Contributions
Abstract: PB2268
Type: Publication Only
Background
Primary myelofibrosis (PMF) is a BCR-ABL1-negative myeloproliferative neoplasm (MPN). PMF has the most heterogeneous clinical course among MPNs and is characterized by increased proliferation of megakaryocytes, progressive bone marrow fibrosis, extramodullary hematopoiesis, leukoerythroblastosis and shortened survival.
Mutations in primary myelofibrosis (PMF) are operationally classified into 2 categories: drivers (JAK2, MPL, CALR) and others. Mutations in JAK2 and MPL genes lead to constitutive activation of JAK2/STAT signaling pathway that results in increased proliferation of myeloid and magakaryocytic progenitors in absence of TPO and EPO. CALR gene encodes calreticulin, a protein which plays role in intracellular signaling, Ca2+ storage, regulation of gene expression, cell adhesion, apoptosis and autoimmune response. Mutations of these three genes are reciprocally exclusive. “Triple negative” PMF cases with any of them are associated with poor prognosis. Driver mutations might be accompanied by other mutations whose pathogenetic relevance is even less clear (ASXL1, SRSF2, IDH1/2, EZH2, TET2, DNMT3A, and CBL). SRSF2 spliceosome mutations play a crucial role during RNA splicing pathway. Hotspot mutations in the exon 2 have been identified in PMF (3-17%).
Aims
The aim of the study was to evaluate and relate mutational status of JAK2, MPL, CALR genes and splicing factor SRSF2 in Polish group of PMF patients and find associations between mutated and nonmutated cases.
Methods
JAK2V617F and MPLW515K/L mutation status were assessed using AS-PCR. Direct sequencing was performed to detect insertion/deletion of exon 9 of CALR gene and mutations of exon 2 of SRSF2 gene. Relationship between the presence or absence (“triple negative”) of these mutations and hematological and clinical data of patients was analyzed with Mann Whitney U Test.
Results
Out of the 98 patients, 36 (37%) carried JAK2V617F, 25 (26%) CALR exon 9 indel, 12 (13%) mutation of exon 2 SRSF2 gene, 3 (3%) MPLW515 mutation and 22 (21%) were “triple negative”. Among the three MPL-mutated cases 2 samples exhibited splice factor gene mutations SRSF2 (66%). JAK2/V617F was accompanied by SRSF2 mutation in 4 cases (11%), while CALR was rarely combined with splice factor gene mutations (4%). We found significant correlation (0,005) between high plateled (PLT) count and the presence of any mutation (median 207,5) in comparison to PLT in patients without mutation (median 74). An analogical association was detected between patients CALR(+) mutation (median PLT 333), and CALR(-) mutation (102,5), p=0,018. We have not found any significant relationship between clinical parameters and the presence of analyzed mutations.
Conclusion
Obtained result may suggest a clinical importance of simultaneous analysis of driver and spliceosome mutations, like SRSF2.
Session topic: 15. Myeloproliferative neoplasms – Biology & Translational Research
Keyword(s): Mutation status, Myelofibrosis
Abstract: PB2268
Type: Publication Only
Background
Primary myelofibrosis (PMF) is a BCR-ABL1-negative myeloproliferative neoplasm (MPN). PMF has the most heterogeneous clinical course among MPNs and is characterized by increased proliferation of megakaryocytes, progressive bone marrow fibrosis, extramodullary hematopoiesis, leukoerythroblastosis and shortened survival.
Mutations in primary myelofibrosis (PMF) are operationally classified into 2 categories: drivers (JAK2, MPL, CALR) and others. Mutations in JAK2 and MPL genes lead to constitutive activation of JAK2/STAT signaling pathway that results in increased proliferation of myeloid and magakaryocytic progenitors in absence of TPO and EPO. CALR gene encodes calreticulin, a protein which plays role in intracellular signaling, Ca2+ storage, regulation of gene expression, cell adhesion, apoptosis and autoimmune response. Mutations of these three genes are reciprocally exclusive. “Triple negative” PMF cases with any of them are associated with poor prognosis. Driver mutations might be accompanied by other mutations whose pathogenetic relevance is even less clear (ASXL1, SRSF2, IDH1/2, EZH2, TET2, DNMT3A, and CBL). SRSF2 spliceosome mutations play a crucial role during RNA splicing pathway. Hotspot mutations in the exon 2 have been identified in PMF (3-17%).
Aims
The aim of the study was to evaluate and relate mutational status of JAK2, MPL, CALR genes and splicing factor SRSF2 in Polish group of PMF patients and find associations between mutated and nonmutated cases.
Methods
JAK2V617F and MPLW515K/L mutation status were assessed using AS-PCR. Direct sequencing was performed to detect insertion/deletion of exon 9 of CALR gene and mutations of exon 2 of SRSF2 gene. Relationship between the presence or absence (“triple negative”) of these mutations and hematological and clinical data of patients was analyzed with Mann Whitney U Test.
Results
Out of the 98 patients, 36 (37%) carried JAK2V617F, 25 (26%) CALR exon 9 indel, 12 (13%) mutation of exon 2 SRSF2 gene, 3 (3%) MPLW515 mutation and 22 (21%) were “triple negative”. Among the three MPL-mutated cases 2 samples exhibited splice factor gene mutations SRSF2 (66%). JAK2/V617F was accompanied by SRSF2 mutation in 4 cases (11%), while CALR was rarely combined with splice factor gene mutations (4%). We found significant correlation (0,005) between high plateled (PLT) count and the presence of any mutation (median 207,5) in comparison to PLT in patients without mutation (median 74). An analogical association was detected between patients CALR(+) mutation (median PLT 333), and CALR(-) mutation (102,5), p=0,018. We have not found any significant relationship between clinical parameters and the presence of analyzed mutations.
Conclusion
Obtained result may suggest a clinical importance of simultaneous analysis of driver and spliceosome mutations, like SRSF2.
Session topic: 15. Myeloproliferative neoplasms – Biology & Translational Research
Keyword(s): Mutation status, Myelofibrosis