1 4571 116 MYELOMONOCYTIC SKEWING IN CHRONIC MYELOMONOCYTIC LEUKEMIA: PHENOTYPIC, MOLECULAR AND BIOLOGIC FEATURES AND IMPACT ON SURVIVAL. BACKGROUND: MYELOMONOCYTIC SKEWING IS CONSIDERED AS A KEY PATHOPHYSIOLOGIC PHENOMENON IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), BUT ITS PREVALENCE AND POTENTIAL CORRELATION WITH PHENOTYPIC, GENOTYPIC, AND CLINICAL FEATURES ARE POORLY DEFINED. METHODS: SKEWED DIFFERENTIATION TOWARD THE MYELOMONOCYTIC OVER ERYTHROID COMMITMENT AS INDICATED BY AN INVERSE RATIO OF MYELOMONOCYTIC/ERYTHROID COLONIES WAS INVESTIGATED IN 146 PATIENTS WITH CMML BY SEMISOLID IN VITRO CULTURES. RESULTS: THERE WAS A HIGH PREVALENCE OF MYELOMONOCYTIC SKEWING IN PATIENTS WITH CMML (120/146, 82%); WHEREAS, THIS PHENOMENON WAS RARE IN NORMAL INDIVIDUALS (1/98, 1%). PATIENTS WITH CMML WITH MYELOMONOCYTIC SKEWING HAD HIGHER WHITE BLOOD CELL AND PERIPHERAL BLAST CELL COUNTS, AND LOWER PLATELET VALUES. THE NUMBER OF MUTATIONS IN GENES OF THE EPIGENETIC AND/OR SPLICING CATEGORY WAS HIGHER IN CMML PATIENTS WITH AS COMPARED WITH PATIENTS WITHOUT SKEWING. PATIENTS WITH MYELOMONOCYTIC SKEWING HAD MORE FREQUENTLY MUTATIONS IN RASOPATHY GENES AND HIGHER GROWTH FACTOR INDEPENDENT MYELOID COLONY FORMATION. INTERESTINGLY, THE LACK OF MYELOMONOCYTIC SKEWING DISCRIMINATED PATIENTS WITH CMML WITH A PARTICULARLY FAVORABLE PROGNOSIS (60 VS 19 MONTHS, P = .003) AND A MINIMAL RISK OF TRANSFORMATION. CONCLUSION: MYELOMONOCYTIC SKEWING AS DETERMINED BY SEMISOLID CULTURES CAN DISCRIMINATE SUBGROUPS OF PATIENTS WITH CMML WITH A DIFFERENT PHENOTYPE, A DIFFERENT GENOTYPE, AND A DIFFERENT PROGNOSIS. 2021 2 1070 25 CLONAL ARCHITECTURE OF CHRONIC MYELOMONOCYTIC LEUKEMIAS. GENOMIC STUDIES IN CHRONIC MYELOID MALIGNANCIES, INCLUDING MYELOPROLIFERATIVE NEOPLASMS (MPN), MYELODYSPLASTIC SYNDROMES (MDS), AND MPN/MDS, HAVE IDENTIFIED COMMON MUTATIONS IN GENES ENCODING SIGNALING, EPIGENETIC, TRANSCRIPTION, AND SPLICING FACTORS. IN THE PRESENT STUDY, WE INTERROGATED THE CLONAL ARCHITECTURE BY MUTATION-SPECIFIC DISCRIMINATION ANALYSIS OF SINGLE-CELL-DERIVED COLONIES IN 28 PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIAS (CMML), THE MOST FREQUENT MPN/MDS. THIS ANALYSIS REVEALS A LINEAR ACQUISITION OF THE STUDIED MUTATIONS WITH LIMITED BRANCHING THROUGH LOSS OF HETEROZYGOSITY. SERIAL ANALYSIS OF UNTREATED AND TREATED SAMPLES DEMONSTRATES A DYNAMIC ARCHITECTURE ON WHICH MOST CURRENT THERAPEUTIC APPROACHES HAVE LIMITED EFFECTS. THE MAIN DISEASE CHARACTERISTICS ARE EARLY CLONAL DOMINANCE, ARISING AT THE CD34(+)/CD38(-) STAGE OF HEMATOPOIESIS, AND GRANULOMONOCYTIC DIFFERENTIATION SKEWING OF MULTIPOTENT AND COMMON MYELOID PROGENITORS. COMPARISON OF CLONAL EXPANSIONS OF TET2 MUTATIONS IN MDS, MPN, AND CMML, TOGETHER WITH FUNCTIONAL INVALIDATION OF TET2 IN SORTED PROGENITORS, SUGGESTS A CAUSATIVE LINK BETWEEN EARLY CLONAL DOMINANCE AND SKEWED GRANULOMONOCYTIC DIFFERENTIATION. ALTOGETHER, EARLY CLONAL DOMINANCE MAY DISTINGUISH CMML FROM OTHER CHRONIC MYELOID NEOPLASMS WITH SIMILAR GENE MUTATIONS. 2013 3 4555 27 MUTATIONAL SPECTRUM ANALYSIS OF CHRONIC MYELOMONOCYTIC LEUKEMIA INCLUDES GENES ASSOCIATED WITH EPIGENETIC REGULATION: UTX, EZH2, AND DNMT3A. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), A MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASM, IS CHARACTERIZED BY MONOCYTIC PROLIFERATION, DYSPLASIA, AND PROGRESSION TO ACUTE MYELOID LEUKEMIA. CMML HAS BEEN ASSOCIATED WITH SOMATIC MUTATIONS IN DIVERSE RECENTLY IDENTIFIED GENES. WE ANALYZED 72 WELL-CHARACTERIZED PATIENTS WITH CMML (N = 52) AND CMML-DERIVED ACUTE MYELOID LEUKEMIA (N = 20) FOR RECURRENT CHROMOSOMAL ABNORMALITIES WITH THE USE OF ROUTINE CYTOGENETICS AND SINGLE NUCLEOTIDE POLYMORPHISM ARRAYS ALONG WITH COMPREHENSIVE MUTATIONAL SCREENING. CYTOGENETIC ABERRATIONS WERE PRESENT IN 46% OF CASES, WHEREAS SINGLE NUCLEOTIDE POLYMORPHISM ARRAY INCREASED THE DIAGNOSTIC YIELD TO 60%. AT LEAST 1 MUTATION WAS FOUND IN 86% OF ALL CASES; NOVEL UTX, DNMT3A, AND EZH2 MUTATIONS WERE FOUND IN 8%, 10%, AND 5.5% OF PATIENTS, RESPECTIVELY. TET2 MUTATIONS WERE PRESENT IN 49%, ASXL1 IN 43%, CBL IN 14%, IDH1/2 IN 4%, KRAS IN 7%, NRAS IN 4%, AND JAK2 V617F IN 1% OF PATIENTS. VARIOUS MUTANT GENOTYPE COMBINATIONS WERE OBSERVED, INDICATING MOLECULAR HETEROGENEITY IN CMML. OUR RESULTS SUGGEST THAT MOLECULAR DEFECTS AFFECTING DISTINCT PATHWAYS CAN LEAD TO SIMILAR CLINICAL PHENOTYPES. 