1 6366 122 THE ROLE OF METHYLATION IN CML. METHYLATION OF THE PROXIMAL PROMOTER OF THE ABL1 ONCOGENE IS COMMON EPIGENETIC ALTERATION ASSOCIATED WITH CLINICAL PROGRESSION OF CHRONIC MYELOID LEUKEMIA (CML). IN PRESENTED STUDY WE QUERIED WHETHER BOTH THE PH'-ASSOCIATED AND NORMAL ABL1 ALLELES UNDERGO METHYLATION; WHAT MAY BE THE PROPORTION OF HEMATOPOIETIC PROGENITORS BEARING METHYLATED ABL1 PROMOTERS IN CHRONIC VERSUS ACUTE PHASE DISEASE; WHETHER METHYLATION AFFECTS THE PROMOTER UNIFORMLY OR IN PATCHES WITH DISCRETE CLINICAL RELEVANCE; AND, FINALLY WHETHER METHYLATION OF ABL1 REFLECTS A GENERALIZED PROCESS OR IS GENE-SPECIFIC. TO ADDRESS THESE ISSUES, THE TECHNIQUE OF METHYLATION-SPECIFIC PCR AND BISULFITE-SEQUENCING WAS ADAPTED TO STUDY THE REGULATORY REGIONS OF ABL1 AND OTHER GENES. IN CELL LINES ESTABLISHED FROM CML BLAST CRISIS, WHICH ONLY CARRY A SINGLE ABL1 ALLELE NESTED WITHIN THE BCR-ABL FUSION GENE, ABL1 PROMOTERS WERE UNIVERSALLY METHYLATED. IN CLINICAL SAMPLES FROM PATIENTS AT ADVANCED STAGES OF THE DISEASE, BOTH METHYLATED AND UNMETHYLATED PROMOTER ALLELES WERE DETECTABLE. IN COLONIES DERIVED FROM SINGLE HEMATOPOIETIC PROGENITORS METHYLATED AND UNMETHYLATED PROMOTER ALLELES WERE REVEALED AS WELL. ABL1 METHYLATION WAS WAS NOTED IN THE VAST MAJORITY OF COLONIES FROM BLAST CRISIS, BUT NOT CHRONIC-PHASE CML. IT WAS SHOWN FINALLY THAT ABL1 METHYLATION DOES NOT REFLECT A GENERALIZED PROCESS AND MAY BE UNIQUE AMONG DNA REPAIR/GENOTOXIC STRESS RESPONSE GENES. THESE DATA SUGGEST THAT SPECIFIC METHYLATION OF THE PH'-ASSOCIATED ABL1 ALLELE ACCOMPANIES CLONAL EVOLUTION IN CML. 2000 2 163 116 ABL1 METHYLATION IS A DISTINCT MOLECULAR EVENT ASSOCIATED WITH CLONAL EVOLUTION OF CHRONIC MYELOID LEUKEMIA. METHYLATION OF THE PROXIMAL PROMOTER OF THE ABL1 ONCOGENE IS A COMMON EPIGENETIC ALTERATION ASSOCIATED WITH CLINICAL PROGRESSION OF CHRONIC MYELOID LEUKEMIA (CML). IN THIS STUDY WE QUERIED WHETHER BOTH THE PH'-ASSOCIATED AND NORMAL ABL1 ALLELES UNDERGO METHYLATION; WHAT MAY BE THE PROPORTION OF HEMATOPOIETIC PROGENITORS BEARING METHYLATED ABL1 PROMOTERS IN CHRONIC VERSUS ACUTE PHASE DISEASE; WHETHER METHYLATION AFFECTS THE PROMOTER UNIFORMLY OR IN PATCHES WITH DISCRETE CLINICAL RELEVANCE; AND, FINALLY, WHETHER METHYLATION OF ABL1 REFLECTS A GENERALIZED PROCESS OR IS GENE-SPECIFIC. TO ADDRESS THESE ISSUES, WE ADAPTED THE TECHNIQUES OF METHYLATION-SPECIFIC PCR AND BISULFITE-SEQUENCING TO STUDY THE REGULATORY REGIONS OF ABL1 AND OTHER GENES WITH A ROLE IN DNA REPAIR OR GENOTOXIC STRESS RESPONSE. IN CELL LINES ESTABLISHED FROM CML BLAST CRISIS, WHICH ONLY CARRY A SINGLE ABL1 ALLELE NESTED WITHIN THE BCR-ABL FUSION GENE, ABL1 PROMOTERS WERE UNIVERSALLY METHYLATED. BY CONTRAST, IN CLINICAL SAMPLES FROM PATIENTS AT ADVANCED STAGES OF DISEASE, BOTH METHYLATED AND UNMETHYLATED PROMOTER ALLELES WERE DETECTABLE. TO DISTINGUISH BETWEEN ALLELE-SPECIFIC METHYLATION AND A MIXED CELL POPULATION PATTERN, WE STUDIED THE METHYLATION STATUS OF ABL1 IN COLONIES DERIVED FROM SINGLE HEMATOPOIETIC PROGENITORS. OUR RESULTS SHOWED THAT BOTH METHYLATED AND UNMETHYLATED PROMOTER ALLELES COEXISTED IN THE SAME COLONY. FURTHERMORE, ABL1 METHYLATION WAS NOTED IN THE VAST MAJORITY OF COLONIES FROM BLAST CRISIS, BUT NOT CHRONIC-PHASE CML. BOTH CELL