progressed to AML after failing hypomethylating agent therapy.
Significantly enriched in high-risk MDS (in comparison to low-risk MDS), TP53, GATA2, KRAS, RUNX1, STAG2, ASXL1, ZRSR2 and TET2 mutations (type 2) had a weaker impact on sAML progression and overall survival than type-1 mutations.
In the phase III MDS-005 study of patients with lower-risk, non-del(5q) myelodysplastic syndromes, lenalidomide was associated with a higher rate of ≥ 8 weeks red blood cell transfusion independence (RBC-TI) compared with placebo, but also with a higher risk of hematologic adverse events (AEs).
From this analysis, we identified a novel case of a donor-derived myelodysplastic syndrome in an HSCT recipient that is consistent with clonal evolution of TET2-mutated clonal hematopoiesis of indeterminate potential (CHIP) within the donor.
Another significant advance in MDS pathogenesis research is the recent identification of mutations in genes encoding transcription factors implicated in hematopoiesis and proteins involved in splicing (SF3B1), methylation (DNMT3A), regulation of methylation (TET2 and IDH), DNA conformation (EZH2 and ASXL1) and differentiation (N- and K-RAS).