2011 4 536 31 ASXL1 MUTATIONS PREDICT INFERIOR MOLECULAR RESPONSE TO NILOTINIB TREATMENT IN CHRONIC MYELOID LEUKEMIA. GENE MUTATIONS INDEPENDENT OF BCR::ABL1 HAVE BEEN IDENTIFIED IN NEWLY DIAGNOSED PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML) IN CHRONIC PHASE, WHEREBY MUTATIONS IN EPIGENETIC MODIFIER GENES WERE MOST COMMON. THESE FINDINGS PROMPTED THE SYSTEMATIC ANALYSIS OF PREVALENCE, DYNAMICS, AND PROGNOSTIC SIGNIFICANCE OF SUCH MUTATIONS, IN A CLINICALLY WELL-CHARACTERIZED PATIENT POPULATION OF 222 CML PATIENTS FROM THE TIGER STUDY (CML-V) BY TARGETED NEXT-GENERATION SEQUENCING COVERING 54 MYELOID LEUKEMIA-ASSOCIATED GENES. IN TOTAL, 53/222 CML PATIENTS (24%) CARRIED 60 MUTATIONS AT DIAGNOSIS WITH ASXL1 BEING MOST COMMONLY AFFECTED (N = 20). TO STUDY MUTATION DYNAMICS, LONGITUDINAL DEEP SEQUENCING ANALYSIS OF SERIAL SAMPLES WAS PERFORMED IN 100 PATIENTS AFTER 12, 24, AND 36 MONTHS OF THERAPY. TYPICAL PATTERNS OF CLONAL EVOLUTION INCLUDED ERADICATION, PERSISTENCE, AND EMERGENCE OF MUTATED CLONES. PATIENTS CARRYING AN ASXL1 MUTATION AT DIAGNOSIS SHOWED A LESS FAVORABLE MOLECULAR RESPONSE TO NILOTINIB TREATMENT, AS A MAJOR MOLECULAR RESPONSE (MMR) WAS ACHIEVED LESS FREQUENTLY AT MONTH 12, 18, AND 24 COMPARED TO ALL OTHER PATIENTS. PATIENTS WITH ASXL1 MUTATIONS WERE ALSO YOUNGER AND MORE FREQUENTLY FOUND IN THE HIGH RISK CATEGORY, SUGGESTING A CENTRAL ROLE OF CLONAL EVOLUTION ASSOCIATED WITH ASXL1 MUTATIONS IN CML PATHOGENESIS. 2022 5 4549 27 MUTATION ANALYSIS OF THERAPY-RELATED MYELOID NEOPLASMS. WE ANALYZED THE GENETIC MUTATION STATUS OF 13 PATIENTS WITH THERAPY-RELATED MYELOID NEOPLASMS (T-MN). CONSISTENT WITH PREVIOUS REPORTS, T-MN CELLS PREFERENTIALLY ACQUIRED MUTATIONS IN TP53 AND EPIGENETIC MODIFYING GENES, INSTEAD OF MUTATIONS IN TYROSINE KINASE AND SPLICEOSOME GENES. FURTHERMORE, WE COMPARED THE MUTATION STATUS OF THREE T-MN CELLS WITH EACH OF THE INITIAL LYMPHOID MALIGNANT CELLS, AND IDENTIFIED COMMON MUTATIONS AMONG T-MN AND THE INITIAL MALIGNANT CELLS IN TWO PATIENTS. IN A PATIENT WHO DEVELOPED CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AFTER FOLLICULAR LYMPHOMA (FL), TET2 MUTATION WAS IDENTIFIED IN BOTH CMML AND FL CELLS. NOTABLY, THE TET2 MUTATION WAS ALSO IDENTIFIED IN PERIPHERAL BLOOD CELLS IN THE DISEASE-FREE PERIOD WITH THE SAME ALLELIC FREQUENCY AS CMML AND FL CELLS, BUT NOT IN A GERM-LINE CONTROL, INDICATING THAT THE TET2 MUTATION OCCURRED SOMATICALLY IN THE INITIATING CLONE FOR BOTH MALIGNANT CELLS. ON THE OTHER HAND, A GERM-LINE MYB MUTATION WAS IDENTIFIED IN A PATIENT WHO DEVELOPED MYELODYSPLASTIC SYNDROMES (MDS) AFTER FL. THESE RESULTS SUGGEST THAT GERM-LINE DEPOSITION AND CLONAL HEMATOPOIESIS ARE CLOSELY ASSOCIATED WITH T-MN SUSCEPTIBILITY; HOWEVER, FURTHER ANALYSIS IS NECESSARY TO CLARIFY THE MECHANISM REQUIRED TO PROVIDE THE INITIATING CLONE WITH LINEAGE COMMITMENT AND CLONAL EXPANSION. 2018 6 3560 33 IMPACT OF CLINICAL, CYTOGENETIC, AND MOLECULAR PROFILES ON LONG-TERM SURVIVAL AFTER TRANSPLANTATION IN PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A HETEROGENEOUS GROUP OF CLONAL HEMATOPOIETIC MALIGNANCIES WITH VARIABLE CLINICAL AND MOLECULAR FEATURES. WE ANALYZED LONG-TERM RESULTS OF ALLOGENEIC HEMATOPOIETIC CELL TRANSPLANTATION IN PATIENTS WITH CMML AND DETERMINED CLINICAL AND MOLECULAR RISK FACTORS ASSOCIATED WITH OUTCOMES. DATA FROM 129 PATIENTS, AGED 7-74 (MEDIAN 55) YEARS, AT VARIOUS STAGES OF THE DISEASE AND TRANSPLANTED FROM RELATED OR UNRELATED DONORS WERE ANALYZED. USING A PANEL OF 75 GENES SOMATIC MUTATIONS PRESENT