LINES AND CLINICAL SAMPLES FROM ACUTE-PHASE CML SHOWED NEARLY UNIFORM HYPERMETHYLATION ALONG THE PROMOTER REGION. FINALLY, WE SHOWED THAT ABL1 METHYLATION DOES NOT REFLECT A GENERALIZED PROCESS AND MAY BE UNIQUE AMONG DNA REPAIR/GENOTOXIC STRESS RESPONSE GENES. OUR DATA SUGGEST THAT SPECIFIC METHYLATION OF THE PH'-ASSOCIATED ABL1 ALLELE ACCOMPANIES CLONAL EVOLUTION IN CML. 1999 3 3530 42 IMATINIB (ST1571) PROVIDES ONLY LIMITED SELECTIVITY FOR CML CELLS AND TREATMENT MIGHT BE COMPLICATED BY SILENT BCR-ABL GENES. VERY PROMISING RESULTS HAVE BEEN OBTAINED IN CLINICAL TRIALS ON CHRONIC-PHASE CHRONIC MYELOID LEUKEMIA (CP-CML) PATIENTS TREATED WITH IMATINIB MESYLATE (IM; GLEEVECR, STI571), A BCR-ABL TYROSINE KINASE INHIBITOR. HOWEVER, WE FOUND THAT IM CAUSED CONSIDERABLE INHIBITION OF NORMAL HEMATOPOIETIC PROGENITOR CELLS UPON TREATING CONTROL BONE MARROW (BM) CULTURES. IN VITRO IM TREATMENT GAVE A DECREASE IN THE YIELD AND SIZE OF COLONIES FROM BM OF UNTREATED CP-CML PATIENTS THAT WAS ONLY TWO TO THREE TIMES THAT FROM THE NORMAL SAMPLES. MOREOVER, ABOUT 30% OF MYELOID PROGENITORS (CFU-GM) FROM CML BM STILL FORMED COLONIES IN THE PRESENCE OF IM, MOST OF WHICH HAD BCR-ABL RNA. ABOUT HALF OF THESE TREATED COLONIES ALSO DISPLAYED METHYLATION OF THE INTERNAL ABL PA PROMOTER, A CML-SPECIFIC EPIGENETIC ALTERATION, WHICH WAS USED IN THIS STUDY AS A MARKER FOR BCR-ABL TRANSLOCATION-CONTAINING CELLS. HOWEVER, ~5-8% OF THE TREATED OR THE UNTREATED CML BM-DERIVED COLONIES HAD NO DETECTABLE BCR-ABL RNA BY TWO OR THREE ROUNDS OF RT-PCR DESPITE BEING POSITIVE FOR THE INTERNAL STANDARD RNA AND DISPLAYING HALLMARKS OF CML, EITHER T(9;22)(Q34;QL 1) OR ABL PA METHYLATION. OUR RESULTS INDICATE THAT IM IS ONLY PARTIALLY SPECIFIC FOR CML PROGENITOR CELLS COMPARED TO NORMAL HEMATOPOIETIC PROGENITOR CELLS AND SUGGEST THAT SOME CML CELLS MAY HAVE A SILENT BCR-ABL ONCOGENE THAT COULD INTERFERE WITH THERAPY. 2003 4 4988 36 PATTERNS OF HEMATOPOIETIC LINEAGE INVOLVEMENT IN CHILDREN WITH NEUROFIBROMATOSIS TYPE 1 AND MALIGNANT MYELOID DISORDERS. CHILDREN WITH NEUROFIBROMATOSIS TYPE 1 (NF1) ARE AT INCREASED RISK OF DEVELOPING MALIGNANT MYELOID DISORDERS, PARTICULARLY JUVENILE CHRONIC MYELOGENOUS LEUKEMIA/JUVENILE MYELOMONOCYTIC LEUKEMIA (JCML/JMML). WE INVESTIGATED BONE MARROWS FROM 11 SUCH PATIENTS (8 BOYS AND 3 GIRLS) AND DETECTED ALLELIC LOSSES AT THE NF1 LOCUS IN 4 OF THEM AND PROBABLE LOSSES IN 2 OTHERS. TO DETERMINE WHICH HEMATOPOIETIC CELL LINEAGES WERE DERIVED FROM THE ABNORMAL CLONES, EPSTEIN-BARR VIRUS (EBV)-TRANSFORMED CELL LINES AND CD34+ CELLS WERE ANALYZED FROM 3 CHILDREN WITH JCML WITH ALLELIC LOSSES IN UNFRACTIONATED MARROW. CD34 CELLS FROM THESE 3 PATIENTS LACKED THE NORMAL NF1 ALLELE, WHEREAS EBV CELL LINES RETAINED IT. ERYTHROBLASTS PLUCKED FROM THE BURST-FORMING UNIT-ERYTHROID COLONIES OF ONE OF THESE CHILDREN LACKED THE NORMAL NF1 ALLELE. WE ALSO STUDIED A 10-MONTH-OLD BOY WITH NF1 WHO DEVELOPED AN UNUSUAL MYELOPROLIFERATIVE SYNDROME. HIS BONE MARROW AND EBV CELL LINE BOTH SHOWED LOSS OF THE NORMAL NF1 ALLELE. IN OUR SERIES AND IN THE LITERATURE, MALE SEX AND MATERNAL TRANSMISSION OF NF1 WERE ASSOCIATED WITH THE HIGHEST RISK OF MYELOID LEUKEMIA. THESE DATA (1) PROVIDE STRONG GENETIC EVIDENCE THAT NF1 FUNCTIONS AS A TUMOR-SUPPRESSOR IN EARLY MYELOPOIESIS, (2) CONFIRM THE CLONAL NATURE OF JCML/JMML, (3) SUGGEST THAT THE ELEVATION IN FETAL HEMOGLOBIN SEEN IN JCML/JMML IS A RESULT OF PRIMARY INVOLVEMENT OF ERYTHROID PROGENITORS IN THE MALIGNANT CLONE, (4) SHOW CONSISTENT LOSS OF NF1 IN THE CD34 CELLS OF AFFECTED CHILDREN AND SHOW THAT THE MALIGNANT CLONE MAY ALSO GIVE RISE TO PRE-B CELLS IN SOME CASES, AND (5) IMPLICATE EPIGENETIC FACTORS IN THE DEVELOPMENT OF LEUKEMIA IN CHILDREN WITH NF1. 