Restriction fragment length polymorphisms (RFLP) of the X-chromosome genes phosphoglycerate kinase and hypoxanthine phosphoribosyl transferase were used in conjunction with cytogenetic analysis to study the clonality of hematopoiesis in four female patients with myelodysplastic syndromes, treated with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3), and in one patient with essential thrombocythemia (ET) treated with IL-3.
In a fourth patient with RA and in the patient with ET, treatment with IL-3 resulted in the complete restoration of a non-clonal pattern of peripheral blood cells.
Essential thrombocythemia with the Philadelphia chromosome and BCR-ABL gene rearrangement. An entity distinct from chronic myeloid leukemia and Philadelphia chromosome-negative essential thrombocythemia.
We treated 32 patients with Ph1-negative chronic myeloproliferative disorders (CMD) with excessive thrombocytosis with Interferon alpha-2b (IFN alpha-2b): 26 had essential thrombocythaemia, ET (18 previously untreated, eight pretreated); one thrombocythaemia after treatment for Hodgkin's disease (HD); two thrombocythaemia associated with non-Hodgkin's lymphoma (NHL); three stage II idiopathic myelofibrosis (IM).
We studied 5 patients with essential thrombocythemia utilizing glucose-6-phosphate dehydrogenase (G-6-PD) enzyme as a cell marker for determining clonality.
In order to assess somatic cell mosaicism in various tissues, we have made use of the different rate of utilization of 2-deoxyglucose-6-phosphate, an analog of glucose-6-phosphate, by normal glucose-6-phosphate dehydrogenase and by the Mediterranean variant: the results demonstrate that essential thrombocythemia is a clonal disease involving the erythrocytic, granulocytic, and megakaryocytic series, without affecting monocytes, T lymphocytes, and non-T lymphocytes.
With PCR, we looked for BCR/ABL transcripts in 30 patients with CML and 4 with essential thrombocythaemia at time of diagnosis, finding a significant difference in the platelet counts of CML patients carrying b3a2 or b2a2 transcripts.
We have used this technique to study the clonality of haemopoietic cells in 32 patients with ET and 23 age-matched control heterozygotes for the HUMARA polymorphism.
In comparison with the normal bone marrow and also with P. vera and PTH a significant increase in PCNA-labelling (late G1 and S phases) of megakaryocytes was recognizable in OMF, contrasting with a striking reduction of this marker in CML.
Chromosomal deletions of band 13q14 occur recurrently in BCR/ABL negative chronic myeloproliferative disorders (CMPD), including myelosclerosis with myeloid metaplasia (MMM), polycythemia vera (PV), essential thrombocythemia (ET), juvenile chronic myeloid leukemia (JCML), and the so-called BCR/ABL- chronic myeloid leukemia (CML).
The MPL gene expression was detected in platelets and peripheral blood mononuclear cells from the majority of patients with MPD including chronic myelocytic leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF).
Our results suggest that: (1) p53 gene mutations occur sporadically in the chronic phase of ET, independent of chemotherapy, and may contribute to the progression to the leukaemic phase in a limited number of ET patients; (2) the RAS genes family does not seem to be involved in the pathogenesis of ET, unlike other bcr/abl negative chronic myeloproliferative diseases (CMPDs).
Among 84 consecutive patients with chronic phase Ph-positive chronic myeloid leukemia (CML) who were investigated for the hybrid BCR/ABL mRNA, in six cases (7%) the disease mimicked essential thrombocythemia (ET) at presentation, because of marked thrombocytosis (platelet counts ranging from 1003 x 10(9)/l to 2800 x 10(9)/l) and moderate leukocytosis (WBC counts from 10 x 10(9)/l to 19 x 10(9)/l).
We report results of bcr analysis by Southern hybridization in 37 patients with MPDs other than CML: ET (20 cases), PV (seven cases). unclassified MPD (nine cases), as well as in one case of chronic myelomonocytic leukemia (CMML). bcr negativity ruled out CML in 36 cases, confirming the morphologic diagnosis.In one case diagnosed as ET. bcr gene rearrangement was diagnostic of CML.
These data indicate that inactivation of TP53 is a relatively frequent event associated with the blastic transformation of PV and ET and may be responsible for the tumor progression of these disorders.
Samples of PV and ET analyzed in chronic phase disease were consistently devoid of all genetic lesions tested, suggesting that alterations of TP53, NRAS, KRAS, and MDM2 do not contribute significantly to development of chronic phase PV and ET.
In addition to TP53 mutations, cases of blastic phase PV and ET occasionally harbored mutations of NRAS (one case of blastic phase ET) or displayed MSI (one case of blastic phase PV).
We conclude that it is important to look for BCR-ABL transcript in Ph-neg ET patients and to follow them closely to investigate the nature of this translocation in this group of patients.
A novel myeloid cell line, Marimo, derived from therapy-related acute myeloid leukemia during treatment of essential thrombocythemia: consistent chromosomal abnormalities and temporary C-MYC gene amplification.
The results of our study together with a review of literature data suggest that different BCR/ABL transcript variants may occur in CML mimicking ET, without an apparently significant prevalence of one type.