BEFORE HEMATOPOIETIC CELL TRANSPLANTATION WERE IDENTIFIED IN 52 PATIENTS. THE PROGRESSION-FREE SURVIVAL RATE AT 10 YEARS WAS 29%. THE MAJOR CAUSE OF DEATH WAS RELAPSE (32%), WHICH WAS SIGNIFICANTLY ASSOCIATED WITH ADVERSE CYTOGENETICS (HAZARD RATIO, 3.77; P=0.0002), CMML PROGNOSTIC SCORING SYSTEM (HAZARD RATIO, 14.3, P=0.01), AND MD ANDERSON PROGNOSTIC SCORES (HAZARD RATIO, 9.4; P=0.005). MORTALITY WAS ASSOCIATED WITH HIGH-RISK CYTOGENETICS (HAZARD RATIO, 1.88; P=0.01) AND HIGH HEMATOPOIETIC CELL TRANSPLANTATION COMORBIDITY INDEX (SCORE >/=4: HAZARD RATIO, 1.99; P=0.01). HIGH OVERALL MUTATION BURDEN (>/=10 MUTATIONS: HAZARD RATIO, 3.4; P=0.02), AND >/=4 MUTATED EPIGENETIC REGULATORY GENES (HAZARD RATIO 5.4; P=0.003) WERE LINKED TO RELAPSE. UNSUPERVISED CLUSTERING OF THE CORRELATION MATRIX REVEALED DISTINCT HIGH-RISK GROUPS WITH UNIQUE ASSOCIATIONS OF MUTATIONS AND CLINICAL FEATURES. CMML WITH A HIGH MUTATION BURDEN APPEARED TO BE DISTINCT FROM HIGH-RISK GROUPS DEFINED BY COMPLEX CYTOGENETICS. NEW TRANSPLANT STRATEGIES MUST BE DEVELOPED TO TARGET SPECIFIC DISEASE SUBGROUPS, STRATIFIED BY MOLECULAR PROFILING AND CLINICAL RISK FACTORS. 2020 7 5979 25 TET2 MUTATIONS ARE ASSOCIATED WITH SPECIFIC 5-METHYLCYTOSINE AND 5-HYDROXYMETHYLCYTOSINE PROFILES IN PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) HAS RECENTLY BEEN ASSOCIATED WITH A HIGH INCIDENCE OF DIVERSE MUTATIONS IN GENES SUCH AS TET2 OR EZH2 THAT ARE IMPLICATED IN EPIGENETIC MECHANISMS. WE HAVE PERFORMED GENOME-WIDE DNA METHYLATION ARRAYS AND MUTATIONAL ANALYSIS OF TET2, IDH1, IDH2, EZH2 AND JAK2 IN A GROUP OF 24 PATIENTS WITH CMML. 249 GENES WERE DIFFERENTIALLY METHYLATED BETWEEN CMML PATIENTS AND CONTROLS. USING INGENUITY PATHWAY ANALYSIS, WE IDENTIFIED ENRICHMENT IN A GENE NETWORK CENTERED AROUND PLC, JNK AND ERK SUGGESTING THAT THESE PATHWAYS, WHOSE DEREGULATION HAS BEEN RECENTLY DESCRIBED IN CMML, ARE AFFECTED BY EPIGENETIC MECHANISMS. MUTATIONS OF TET2, JAK2 AND EZH2 WERE FOUND IN 15 PATIENTS (65%), 4 PATIENTS (17%) AND 1 PATIENT (4%) RESPECTIVELY WHILE NO MUTATIONS IN THE IDH1 AND IDH2 GENES WERE IDENTIFIED. INTERESTINGLY, PATIENTS WITH WILD TYPE TET2 CLUSTERED SEPARATELY FROM PATIENTS WITH TET2 MUTATIONS, SHOWED A HIGHER DEGREE OF HYPERMETHYLATION AND WERE ASSOCIATED WITH HIGHER RISK KARYOTYPES. OUR RESULTS DEMONSTRATE THE PRESENCE OF ABERRANT DNA METHYLATION IN CMML AND IDENTIFIES TET2 MUTANT CMML AS A BIOLOGICALLY DISTINCT DISEASE SUBTYPE WITH A DIFFERENT EPIGENETIC PROFILE. 2012 8 4485 28 MOLECULAR SIMILARITY BETWEEN MYELODYSPLASTIC FORM OF CHRONIC MYELOMONOCYTIC LEUKEMIA AND REFRACTORY ANEMIA WITH RING SIDEROBLASTS. CHRONIC MYELOMONOCYTIC LEUKEMIA IS SIMILAR TO BUT A SEPARATE ENTITY FROM BOTH MYELOPROLIFERATIVE NEOPLASMS AND MYELODYSPLASTIC SYNDROMES, AND SHOWS EITHER MYELOPROLIFERATIVE OR MYELODYSPLASTIC FEATURES. WE ASK WHETHER THIS DISTINCTION MAY HAVE A MOLECULAR BASIS. WE ESTABLISHED THE GENE EXPRESSION PROFILES OF 39 SAMPLES OF CHRONIC MYELOMONOCYTIC LEUKEMIA (INCLUDING 12 CD34-POSITIVE) AND 32 CD34-POSITIVE SAMPLES OF MYELODYSPLASTIC SYNDROMES BY USING AFFYMETRIX MICROARRAYS, AND STUDIED THE STATUS OF 18 GENES BY SANGER SEQUENCING AND ARRAY-COMPARATIVE GENOMIC HYBRIDIZATION IN 53 SAMPLES. ANALYSIS OF 12 MRNAS FROM CHRONIC MYELOMONOCYTIC LEUKEMIA ESTABLISHED A GENE EXPRESSION SIGNATURE OF 122 PROBE SETS DIFFERENTIALLY EXPRESSED BETWEEN PROLIFERATIVE AND DYSPLASTIC CASES OF CHRONIC MYELOMONOCYTIC LEUKEMIA. AS COMPARED TO PROLIFERATIVE CASES, DYSPLASTIC CASES OVER-EXPRESSED GENES INVOLVED IN RED BLOOD CELL BIOLOGY. WHEN APPLIED TO 32 MYELODYSPLASTIC SYNDROMES, THIS GENE EXPRESSION SIGNATURE WAS ABLE TO DISCRIMINATE REFRACTORY ANEMIAS WITH RING SIDEROBLASTS FROM REFRACTORY ANEMIAS WITH EXCESS OF BLASTS. BY COMPARING MRNAS FROM THESE TWO FORMS OF MYELODYSPLASTIC SYNDROMES WE DERIVED A SECOND GENE EXPRESSION SIGNATURE. THIS SIGNATURE SEPARATED THE MYELODYSPLASTIC AND MYELOPROLIFERATIVE FORMS OF CHRONIC MYELOMONOCYTIC LEUKEMIAS. THESE RESULTS WERE VALIDATED USING TWO INDEPENDENT GENE EXPRESSION DATA SETS. WE FOUND THAT MYELODYSPLASTIC CHRONIC MYELOMONOCYTIC LEUKEMIAS ARE CHARACTERIZED BY MUTATIONS IN TRANSCRIPTION/EPIGENETIC REGULATORS (ASXL1, RUNX1, TET2) AND SPLICING GENES (SRSF2) AND THE ABSENCE OF MUTATIONS IN SIGNALING GENES. MYELODYSPLASTIC CHRONIC MYELOMONOCYTIC LEUKEMIAS AND REFRACTORY ANEMIAS WITH RING SIDEROBLASTS SHARE A COMMON EXPRESSION PROGRAM SUGGESTING THEY ARE PART OF A CONTINUUM, WHICH IS NOT TOTALLY EXPLAINED BY THEIR SIMILAR BUT NOT, HOWEVER, IDENTICAL MUTATION SPECTRUM. 