1996 5 4571 21 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 6 1070 27 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 7 162 40 ABL1 METHYLATION IN PH-POSITIVE ALL IS EXCLUSIVELY ASSOCIATED WITH THE P210 FORM OF BCR-ABL. IN HUMAN PH-POSITIVE LEUKEMIA THERE IS A CLEAR ASSOCIATION OF DIFFERENT FORMS OF THE BCR-ABL ONCOGENE WITH DISTINCT TYPES OF LEUKEMIA. THE P190 FORM OF BCR-ABL IS RARELY OBSERVED IN CHRONIC MYELOID LEUKEMIA (CML) BUT IS PRESENT IN 50% OF PH-POSITIVE ACUTE LYMPHOBLASTIC LEUKEMIA (ALL). IN CONTRAST, THE P210 FORM IS OBSERVED BOTH IN CML AND 50% OF PH-POSITIVE ALL. METHYLATION OF THE PROXIMAL PROMOTER OF THE ABL1 GENE HAS BEEN SHOWN TO BE A NEARLY UNIVERSAL EVENT ASSOCIATED WITH CLINICAL PROGRESSION OF CML. THIS RAISES THE QUESTION OF WHETHER METHYLATION OF THE ABL1 PROMOTER IS AN EPIGENETIC MODIFICATION ALSO ASSOCIATED WITH PH-POSITIVE ALL. TO STUDY THIS ISSUE, WE USED METHYLATION-SPECIFIC PCR AND BISULFITE SEQUENCING TO DETERMINE THE METHYLATION STATUS OF THE ABL1 PROMOTER IN 18 PH-POSITIVE ALL SAMPLES. WE REPORT HERE THAT GENE-SPECIFIC ABL1 PROMOTER METHYLATION IS ASSOCIATED MAINLY WITH THE P210 FORM OF BCR-ABL AND NOT THE P190 FORM. WHILE SIX OUT OF THE SEVEN P210-POSITIVE ALL SAMPLES HAD ABL1 PROMOTER METHYLATION, NONE OF THE 11 P190-POSITIVE ALL SAMPLES DEMONSTRATED ABL1 PROMOTER METHYLATION. IN ADDITION, WE ESTIMATED THE EXTENT AND RELATIVE ABUNDANCE OF ABL1 PROMOTER METHYLATION IN SEVERAL PH-POSITIVE ALL SAMPLES AND COMPARED IT TO THE METHYLATION PATTERN IN CHRONIC, ACCELERATED AND BLASTIC CRISIS PHASES OF CML. WE PUT FORTH A MODEL THAT CORRELATES THE DIFFERENT TYPES OF LEUKEMIAS WITH THE DIFFERENT LEVELS OF ABL1 PROMOTER METHYLATION. 2001 8 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 9 5274 21 PROMOTER METHYLATION OF P16 AND EDNRB GENE IN LEUKEMIA PATIENTS IN TAIWAN. BOTH EPIGENETIC AND GENETIC ALTERNATIONS ARE INVOLVED IN CANCER FORMATION. IN THIS STUDY, WE HAVE IDENTIFIED THE METHYLATION FREQUENCY OF P16 AND ENDOTHELIN RECEPTOR TYPE B (EDNRB) OF 26 LEUKEMIA PATIENTS AND 8 RANDOMLY SELECTED NORMAL BLOOD DONORS IN TAIWAN. PROMOTER METHYLATION OF P16 WAS DETECTED IN 85% OF ACUTE LYMPHOCYTIC LEUKEMIA (ALL), 83% IN ACUTE MYELOID LEUKEMIA (AML) WHEREAS NO METHYLATION WAS DETECTED IN CHRONIC MYELOID LEUKEMIA (CML) IN BLAST CRISIS. HYPERMETHYLATION OF EDNRB WAS OBSERVED IN 92% OF ALL, 75% AML AND 100% IN CML IN BLAST CRISIS. NO ABERRANT METHYLATION OF P16 AND EDNRB WAS FOUND IN 8 NORMAL BLOOD DONORS. TAKEN TOGETHER, ABERRANT METHYLATION OF P16 AND EDNRB WAS HIGHLY PREVALENT IN LEUKEMIA PATIENTS IN TAIWAN. 