2013 9 151 26 ABERRANT METHYLATION AND IMPAIRED EXPRESSION OF THE P15(INK4B) CELL CYCLE REGULATORY GENE IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). THE IMPORTANT CELL CYCLE REGULATORY GENE P15(INK4B) HAS BEEN SHOWN TO BE INACTIVATED IN ACUTE MYELOID LEUKEMIA AND MYELODYSPLASTIC SYNDROME. LITTLE IS KNOWN ABOUT THE EXPRESSION AND EPIGENETIC MODIFICATION OF THIS GENE IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) THAT BELONGS TO THE MYELODYSPLASTIC/MYELOPROLIFERATIVE DISORDERS (MDS/MPD) WITH A HIGH PROPORTION OF BLASTIC TRANSFORMATION. ANALYSIS OF BONE MARROW TREPHINES IN A SERIES OF 33 CMML CASES SHOWED AN ABERRANT P15(INK4B) GENE METHYLATION IN UP TO 58% OF CASES. METHYLATION WAS ANALYZED EMPLOYING DIFFERENT METHYLATION-SPECIFIC PCR AND GENOMIC SEQUENCING PROTOCOLS. IT TURNED OUT TO BE SPREAD OVER A BROAD AREA OF THE 5' REGION AND EXHIBITED SUBSTANTIAL HETEROGENEITY BETWEEN CASES AND EVEN IN INDIVIDUAL PATIENTS. THE DEGREE OF ABERRANT METHYLATION WAS CORRELATED WITH A REDUCED MRNA AS WELL AS REDUCED PROTEIN EXPRESSION, AND WAS ASSOCIATED WITH A HIGHER EXPRESSION OF DNA METHYLTRANSFERASE DNMT 3A. WE CONCLUDE THAT ABERRANT GENE METHYLATION IS A FREQUENT EVENT IN CMML THAT MIGHT CONTRIBUTE TO THE PATHOGENESIS OF THIS MDS/MPD. 2003 10 1628 39 DNMT3A AND TET2 DOMINATE CLONAL HEMATOPOIESIS AND DEMONSTRATE BENIGN PHENOTYPES AND DIFFERENT GENETIC PREDISPOSITIONS. AGE-ASSOCIATED CLONAL HEMATOPOIESIS CAUSED BY ACQUIRED MUTATIONS IN MYELOID CANCER-ASSOCIATED GENES IS HIGHLY PREVALENT IN THE NORMAL POPULATION. ITS ETIOLOGY, BIOLOGICAL IMPACT ON HEMATOPOIESIS, AND ONCOGENIC RISK IS POORLY DEFINED AT THIS TIME. TO GAIN INSIGHT INTO THIS PHENOMENON, WE ANALYZED A COHORT OF 2530 RELATED AND UNRELATED HEMATOLOGICALLY NORMAL INDIVIDUALS (AGES 55 TO 101 YEARS). WE USED A SENSITIVE GENE-TARGETED DEEP SEQUENCING APPROACH TO GAIN PRECISION ON THE EXACT PREVALENCE OF DRIVER MUTATIONS AND THE PROPORTIONS OF AFFECTED GENES. MUTATIONAL STATUS WAS CORRELATED WITH BIOLOGICAL PARAMETERS. WE REPORT A HIGHER OVERALL PREVALENCE OF DRIVER MUTATIONS (13.7%), WHICH OCCURRED MOSTLY (93%) IN DNMT3A OR TET2 AND WERE HIGHLY AGE-CORRELATED. MUTATION IN THESE 2 GENES HAD SOME DISTINCTIVE EFFECTS ON END POINTS. TET2 MUTATIONS WERE MORE AGE-DEPENDENT, ASSOCIATED WITH A MODEST NEUTROPENIC EFFECT (9%, P = .012), DEMONSTRATED FAMILIAL AGGREGATION, AND ASSOCIATED WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE. MUTATIONS IN DNMT3A HAD NO IMPACT ON BLOOD COUNTS OR INDICES. MUTATIONAL BURDEN OF BOTH GENES CORRELATED WITH X-INACTIVATION SKEWING BUT NO SIGNIFICANT ASSOCIATION WITH AGE-ADJUSTED TELOMERE LENGTH REDUCTION WAS DOCUMENTED. THE DISCORDANCE BETWEEN THE HIGH PREVALENCE OF MUTATIONS IN THESE 2 GENES AND THEIR LIMITED BIOLOGICAL IMPACT RAISE THE QUESTION OF THE POTENTIAL ROLE OF DYSREGULATED EPIGENETIC MODIFIERS IN NORMAL AGING HEMATOPOIESIS, WHICH MAY INCLUDE SUPPORT TO FAILING HEMATOPOIESIS. 2017 11 5665 38 SF3B1, RUNX1 AND TP53 MUTATIONS SIGNIFICANTLY IMPACT THE OUTCOME OF PATIENTS WITH LOWER-RISK MYELODYSPLASTIC SYNDROME. INTRODUCTION: PROGNOSIS OF PATIENTS WITH MYELODYSPLASTIC SYNDROME (MDS), PARTICULARLY THE GROUP WITH LOWER-RISK DISEASE (LR-MDS) IS VERY HETEROGENEOUS. SEVERAL STUDIES HAVE DESCRIBED THE PROGNOSTIC VALUE OF RECURRENT SOMATIC MUTATIONS IN MDS INCLUDING ALL RISK CATEGORIES. RECENTLY, THE INCORPORATION OF GENOMIC DATA TO CLINICAL PARAMETERS DEFINED THE NEW MOLECULAR INTERNATIONAL PROGNOSTIC SCORING SYSTEM (IPSS-M). MATERIALS AND METHODS: IN THIS STUDY, WE EVALUATED THE IMPACT OF MOLECULAR PROFILE IN A SERIES OF 181 PATIENTS WITH LR-MDS AND NON-PROLIFERATIVE CHRONIC MYELOMONOCYTIC LEUKEMIA. RESULTS: EPIGENETIC REGULATORS (TET2, ASXL1) AND SPLICING (SF3B1) WERE THE MOST RECURRENT MUTATED PATHWAYS. IN UNIVARIATE ANALYSIS, RUNX1 OR TP53 MUTATIONS CORRELATED WITH LOWER MEDIAN OVERALL SURVIVAL (OS). IN CONTRAST, SF3B1 MUTATION WAS ASSOCIATED WITH PROLONGED MEDIAN OS [95 MONTHS (95% IC, 32-157) VS. 33 MONTHS (95% CI, 19-46) IN UNMUTATED PATIENTS (P < 0.01)]. IN A MULTIVARIATE COX REGRESSION MODEL, RUNX1 MUTATIONS INDEPENDENTLY ASSOCIATED WITH SHORTER OS, WHILE SF3B1 MUTATION RETAINED ITS FAVORABLE IMPACT ON OUTCOME (HR: 0.24, 95% CI, 0.1-0.5; P = 0.001). IN ADDITION, TP53 OR RUNX1 MUTATIONS WERE IDENTIFIED AS PREDICTIVE COVARIATES FOR THE PROBABILITY OF LEUKEMIC PROGRESSION (P < 0.001). CONCLUSION: INCORPORATION OF MOLECULAR TESTING IN LR-MDS IDENTIFIED A SUBSET OF PATIENTS WITH EXPECTED POORER OUTCOME, EITHER DUE TO LOWER SURVIVAL OR PROBABILITY OF LEUKEMIC PROGRESSION. 2022 12 4547 16 MUTATION ALLELE BURDEN REMAINS UNCHANGED IN CHRONIC MYELOMONOCYTIC LEUKAEMIA RESPONDING TO HYPOMETHYLATING AGENTS. THE CYTIDINE ANALOGUES AZACYTIDINE AND 5-AZA-2'-DEOXYCYTIDINE (DECITABINE) ARE COMMONLY USED TO TREAT MYELODYSPLASTIC SYNDROMES, WITH OR WITHOUT A MYELOPROLIFERATIVE COMPONENT. IT REMAINS UNCLEAR WHETHER THE RESPONSE TO THESE HYPOMETHYLATING AGENTS RESULTS FROM A CYTOTOXIC OR AN EPIGENETIC EFFECT. IN THIS STUDY, WE ADDRESS THIS QUESTION IN CHRONIC MYELOMONOCYTIC LEUKAEMIA. WE DESCRIBE A COMPREHENSIVE ANALYSIS OF THE MUTATIONAL LANDSCAPE OF THESE TUMOURS, COMBINING WHOLE-EXOME AND WHOLE-GENOME SEQUENCING. WE IDENTIFY AN AVERAGE OF 14+/-5 SOMATIC MUTATIONS IN CODING SEQUENCES OF SORTED MONOCYTE DNA AND THE SIGNATURES OF THREE MUTATIONAL PROCESSES. SERIAL SEQUENCING DEMONSTRATES THAT THE RESPONSE TO HYPOMETHYLATING AGENTS IS ASSOCIATED WITH CHANGES IN DNA METHYLATION AND GENE EXPRESSION, WITHOUT ANY DECREASE IN THE MUTATION ALLELE BURDEN, NOR PREVENTION OF NEW GENETIC ALTERATION OCCURENCE. OUR FINDINGS INDICATE THAT CYTOSINE ANALOGUES RESTORE A BALANCED HAEMATOPOIESIS WITHOUT DECREASING THE SIZE OF THE MUTATED CLONE, ARGUING FOR A PREDOMINANTLY EPIGENETIC EFFECT. 2016 13 5911 25 TARGETED NEXT-GENERATION SEQUENCING IN MYELODYSPLASTIC SYNDROME AND CHRONIC MYELOMONOCYTIC LEUKEMIA AIDS DIAGNOSIS IN CHALLENGING CASES AND IDENTIFIES FREQUENT SPLICEOSOME MUTATIONS IN TRANSFORMED ACUTE MYELOID LEUKEMIA. OBJECTIVES: OPTIMAL INTEGRATION OF NEXT-GENERATION SEQUENCING (NGS) INTO CLINICAL PRACTICE IN HEMATOLOGIC MALIGNANCIES REMAINS UNCLEAR. WE EVALUATE THE UTILITY OF NGS IN MYELOID MALIGNANCIES. METHODS: A 42-GENE PANEL WAS USED TO SEQUENCE 109 CASES OF MYELODYSPLASTIC SYNDROME (MDS, N = 38), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML, N = 14), MYELOPROLIFERATIVE NEOPLASM (MPN, N = 24), AND MDS AND/OR MPN TRANSFORMED TO ACUTE MYELOID LEUKEMIA (AML, N = 33). RESULTS: AT LEAST ONE PATHOGENIC MUTATION WAS IDENTIFIED IN 74% OF CASES OF MDS, 100% OF CMMLS, AND 96% OF MPNS. IN CONTRAST, ONLY 47% OF CASES OF MDS (18/38) AND 7% (1/14) OF CMMLS EXHIBITED ABNORMAL CYTOGENETICS. IN DIAGNOSTICALLY DIFFICULT CASES OF MDS OR CMML WITH NORMAL CYTOGENETICS, NGS IDENTIFIED A PATHOGENIC MUTATION AND WAS CRITICAL IN ESTABLISHING THE CORRECT DIAGNOSIS. SPLICEOSOMAL GENES AND EPIGENETIC MODIFIERS WERE FREQUENTLY MUTATED. SPLICEOSOME MUTATIONS WERE ALSO FREQUENTLY DETECTED IN AML ARISING FROM MDS, CMML, OR MPN (39%) COMPARED WITH THE REPORTED RATE IN DE NOVO AML (7%-14%). CONCLUSIONS: IN DIFFICULT CASES OF MDS OR MPN, NGS FACILITATES DIAGNOSIS BY DETECTION OF GENE MUTATIONS TO CONFIRM CLONALITY, AND AMLS EVOLVING FROM MDS OR MPN CARRY FREQUENT MUTATIONS IN SPLICEOSOMAL GENES. 