2008 10 6793 37 [DOWN-REGULATION OF TRANSCRIPTION FACTOR PU.1 VIA ABNORMAL EPIGENETIC MODIFICATION IN CHRONIC MYELOID LEUKEMIA]. OBJECTIVE: TO INVESTIGATE THE UNDERLYING MECHANISM AND CLINICAL SIGNIFICANCE OF PU.1 DOWN-EXPRESSION IN CHRONIC MYELOID LEUKEMIA (CML) PATIENTS. METHODS: DIFFERENT METHYLATION STATUS OF PU.1 PROMOTER REGION CONTAINING 20 CPG ISLANDS IN NORMAL INDIVIDUALS, CML CHRONIC PHASE AND BLAST CRISIS PATIENTS, COMPLETE CYTOGENETIC REMISSION PATIENTS AFTER IMATINIB TREATMENT, AND BLAST CRISIS BONE MARROW K562 CML CELLS WAS DETECTED BY BISULFITE SEQUENCING. SEMI-QUANTITATIVE PCR WAS USED TO DETECT THE PU.1 MRNA EXPRESSION IN NORMAL CONTROLS, CML CHRONIC PHASE AND BLAST CRISIS PATIENTS, AND BLAST CRISIS BONE MARROW K562 CML CELLS. INDIRECT IMMUNE FLUORESCENCE AND WESTERN BLOT WERE USED TO ANALYZE THE EXPRTESSION OF PU.1 PROTEIN IN NORMAL INDIVIDUALS, CML CHRONIC PHASE AND BLAST CRISIS PATIENTS, AND BLAST CRISIS BONE MARROW K562 CML CELLS. RESULTS: ABERRANT METHYLATION IN THE PROMOTER REGION OF TRANSCRIPTION FACTOR PU.1 WAS FOUND IN BOTH CML CHRONIC PHASE AND BLAST CRISIS PHASE BONE MARROW CELLS, AS WELL AS IN CML BLAST K562 CELLS. DOWN-EXPRESSION OF PU.1 MRNA AND PROTEIN LEVELS WAS FOUND IN ABOVE CELLS. NO METHYLATION IN THE PROMOTER REGION OF PU.1 WAS OBSERVED IN NORMAL INDIVIDUALS, AND THE PU.1 MRNA AND PROTEIN EXPRESSIONS WERE NOT REDUCED AT ALL. FURTHERMORE, HIGH METHYLATION STATUS OF BONE MARROW CELLS WAS EVEN OBSERVED IN THE CML PATIENTS WHO ACQUIRED COMPLETE CYTOGENETIC REMISSION. CONCLUSIONS: THE RESULTS OF OUR STUDY INDICATE THAT THE EPIGENETIC MODIFICATION OF PU.1 IN CML PATIENTS AND K562 CELL LINE MIGHT BE RESPONSIBLE FOR THE DOWN-EXPRESSION OF PU.1. THE DATA SUGGEST THAT ABERRANT METHYLATION OF PU.1 PLAYS A ROLE IN CML PATHOGENESIS, THEREFORE, IT MIGHT SERVE AS A USEFUL BIOMARKER AND POTENTIAL TARGET IN THERAPY FOR CHRONIC MYELOID LEUKEMIA. 2012 11 6780 28 [BLASTIC PLASMACYTOID DENDRITIC CELL NEOPLASM ACCOMPANIED BY CHRONIC MYELOMONOCYTIC LEUKEMIA SUCCESSFULLY TREATED WITH AZACITIDINE]. BLASTIC PLASMACYTOID DENDRITIC CELL NEOPLASM (BPDCN) IS A RARE DISEASE THAT DEVELOPS WITH A SKIN LESION AND IS OFTEN ACCOMPANIED BY LEUKEMIC TRANSFORMATION. THE NORMAL COUNTERPARTS OF BPDCN TUMOR CELLS ARE PROGENITORS OF PLASMACYTOID DENDRITIC CELLS, WHEREAS THE ORIGINS ARE THOUGHT TO BE HEMATOPOIETIC STEM CELLS. APPROXIMATELY 10%-20% OF BPDCN PATIENTS DEVELOP OTHER HEMATOLOGIC MALIGNANCIES, INCLUDING CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). MUTATIONS IN EPIGENETIC REGULATORS ARE FREQUENTLY OBSERVED IN BOTH BPDCN AND CMML TUMORS. AZACITIDINE, A DRUG THAT TARGETS EPIGENETIC DYSREGULATION, IS KNOWN TO BE AN EFFECTIVE TREATMENT FOR CMML. HOWEVER, IT HAS BEEN USED IN FEW BPDCN PATIENTS. HERE, WE REPORT A BPDCN PATIENT WITH SKIN LESIONS, BONE MARROW INFILTRATION, AND LYMPHADENOPATHY. CMML ALSO DEVELOPED DURING THE COURSE OF BPDCN. AZACITIDINE HAD POSITIVE EFFECTS ON CMML; HOWEVER, BPDCN AGGRESSIVELY RELAPSED DURING TREATMENT. TWO TET2 MUTATIONS WERE FOUND IN BOTH BPDCN AND CMML TUMORS; ONE OF WHICH WAS COMMONLY IDENTIFIED IN BOTH TUMORS. 2018 12 571 31 BCR-ABL INDUCES AUTOCRINE IGF-1 SIGNALING. BCR-ABL ONCOGENE IS RESPONSIBLE FOR THE INITIAL PHASE OF CHRONIC MYELOGENOUS LEUKEMIA (CML), WHICH IS EFFECTIVELY TREATED BY THE BCR-ABL INHIBITOR IMATINIB. OVER TIME PATIENTS BECOME RESISTANT TO TREATMENT AND PROGRESS TO BLAST CRISIS, AN EVENT THAT IS DRIVEN BY ADDITIONAL GENETIC AND EPIGENETIC ABERRATIONS. RECENTLY, WE SHOWED THAT RIZ1 EXPRESSION DECREASES IN BLAST CRISIS AND THAT RE-EXPRESSION OF RIZ1 INHIBITS IGF-1 EXPRESSION. IGF-1 SIGNALING IS REQUIRED IN MANY STAGES OF HEMATOPOIESIS AND INAPPROPRIATE ACTIVATION OF AUTOCRINE IGF-1 SIGNALING MAY FACILITATE TRANSFORMATION TO BLAST CRISIS. WE OBSERVED THAT IN 8 OUT OF 11 MATCHED CML PATIENT BIOPSIES THE IGF-1 EXPRESSION IS ELEVATED IN BLAST CRISIS. WE EXAMINED MECHANISMS USED BY CML BLAST CRISIS CELL LINES TO ACTIVATE IGF-1 EXPRESSION. WE FOUND THAT BCR-ABL ACTIVATES AUTOCRINE IGF-1 SIGNALING USING HCK AND STAT5B. INHIBITION OF THESE SIGNALING COMPONENTS USING SMALL MOLECULE DRUGS OR SHRNA DECREASES PROLIFERATION AND ENHANCES APOPTOSIS. TOGETHER, OUR STUDY SUGGESTS THAT ABERRANT IGF-1 SIGNALING IS AN IMPORTANT EVENT IN BLAST CRISIS TRANSFORMATION AND IT PROVIDES A MECHANISM TO EXPLAIN THE ACTIVITY OF IGF-1R AND HCK INHIBITORS IN BLOCKING CML BLAST CRISIS PHENOTYPES. 2008 13 5244 20 PROGNOSTIC INTERACTION BETWEEN ASXL1 AND TET2 MUTATIONS IN CHRONIC MYELOMONOCYTIC LEUKEMIA. MUTATIONS INVOLVING EPIGENETIC REGULATORS (TET2~60% AND ASXL1~40%) AND SPLICING COMPONENTS (SRSF2~50%) ARE FREQUENT IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). ON A 27-GENE TARGETED CAPTURE PANEL PERFORMED ON 175 CMML PATIENTS (66% MALES, MEDIAN AGE 70 YEARS), COMMON MUTATIONS INCLUDED: TET2 46%, ASXL1 47%, SRSF2 45% AND SETBP1 19%. A TOTAL OF 172 (98%) PATIENTS HAD AT LEAST ONE MUTATION, 21 (12%) HAD 2, 24 (14%) HAD 3 AND 30 (17%) HAD >3 MUTATIONS. IN A UNIVARIATE ANALYSIS, THE PRESENCE OF ASXL1 MUTATIONS (P=0.02) AND THE ABSENCE OF TET2 MUTATIONS (P=0.03), ADVERSELY IMPACTED SURVIVAL; WHILE THE NUMBER OF CONCURRENT MUTATIONS HAD NO IMPACT (P=0.3). IN A MULTIVARIABLE ANALYSIS THAT INCLUDED HEMOGLOBIN, PLATELET COUNT, ABSOLUTE MONOCYTE COUNT AND CIRCULATING IMMATURE MYELOID CELLS (MAYO MODEL), THE PRESENCE OF ASXL1 MUTATIONS (P=0.01) AND ABSENCE OF TET2 MUTATIONS (P=0.003) RETAINED PROGNOSTIC SIGNIFICANCE. PATIENTS WERE STRATIFIED INTO FOUR CATEGORIES: ASXL1WT/TET2WT (N=56), ASXL1MUT/TET2WT (N=31), ASXL1MUT/TET2MUT (N=50) AND ASXL1WT/TET2MUT (N=38). SURVIVAL DATA DEMONSTRATED A SIGNIFICANT DIFFERENCE IN FAVOR OF ASXL1WT/TET2MUT (38 MONTHS; P=0.016), COMPARED WITH THOSE WITH ASXL1WT/TET2WT (19 MONTHS), ASXL1MUT/TET2WT (21 MONTHS) AND ASXL1MUT/TET2MUT (16 MONTHS) (P=0.3). WE CONFIRM THE NEGATIVE PROGNOSTIC IMPACT IMPARTED BY ASXL1 MUTATIONS AND SUGGEST A FAVORABLE IMPACT FROM TET2 MUTATIONS IN THE ABSENCE OF ASXL1 MUTATIONS. 2016 14 3871 22 JUVENILE MYELOMONOCYTIC LEUKEMIA - A BONA FIDE RASOPATHY SYNDROME. JUVENILE MYELOMONOCYTIC LEUKEMIA (JMML) IS A PEDIATRIC MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASM OVERLAP SYNDROME WITH SUSTAINED PERIPHERAL BLOOD MONOCYTOSIS, AGGRESSIVE FEATURES, AND POOR OUTCOMES. IN >90% OF CASES JMML IS DRIVEN BY GERMLINE OR SOMATIC MUTATIONS INVOLVING THE CANONICAL RAS PATHWAY (PTPN11, NRAS, CBL, KRAS AND NF1), WITH SOMATIC MUTATIONS/ALTERATIONS IN RAS PATHWAY GENES (SECOND HIT), SETBP1, ASXL1 AND JAK3 RESULTING IN DISEASE PROGRESSION. WHILE SPONTANEOUS REGRESSION HAS BEEN SEEN IN GERMLINE PTPN11 AND CBL MUTANT JMML, IN MOST PATIENTS, ALLOGENEIC STEM CELL TRANSPLANT IS THE ONLY CURATIVE MODALITY. JMML SHARES SEVERAL PHENOTYPIC FEATURES WITH ITS ADULT COUNTERPART PROLIFERATIVE, CHRONIC MYELOMONOCYTIC LEUKEMIA (PCMML). PCMML LARGELY OCCURS DUE TO RAS PATHWAY MUTATIONS THAT OCCUR IN THE CONTEXT OF AGE RELATED CLONAL HEMATOPOIESIS (TET2, SRSF2, ASXL1), WHILE JMML IS A BONA FIDE RASOPATHY, WITH ADDITIONAL SOMATIC MUTATIONS, INCLUDING IN EPIGENETIC REGULATORS GENES RESULTING IN DISEASE PROGRESSION. 