2016 14 4876 23 OVEREXPRESSION OF ARGINASE 1 IS LINKED TO DNMT3A AND TET2 MUTATIONS IN LOWER-GRADE MYELODYSPLASTIC SYNDROMES AND CHRONIC MYELOMONOCYTIC LEUKEMIA. IMMUNE DYSREGULATION IS A COMMON FEATURE OF MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), PARTICULARLY IN EARLY STAGES. HOWEVER, THE GENETIC BASIS REMAINS POORLY UNDERSTOOD. WE RECENTLY REPORTED THAT MACROPHAGES FROM MICE DEFICIENT IN TET METHYLCYTOSINE DIOXYGENASE 2 (TET2), A MODEL OF MDS/CMML, ARE HYPERINFLAMMATORY AND HAVE INCREASED EXPRESSION OF ARGINASE 1 (ARG1). IN MACROPHAGES AND MYELOID DERIVED SUPPRESSOR CELLS (MDSCS) EXPRESSION OF ARG1 CONTRIBUTES TO T-CELL SUPPRESSION AND IMMUNE EVASION BY L-ARGININE DEPLETION, IN THE SETTING OF CHRONIC INFLAMMATION AND CANCER. SINCE HUMAN MDS AND CMML ARE DRIVEN BY TET2 MUTATIONS AND ASSOCIATED WITH CHRONIC INFLAMMATION, WE HYPOTHESIZED THAT ARGINASE ENZYMATIC ACTIVITY AND ARG1 EXPRESSION WOULD BE INCREASED IN HUMAN MDS/CMML BONE MARROW. ELEVATED ARGINASE ACTIVITY WAS OBSERVED IN BONE MARROW MONONUCLEAR CELLS OF MDS AND CMML PATIENTS WITH LOWER-GRADE FEATURES. IMMUNOHISTOCHEMICAL STUDIES CONFIRMED THAT MYELOMONOCYTIC CELLS OVEREXPRESS ARG1. ADDITIONALLY, MUTATIONS IN THE EPIGENETIC REGULATORS TET2 AND DNMT3A CORRESPONDED TO HIGH ARG1 EXPRESSION AND ACTIVITY. THESE FINDINGS SUGGEST ARG1 IS A BIOMARKER OF IMMUNE DYSREGULATION IN EARLY MDS AND CMML. RECENT MURINE FINDINGS HAVE IMPLICATED TET2 AND DNMT3A IN REGULATION OF INNATE IMMUNITY. OUR STUDY SUGGESTS SIMILAR CHANGES MAY BE DRIVEN BY HUMAN TET2 AND DNMT3A MUTATIONS. 2018 15 4265 30 MICRO-RNA-125A MEDIATES THE EFFECTS OF HYPOMETHYLATING AGENTS IN CHRONIC MYELOMONOCYTIC LEUKEMIA. BACKGROUND: CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS AN AGGRESSIVE HEMATOPOIETIC MALIGNANCY THAT ARISES FROM HEMATOPOIETIC STEM AND PROGENITOR CELLS (HSPCS). PATIENTS WITH CMML ARE FREQUENTLY TREATED WITH EPIGENETIC THERAPEUTIC APPROACHES, IN PARTICULAR THE HYPOMETHYLATING AGENTS (HMAS), AZACITIDINE (AZA) AND DECITABINE (DEC). ALTHOUGH HMAS ARE BELIEVED TO MEDIATE THEIR EFFICACY VIA RE-EXPRESSION OF HYPERMETHYLATED TUMOR SUPPRESSORS, KNOWLEDGE ABOUT RELEVANT HMA TARGETS IS SCARCE. AS SILENCING OF TUMOR-SUPPRESSIVE MICRO-RNAS (MIRS) BY PROMOTER HYPERMETHYLATION IS A CRUCIAL STEP IN MALIGNANT TRANSFORMATION, WE ASKED FOR A ROLE OF MIRS IN HMA EFFICACY IN CMML. RESULTS: INITIALLY, WE PERFORMED GENOME-WIDE MIR-EXPRESSION PROFILING IN A KRAS(G12D)-INDUCED CMML MOUSE MODEL. SELECTED CANDIDATES WITH PROMINENTLY DECREASED EXPRESSION WERE VALIDATED BY QPCR IN CMML MICE AND HUMAN CMML PATIENTS. THESE EXPERIMENTS REVEALED THE CONSISTENT DECREASE IN MIR-125A, A MIR WITH PREVIOUSLY DESCRIBED TUMOR-SUPPRESSIVE FUNCTION IN MYELOID NEOPLASIAS. FURTHERMORE, WE SHOW THAT MIR-125A DOWNREGULATION IS CAUSED BY HYPERMETHYLATION OF ITS UPSTREAM REGION AND CAN BE REVERSED BY HMA TREATMENT. BY EMPLOYING BOTH LENTIVIRAL AND CRISPR/CAS9-BASED MIR-125A MODIFICATION, WE DEMONSTRATE THAT HMA-INDUCED MIR-125A UPREGULATION INDEED CONTRIBUTES TO MEDIATING THE ANTI-LEUKEMIC EFFECTS OF THESE DRUGS. THESE DATA WERE VALIDATED IN A CLINICAL CONTEXT, AS MIR-125A EXPRESSION INCREASED AFTER HMA TREATMENT IN CMML PATIENTS, A PHENOMENON THAT WAS PARTICULARLY PRONOUNCED IN CASES SHOWING CLINICAL RESPONSE TO THESE DRUGS. CONCLUSIONS: TAKEN TOGETHER, WE REPORT DECREASED EXPRESSION OF MIR-125A IN CMML AND DELINEATE ITS RELEVANCE AS MEDIATOR OF HMA EFFICACY WITHIN THIS NEOPLASIA. 