2020 15 5980 21 TET2 MUTATIONS WERE PREDICTIVE OF INFERIOR PROGNOSIS IN THE PRESENCE OF ASXL1 MUTATIONS IN PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIA. BACKGROUND: SOMATIC MUTATIONS INVOLVING EPIGENETIC REGULATORS, HISTONE MODIFICATION AND CHROMATIN REGULATION, SPLICING COMPONENTS, TRANSCRIPTION FACTORS AND SIGNALING REGULATOR GENES ARE COMMON IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) PATIENTS. IT HAS BEEN CONSENSUS THAT ASXL1 MUTATIONS HAVE ADVERSELY IMPACT ON OVERALL SURVIVAL (OS), WHILE THE EFFECT OF TET2 MUTATIONS REMAINS CONTROVERSIAL AND UNDEFINED. METHODS: ASXL1 AND TET2 MUTATIONS WERE ANALYZED IN 141 PATIENTS WITH CMML USING SANGER SEQUENCING, WITH THE AIM TO IDENTIFY THE INTERPLAY OF ASXL1 AND TET2 MUTATIONS IN THE PROGNOSIS OF CMML. RESULTS: SIXTY-FIVE (46.1%) OF THE CMML PATIENTS HARBORED ASXL1 MUTATIONS (FRAMESHIFT AND NONSENSE), AND 46 (32.6%) HAD TET2 MUTATIONS (FRAME SHIFT, NONSENSE AND MISSENSE). IN A SEPARATE MULTIVARIABLE ANALYSIS THAT INCLUDED THE MAYO PROGNOSTIC MODEL AS A SINGLE VARIABLE ALONG WITH ASXL1WT/TET2WT, THE RESPECTIVE HAZARD RATIOS OF ASXL1MUT/TET2MUT, ASXL1MUT/TET2WT AND ASXL1WT/TET2MUT WERE 4.7 (95% CI, 2.2-10.3; P<0.001), 2.2 (95% CI, 1.1-4.2; P=0.025) AND 1.3 (95% CI, 0.6-2.5; P=0.521). CONCLUSIONS: OUR STUDY SHOWED THAT ASXL1 MUTATIONS PREDICT INFERIOR OS, AND ADDITIONAL TET2 MUTATIONS WERE ASSOCIATED WITH POOR SURVIVAL IN THE PRESENCE OF ASXL1 MUTATIONS OF CMML PATIENTS. 2016 16 1100 25 COMBINATION OF MYELOPROLIFERATIVE NEOPLASM DRIVER GENE ACTIVATION WITH MUTATIONS OF SPLICE FACTOR OR EPIGENETIC MODIFIER GENES INCREASES RISK OF RAPID BLASTIC PROGRESSION. OBJECTIVES: MYELOPROLIFERATIVE NEOPLASMS (MPN) COMPRISING POLYCYTHEMIA VERA (PV), ESSENTIAL THROMBOCYTHEMIA (ET) AND PRIMARY MYELOFIBROSIS (PMF) FOLLOW A BI-PHASIC COURSE OF DISEASE WITH FIBROTIC AND/OR BLASTIC PROGRESSION. AT PRESENTATION IN THE CHRONIC PHASE, CURRENTLY THERE ARE ONLY INSUFFICIENT TOOLS TO PREDICT THE RISK OF PROGRESSION IN INDIVIDUAL CASES. METHODS: IN THIS STUDY, CHRONIC PHASE MPN (16 PMF, 11 PV, AND 11 MPN UNCLASSIFIED) WITH BLASTIC TRANSFORMATION DURING COURSE OF DISEASE (N = 38, MEDIAN FOLLOW-UP 5.3 YEARS) WERE ANALYZED BY HIGH-THROUGHPUT SEQUENCING. MPN CASES WITH A COMPARABLE FOLLOW-UP PERIOD AND WITHOUT EVIDENCE OF BLAST INCREASE SERVED AS CONTROL (N = 63, MEDIAN FOLLOW-UP 5.8 YEARS). RESULTS: FREQUENT ARCH/CHIP-ASSOCIATED MUTATIONS (TET2, ASXL1, DNMT3A) FOUND AT PRESENTATION WERE NOT SIGNIFICANTLY ASSOCIATED WITH BLASTIC TRANSFORMATION. BY CONTRAST, MUTATIONS OF SRSF2, U2AF1, AND IDH1/2 AT FIRST PRESENTATION WERE FREQUENTLY OBSERVED IN THE PROGRESSION COHORT (13/38, 34.2%) AND WERE COMPLETELY MISSING IN THE CONTROL GROUP WITHOUT BLAST TRANSFORMATION DURING FOLLOW-UP (P = .0007 FOR SRSF2; P = .0063 FOR U2AF1 AND IDH1/2). CONCLUSION: UNLIKE FREQUENT ARCH/CHIP ALTERATIONS (TET2, ASXL1, DNMT3A), MUTATIONS