2021 16 2462 26 EPIGENETIC THERAPY OF MYELODYSPLASTIC SYNDROMES CONNECTS TO CELLULAR DIFFERENTIATION INDEPENDENTLY OF ENDOGENOUS RETROELEMENT DEREPRESSION. BACKGROUND: MYELODYSPLASTIC SYNDROMES (MDS) AND ACUTE MYELOID LEUKAEMIA (AML) ARE CHARACTERISED BY ABNORMAL EPIGENETIC REPRESSION AND DIFFERENTIATION OF BONE MARROW HAEMATOPOIETIC STEM CELLS (HSCS). DRUGS THAT REVERSE EPIGENETIC REPRESSION, SUCH AS 5-AZACYTIDINE (5-AZA), INDUCE HAEMATOLOGICAL IMPROVEMENT IN HALF OF TREATED PATIENTS. ALTHOUGH THE MECHANISMS UNDERLYING THERAPY SUCCESS ARE NOT YET CLEAR, INDUCTION OF ENDOGENOUS RETROELEMENTS (ERES) HAS BEEN HYPOTHESISED. METHODS: USING RNA SEQUENCING (RNA-SEQ), WE COMPARED THE TRANSCRIPTION OF ERES IN BONE MARROW HSCS FROM A NEW COHORT OF MDS AND CHRONIC MYELOMONOCYTIC LEUKAEMIA (CMML) PATIENTS BEFORE AND AFTER 5-AZA TREATMENT WITH HSCS FROM HEALTHY DONORS AND AML PATIENTS. WE FURTHER EXAMINED ERE TRANSCRIPTION USING THE MOST COMPREHENSIVE ANNOTATION OF ERE-OVERLAPPING TRANSCRIPTS EXPRESSED IN HSCS, GENERATED HERE BY DE NOVO TRANSCRIPT ASSEMBLY AND SUPPORTED BY FULL-LENGTH RNA-SEQ. RESULTS: CONSISTENT WITH PRIOR REPORTS, WE FOUND THAT TREATMENT WITH 5-AZA INCREASED THE REPRESENTATION OF ERE-DERIVED RNA-SEQ READS IN THE TRANSCRIPTOME. HOWEVER, SUCH INCREASES WERE COMPARABLE BETWEEN TREATMENT RESPONSES AND FAILURES. THE EXTENDED VIEW OF HSC TRANSCRIPTIONAL DIVERSITY OFFERED BY DE NOVO TRANSCRIPT ASSEMBLY ARGUED AGAINST 5-AZA-RESPONSIVE ERES AS DETERMINANTS OF THE OUTCOME OF THERAPY. INSTEAD, IT UNCOVERED PRE-TREATMENT EXPRESSION AND ALTERNATIVE SPLICING OF DEVELOPMENTALLY REGULATED GENE TRANSCRIPTS AS PREDICTORS OF THE RESPONSE OF MDS AND CMML PATIENTS TO 5-AZA TREATMENT. CONCLUSIONS: OUR STUDY IDENTIFIES THE DEVELOPMENTALLY REGULATED TRANSCRIPTIONAL SIGNATURES OF PROTEIN-CODING AND NON-CODING GENES, RATHER THAN ERES, AS CORRELATES OF A FAVOURABLE RESPONSE OF MDS AND CMML PATIENTS TO 5-AZA TREATMENT AND OFFERS NOVEL CANDIDATES FOR FURTHER EVALUATION. 2019 17 2911 30 GENE EXPRESSION PROFILING OF LOSS OF TET2 AND/OR JAK2V617F MUTANT HEMATOPOIETIC STEM CELLS FROM MOUSE MODELS OF MYELOPROLIFERATIVE NEOPLASMS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLINICALLY CHARACTERIZED BY THE CHRONIC OVERPRODUCTION OF DIFFERENTIATED PERIPHERAL BLOOD CELLS AND THE GRADUAL EXPANSION OF MALIGNANT INTRAMEDULLARY/EXTRAMEDULLARY HEMATOPOIESIS. IN MPNS MUTATIONS IN JAK2 MPL OR CALR ARE DETECTED MUTUALLY EXCLUSIVE IN MORE THAN 90% OF CASES [1,2]. MUTATIONS IN THEM LEAD TO THE ABNORMAL ACTIVATION OF JAK/STAT SIGNALING AND THE AUTONOMOUS GROWTH OF DIFFERENTIATED CELLS THEREFORE THEY ARE CONSIDERED AS "DRIVER" GENE MUTATIONS. IN ADDITION TO THE ABOVE DRIVER GENE MUTATIONS MUTATIONS IN EPIGENETIC REGULATORS SUCH AS TET2 DNMT3A ASXL1 EZH2 OR IDH1/2 ARE DETECTED IN ABOUT 5%-30% OF CASES RESPECTIVELY [3]. MUTATIONS IN TET2 DNMT3A EZH2 OR IDH1/2 COMMONLY CONFER THE INCREASED SELF-RENEWAL CAPACITY ON NORMAL HEMATOPOIETIC STEM CELLS (HSCS) BUT THEY DO NOT LEAD TO THE AUTONOMOUS GROWTH OF DIFFERENTIATED CELLS AND ONLY EXHIBIT SUBTLE CLINICAL PHENOTYPES [4,6-8,5]. IT WAS UNCLEAR HOW MUTATIONS IN SUCH EPIGENETIC REGULATORS INFLUENCED ABNORMAL HSCS WITH DRIVER GENE MUTATIONS HOW THEY INFLUENCED THE DISEASE PHENOTYPE OR WHETHER A SINGLE DRIVER GENE MUTATION WAS SUFFICIENT FOR THE INITIATION OF HUMAN MPNS. THEREFORE WE FOCUSED ON JAK2V617F AND LOSS OF TET2-THE FORMER AS A REPRESENTATIVE OF DRIVER GENE MUTATIONS AND THE LATTER AS A REPRESENTATIVE OF MUTATIONS IN EPIGENETIC REGULATORS-AND EXAMINED THE INFLUENCE OF SINGLE OR DOUBLE MUTATIONS ON HSCS (LINEAGE(-)SCA-1(+)C-KIT(+) CELLS (LSKS)) BY FUNCTIONAL ANALYSES AND MICROARRAY WHOLE-GENOME EXPRESSION ANALYSES [9]. GENE EXPRESSION PROFILING SHOWED THAT THE HSC FINGERPRINT GENES [10] WAS STATISTICALLY EQUALLY ENRICHED IN TET2-KNOCKDOWN-LSKS BUT NEGATIVELY ENRICHED IN JAK2V617F-LSKS COMPARED TO THAT IN WILD-TYPE-LSKS. DOUBLE-MUTANT-LSKS SHOWED THE SAME TENDENCY AS JAK2V617F-LSKS IN TERMS OF THEIR HSC FINGERPRINT GENES BUT THE EXPRESSION OF INDIVIDUAL GENES DIFFERED BETWEEN THE TWO GROUPS. AMONG 245 HSC FINGERPRINT GENES 100 WERE MORE HIGHLY EXPRESSED IN DOUBLE-MUTANT-LSKS THAN IN JAK2V617F-LSKS. THESE ALTERED GENE EXPRESSIONS MIGHT PARTLY EXPLAIN THE MECHANISMS OF INITIATION AND PROGRESSION OF MPNS WHICH WAS OBSERVED IN THE FUNCTIONAL ANALYSES [9]. HERE WE DESCRIBE GENE EXPRESSION PROFILES DEPOSITED AT THE GENE EXPRESSION OMNIBUS (GEO) UNDER THE ACCESSION NUMBER GSE62302 INCLUDING EXPERIMENTAL METHODS AND QUALITY CONTROL ANALYSES. 