IN SRSF2, IDH1/2, AND U2AF1 WHEN MANIFEST ALREADY AT FIRST PRESENTATION PROVIDE AN INDEPENDENT RISK FACTOR FOR RAPID BLAST TRANSFORMATION OF MPN. 2021 17 3409 38 HOXA4 GENE PROMOTER HYPERMETHYLATION AS AN EPIGENETIC MECHANISM MEDIATING RESISTANCE TO IMATINIB MESYLATE IN CHRONIC MYELOID LEUKEMIA PATIENTS. DEVELOPMENT OF RESISTANCE TO IMATINIB MESYLATE (IM) IN CHRONIC MYELOID LEUKEMIA (CML) PATIENTS HAS EMERGED AS A SIGNIFICANT CLINICAL PROBLEM. THE OBSERVATION THAT INCREASED EPIGENETIC SILENCING OF POTENTIAL TUMOR SUPPRESSOR GENES CORRELATES WITH DISEASE PROGRESSION IN SOME CML PATIENTS TREATED WITH IM SUGGESTS A RELATIONSHIP BETWEEN EPIGENETIC SILENCING AND RESISTANCE DEVELOPMENT. WE HYPOTHESIZE THAT PROMOTER HYPERMETHYLATION OF HOXA4 COULD BE AN EPIGENETIC MECHANISM MEDIATING IM RESISTANCE IN CML PATIENTS. THUS A STUDY WAS UNDERTAKEN TO INVESTIGATE THE PROMOTER HYPERMETHYLATION STATUS OF HOXA4 IN CML PATIENTS ON IM TREATMENT AND TO DETERMINE ITS ROLE IN MEDIATING RESISTANCE TO IM. GENOMIC DNA WAS EXTRACTED FROM PERIPHERAL BLOOD SAMPLES OF 95 CML PATIENTS (38 GOOD RESPONDERS AND 57 RESISTANT) AND 12 NORMAL CONTROLS. ALL SAMPLES WERE BISULFITE TREATED AND ANALYSED BY METHYLATION-SPECIFIC HIGH-RESOLUTION MELT ANALYSIS. COMPARED TO THE GOOD RESPONDERS, THE HOXA4 HYPERMETHYLATION LEVEL WAS SIGNIFICANTLY HIGHER (P = 0.002) IN IM-RESISTANT CML PATIENTS. ON COMPARING THE RISK, HOXA4 HYPERMETHYLATION WAS ASSOCIATED WITH A HIGHER RISK FOR IM RESISTANCE (OR 4.658; 95% CI, 1.673-12.971; P = 0.003). THUS, IT IS REASONABLE TO SUGGEST THAT PROMOTER HYPERMETHYLATION OF HOXA4 GENE COULD BE AN EPIGENETIC MECHANISM MEDIATING IM RESISTANCE IN CML PATIENTS. 2013 18 2719 30 EXOME SEQUENCING REVEALS DNMT3A AND ASXL1 VARIANTS ASSOCIATE WITH PROGRESSION OF CHRONIC MYELOID LEUKEMIA AFTER TYROSINE KINASE INHIBITOR THERAPY. OBJECTIVE: THE DEVELOPMENT OF TYROSINE KINASE INHIBITORS (TKIS) HAS SIGNIFICANTLY IMPROVED THE TREATMENT OF CHRONIC MYELOID LEUKEMIA (CML). HOWEVER, APPROXIMATELY ONE THIRD OF PATIENTS ARE RESISTANT TO TKI AND/OR PROGRESS TO ADVANCED DISEASE STAGES. TKI THERAPY FAILURE HAS A WELL-KNOWN ASSOCIATION WITH ABL1 KINASE DOMAIN (KD) MUTATIONS, BUT ONLY AROUND HALF OF TKI NON-RESPONDERS HAVE DETECTABLE ABL1 KD MUTATIONS. METHOD: WE ATTEMPT TO IDENTIFY GENETIC MARKERS ASSOCIATED WITH TKI THERAPY FAILURE IN 13 PATIENTS (5 RESISTANT, 8 PROGRESSED) WITHOUT ABL1 KD MUTATIONS USING WHOLE-EXOME SEQUENCING. RESULTS: IN 6 PATIENTS, WE DETECTED MUTATIONS IN 6 GENES COMMONLY MUTATED IN OTHER MYELOID NEOPLASMS: ABL1, ASXL1, DNMT3A, IDH1, SETBP1, AND TP63. WE THEN USED TARGETED DEEP SEQUENCING TO VALIDATE OUR FINDING IN AN INDEPENDENT COHORT CONSISTING OF 100 CML PATIENTS WITH VARYING DRUG RESPONSES (74 RESPONSIVE, 18 RESISTANT, AND 8 PROGRESSED PATIENTS). MUTATIONS IN GENES ASSOCIATED WITH EPIGENETIC REGULATIONS SUCH AS DNMT3A AND ASXL1 SEEM TO PLAY AN IMPORTANT ROLE IN THE PATHOGENESIS OF CML PROGRESSION AND TKI-RESISTANCE INDEPENDENT OF ABL1 KD MUTATIONS. CONCLUSION: THIS STUDY SUGGESTS THE INVOLVEMENT OF OTHER SOMATIC MUTATIONS IN THE DEVELOPMENT OF TKI RESISTANT PROGRESSION TO ADVANCED DISEASE STAGES IN CML, PARTICULARLY IN PATIENTS LACKING ABL1 KD MUTATIONS. 