2015 18 2277 29 EPIGENETIC REGULATION BY ASXL1 IN MYELOID MALIGNANCIES. MYELOID MALIGNANCIES ARE CLONAL HEMATOPOIETIC DISORDERS THAT ARE COMPRISED OF A SPECTRUM OF GENETICALLY HETEROGENEOUS DISORDERS, INCLUDING MYELODYSPLASTIC SYNDROMES (MDS), MYELOPROLIFERATIVE NEOPLASMS (MPN), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), AND ACUTE MYELOID LEUKEMIA (AML). MYELOID MALIGNANCIES ARE CHARACTERIZED BY EXCESSIVE PROLIFERATION, ABNORMAL SELF-RENEWAL, AND/OR DIFFERENTIATION DEFECTS OF HEMATOPOIETIC STEM CELLS (HSCS) AND MYELOID PROGENITOR CELLS HEMATOPOIETIC STEM/PROGENITOR CELLS (HSPCS). MYELOID MALIGNANCIES CAN BE CAUSED BY GENETIC AND EPIGENETIC ALTERATIONS THAT PROVOKE KEY CELLULAR FUNCTIONS, SUCH AS SELF-RENEWAL, PROLIFERATION, BIASED LINEAGE COMMITMENT, AND DIFFERENTIATION. ADVANCES IN NEXT-GENERATION SEQUENCING LED TO THE IDENTIFICATION OF MULTIPLE MUTATIONS IN MYELOID NEOPLASMS, AND MANY NEW GENE MUTATIONS WERE IDENTIFIED AS KEY FACTORS IN DRIVING THE PATHOGENESIS OF MYELOID MALIGNANCIES. THE POLYCOMB PROTEIN ASXL1 WAS IDENTIFIED TO BE FREQUENTLY MUTATED IN ALL FORMS OF MYELOID MALIGNANCIES, WITH MUTATIONAL FREQUENCIES OF 20%, 43%, 10%, AND 20% IN MDS, CMML, MPN, AND AML, RESPECTIVELY. SIGNIFICANTLY, ASXL1 MUTATIONS ARE ASSOCIATED WITH A POOR PROGNOSIS IN ALL FORMS OF MYELOID MALIGNANCIES. THE FACT THAT ASXL1 MUTATIONS ARE ASSOCIATED WITH POOR PROGNOSIS IN PATIENTS WITH CMML, MDS, AND AML, POINTS TO THE POSSIBILITY THAT ASXL1 MUTATION IS A KEY FACTOR IN THE DEVELOPMENT OF MYELOID MALIGNANCIES. THIS REVIEW SUMMARIZES THE RECENT ADVANCES IN UNDERSTANDING MYELOID MALIGNANCIES WITH A SPECIFIC FOCUS ON ASXL1 MUTATIONS. 2023 19 1039 31 CLINICAL AND BIOLOGICAL IMPLICATIONS OF DRIVER MUTATIONS IN MYELODYSPLASTIC SYNDROMES. MYELODYSPLASTIC SYNDROMES (MDS) ARE A HETEROGENEOUS GROUP OF CHRONIC HEMATOLOGICAL MALIGNANCIES CHARACTERIZED BY DYSPLASIA, INEFFECTIVE HEMATOPOIESIS AND A VARIABLE RISK OF PROGRESSION TO ACUTE MYELOID LEUKEMIA. SEQUENCING OF MDS GENOMES HAS IDENTIFIED MUTATIONS IN GENES IMPLICATED IN RNA SPLICING, DNA MODIFICATION, CHROMATIN REGULATION, AND CELL SIGNALING. WE SEQUENCED 111 GENES ACROSS 738 PATIENTS WITH MDS OR CLOSELY RELATED NEOPLASMS (INCLUDING CHRONIC MYELOMONOCYTIC LEUKEMIA AND MDS-MYELOPROLIFERATIVE NEOPLASMS) TO EXPLORE THE ROLE OF ACQUIRED MUTATIONS IN MDS BIOLOGY AND CLINICAL PHENOTYPE. SEVENTY-EIGHT PERCENT OF PATIENTS HAD 1 OR MORE ONCOGENIC MUTATIONS. WE IDENTIFY COMPLEX PATTERNS OF PAIRWISE ASSOCIATION BETWEEN GENES, INDICATIVE OF EPISTATIC INTERACTIONS INVOLVING COMPONENTS OF THE SPLICEOSOME MACHINERY AND EPIGENETIC MODIFIERS. COUPLED WITH INFERENCES ON SUBCLONAL MUTATIONS, THESE DATA SUGGEST A HYPOTHESIS OF GENETIC "PREDESTINATION," IN WHICH EARLY DRIVER MUTATIONS, TYPICALLY AFFECTING GENES INVOLVED IN RNA SPLICING, DICTATE FUTURE TRAJECTORIES OF DISEASE EVOLUTION WITH DISTINCT CLINICAL PHENOTYPES. DRIVER MUTATIONS HAD EQUIVALENT PROGNOSTIC SIGNIFICANCE, WHETHER CLONAL OR SUBCLONAL, AND LEUKEMIA-FREE SURVIVAL DETERIORATED STEADILY AS NUMBERS OF DRIVER MUTATIONS INCREASED. THUS, ANALYSIS OF ONCOGENIC MUTATIONS IN LARGE, WELL-CHARACTERIZED COHORTS OF PATIENTS ILLUSTRATES THE INTERCONNECTIONS BETWEEN THE CANCER GENOME AND DISEASE BIOLOGY, WITH CONSIDERABLE POTENTIAL FOR CLINICAL APPLICATION. 2013 20 4557 21 MUTATIONS IN ASXL1 ARE ASSOCIATED WITH POOR PROGNOSIS ACROSS THE SPECTRUM OF MALIGNANT MYELOID DISEASES. THE ASXL1 GENE IS ONE OF THE MOST FREQUENTLY MUTATED GENES IN MALIGNANT MYELOID DISEASES. THE ASXL1 PROTEIN BELONGS TO PROTEIN COMPLEXES INVOLVED IN THE EPIGENETIC REGULATION OF GENE EXPRESSION. ASXL1 MUTATIONS ARE FOUND IN MYELOPROLIFERATIVE NEOPLASMS (MPN), MYELODYSPLASTIC SYNDROMES (MDS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND ACUTE MYELOID LEUKEMIA (AML). THEY ARE GENERALLY ASSOCIATED WITH SIGNS OF AGGRESSIVENESS AND POOR CLINICAL OUTCOME. BECAUSE OF THIS, A SYSTEMATIC DETERMINATION OF ASXL1 MUTATIONAL STATUS IN MYELOID MALIGNANCIES SHOULD HELP IN PROGNOSIS ASSESSMENT. 2012