2017 19 2848 31 FREQUENT SOMATIC MUTATIONS IN EPIGENETIC REGULATORS IN NEWLY DIAGNOSED CHRONIC MYELOID LEUKEMIA. ALTHOUGH TYROSINE KINASE INHIBITORS (TKIS) HAVE SIGNIFICANTLY IMPROVED THE PROGNOSIS OF CHRONIC MYELOID LEUKEMIA (CML), THE ABILITY OF TKIS TO ERADICATE CML REMAINS UNCERTAIN AND PATIENTS MUST CONTINUE TKI THERAPY FOR INDEFINITE PERIODS. IN THIS STUDY, WE PERFORMED WHOLE-EXOME SEQUENCING TO IDENTIFY SOMATIC MUTATIONS IN 24 PATIENTS WITH NEWLY DIAGNOSED CHRONIC PHASE CML WHO WERE REGISTERED IN THE JALSG CML212 STUDY. WE IDENTIFIED 191 SOMATIC MUTATIONS OTHER THAN THE BCR-ABL1 FUSION GENE (MEDIAN 8, RANGE 1-17). AGE, HEMOGLOBIN CONCENTRATION AND WHITE BLOOD CELL COUNTS WERE CORRELATED WITH THE NUMBER OF MUTATIONS. PATIENTS WITH MUTATIONS ?6 SHOWED HIGHER RATE OF ACHIEVING MAJOR MOLECULAR RESPONSE THAN THOSE<6 (P=0.0381). MUTATIONS IN EPIGENETIC REGULATOR, ASXL1, TET2, TET3, KDM1A AND MSH6 WERE FOUND IN 25% OF PATIENTS. TET2 OR TET3, AKT1 AND RUNX1 WERE MUTATED IN ONE PATIENT EACH. ASXL1 WAS MUTATED WITHIN EXON 12 IN THREE CASES. MUTATED GENES WERE SIGNIFICANTLY ENRICHED WITH CELL SIGNALING AND CELL DIVISION PATHWAYS. FURTHERMORE, DNA COPY NUMBER ANALYSIS SHOWED THAT 2 OF 24 PATIENTS HAD UNIPARENTAL DISOMY OF CHROMOSOME 1P OR 3Q, WHICH DISAPPEARED MAJOR MOLECULAR RESPONSE WAS ACHIEVED. THESE MUTATIONS MAY PLAY SIGNIFICANT ROLES IN CML PATHOGENESIS IN ADDITION TO THE STRONG DRIVER MUTATION BCR-ABL1. 2017 20 4748 33 NOVEL MUTATIONS AND THEIR FUNCTIONAL AND CLINICAL RELEVANCE IN MYELOPROLIFERATIVE NEOPLASMS: JAK2, MPL, TET2, ASXL1, CBL, IDH AND IKZF1. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ORIGINATE FROM GENETICALLY TRANSFORMED HEMATOPOIETIC STEM CELLS THAT RETAIN THE CAPACITY FOR MULTILINEAGE DIFFERENTIATION AND EFFECTIVE MYELOPOIESIS. BEGINNING IN EARLY 2005, A NUMBER OF NOVEL MUTATIONS INVOLVING JANUS KINASE 2 (JAK2), MYELOPROLIFERATIVE LEUKEMIA VIRUS (MPL), TET ONCOGENE FAMILY MEMBER 2 (TET2), ADDITIONAL SEX COMBS-LIKE 1 (ASXL1), CASITAS B-LINEAGE LYMPHOMA PROTO-ONCOGENE (CBL), ISOCITRATE DEHYDROGENASE (IDH) AND IKAROS FAMILY ZINC FINGER 1 (IKZF1) HAVE BEEN DESCRIBED IN BCR-ABL1-NEGATIVE MPNS. HOWEVER, NONE OF THESE MUTATIONS WERE MPN SPECIFIC, DISPLAYED MUTUAL EXCLUSIVITY OR COULD BE TRACED BACK TO A COMMON ANCESTRAL CLONE. JAK2 AND MPL MUTATIONS APPEAR TO EXERT A PHENOTYPE-MODIFYING EFFECT AND ARE DISTINCTLY ASSOCIATED WITH POLYCYTHEMIA VERA, ESSENTIAL THROMBOCYTHEMIA AND PRIMARY MYELOFIBROSIS; THE CORRESPONDING MUTATIONAL FREQUENCIES ARE APPROXIMATELY 99, 55 AND 65% FOR JAK2 AND 0, 3 AND 10% FOR MPL MUTATIONS. THE INCIDENCE OF TET2, ASXL1, CBL, IDH OR IKZF1 MUTATIONS IN THESE DISORDERS RANGES FROM 0 TO 17%; THESE LATTER MUTATIONS ARE MORE COMMON IN CHRONIC (TET2, ASXL1, CBL) OR JUVENILE (CBL) MYELOMONOCYTIC LEUKEMIAS, MASTOCYTOSIS (TET2), MYELODYSPLASTIC SYNDROMES (TET2, ASXL1) AND SECONDARY ACUTE MYELOID LEUKEMIA, INCLUDING BLAST-PHASE MPN (IDH, ASXL1, IKZF1). THE FUNCTIONAL CONSEQUENCES OF MPN-ASSOCIATED MUTATIONS INCLUDE UNREGULATED JAK-STAT (JANUS KINASE/SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION) SIGNALING, EPIGENETIC MODULATION OF TRANSCRIPTION AND ABNORMAL ACCUMULATION OF ONCOPROTEINS. HOWEVER, IT IS NOT CLEAR AS TO WHETHER AND HOW THESE ABNORMALITIES CONTRIBUTE TO DISEASE INITIATION, CLONAL EVOLUTION OR BLASTIC TRANSFORMATION. 2010