Sylwia Czekalska

The Gain-of-Function JAK2 V617F Mutation Shifts the Phenotype of Essential Thrombocythemia and Chronic Idiopathic Myelofibrosis to More “Erythremic” and Less “Thrombocythemic”: A Molecular, Histologic, and Clinical Study

We investigated the prevalence of the JAK2 V617F gain-of-function mutation in patients with Philadelphia chromosome-negative chronic myeloproliferative disorders (Ph- MPD) and explored the links between JAK2 mutational status and the clinicopathologic picture of essential thrombocythemia (ET), chronic idiopathic myelofibrosis (CIMF), and polycythemia vera (PV). Allele-specific polymerase chain reaction results for 59 ET, 18 CIMF, and 9 PV cases were compared with values for clinical variables at presentation and last follow-up and with the diagnostic trephine bone marrow biopsy pictures. JAK2 V617F was found in 38 (64%) of ET cases, 7 (39%) of CIMF cases, and 9 (100%) of PV cases. The ET patients with the mutant JAK2 showed significantly higher (although not overtly polycythemic) red blood cell parameter values, lower platelet counts, and higher white blood cell counts. Similar trends were found in CIMF. Megakaryocyte clustering was much less pronounced in the CIMF cases with mutant JAK2, with an analogous trend occurring in the ET cases. Bone marrow cellularity values and the numbers of CD34+ and CD117+ blasts in the ET and CIMF groups did not differ. Fibrosis was slightly less marked in the ET cases with mutant JAK2. The mutation did not significantly influence the clinical course during the follow-up in either disease in the short term (median follow-up, 22 months). The JAK2 V617F mutation is prevalent in all Ph- MPD and may skew their presenting phenotype, including bone marrow histology, toward a more “erythremic” and less “thrombocythemic” phenotype.

Cladribine added to daunorubicin-cytarabine induction prolongs survival of FLT3-ITD+ normal karyotype AML patients.

To the editor: Internal tandem duplication in the FLT3 gene ( FLT3- ITD) has been recognized as a marker conferring poor outcome in patients with normal karyotype acute myeloid leukemia (NK-AML).[1][1] Because of the inferior outcome of FLT3- ITD+ NK-AML patients when treated with standard

The JAK2 V617F mutation in Philadelphia-negative chronic myeloproliferative disorders

Buccal epithelial cells are occasionally used as a source of supposedly non-neoplastic DNA in patients suffering from haematological malignancies. Formerly, Kralovics et al found the JAK2 V617F mutation in DNA derived from buccal swabs in only 2.2% of patients with Philadelphia-negative chronic myeloproliferative disorders (Ph− CMPD).1 We compared the JAK2 V617F mutational status in DNA derived from buccal swabs to that in DNA extracted from either bone marrow or peripheral blood in 35 Ph− CMPD patients, including five cases of polycythaemia vera (PV), five cases of chronic idiopathic myelofibrosis (CIMF) and 25 cases of essential thrombocythaemia (ET). Genomic DNA was isolated from buccal swabs immediately on collection and …

CEBPA copy number variations in normal karyotype acute myeloid leukemia: Possible role of breakpoint-associated microhomology and chromatin status in CEBPA mutagenesis

Copy number variations (CNV) in CEBPA locus represent heterogeneous group of mutations accompanying acute myeloid leukemia (AML). The aim of this study was to characterize different CEBPA mutation categories in regard to biological data like age, cytology, CD7, and molecular markers, and identify possible factors affecting their etiology. We report here the incidence of 12.6% of CEBPA mutants in the population of 262 normal karyotype AML (NK-AML) patients. We confirmed that double mutant AMLs presented uniform biological features when compared to single CEBPA mutations and accompanied mostly younger patients. We hypothesized that pathogenesis of distinct CEBPA mutation categories might be influenced by different factors. The detailed sequence analysis revealed frequent breakpoint-associated microhomologies of 2 to 12bp. The analysis of distribution of microhomology motifs along CEBPA gene showed that longer stretches of microhomology at the mutational junctions were relatively rare by chance which suggests their functional role in the CEBPA mutagenesis. Additionally, accurate quantification of CEBPA transcript levels showed that double CEBPA mutations correlated with high-level CEBPA expression, whereas single N-terminal CEBPA mutations were associated with low-level CEBPA expression. This might suggest that high-level CEBPA expression and/or accessibility of CEBPA locus contribute to B-ZIP in-frame duplications.

Monitorowanie kinetyki zmian wczesnego chimeryzmu hematopoetycznego i charakterystyka wszczepienia molekularnego za pomocą metody STR-PCR u pacjentów poddanych alloHSCT☆☆☆

Streszczenie Allogeniczna transplantacja komorek hematopoetycznych jest jednym ze sposobow leczenia nowotworowych i nienowotworowych schorzen hematologicznych. Po przeszczepieniu komorki hematopoetyczne dawcy osiedlają sie w niszach szpikowych biorcy, co skutkuje powstaniem prawidlowego ukladu krwiotworczego i immunologicznego o genotypie dawcy - calkowity chimeryzm dawcy. Wszczepienie molekularne (ME) poprzedza wystąpienie wszczepienia hematologicznego. Wczesna ocena chimeryzmu moze miec istotne znaczenie dla dalszego przebiegu procesu przyjmowania sie przeszczepienia i warunkuje mozliwośc podjecia wczesnej interwencji leczniczej. Do badania wlączono 38 pacjentow, u ktorych wykonano 43 allogeniczne transplantacje (alloHSCT). Przyjmowanie sie przeszczepu śledzono we krwi obwodowej od 2. do 14. doby po transplantacji, nastepnie w 21. i 28. dobie. W 30. dobie poziom chimeryzmu oznaczano we krwi obwodowej i w szpiku kostnym. Chimeryzm hematopoetyczny oceniano przy zastosowaniu metody molekularnej STR-PCR. Wykazano, ze zmiany poziomu chimeryzmu we wczesnym okresie po transplantacji w grupie pacjentow poddanych alloSCT (alloHSCT po-przedzona kondycjonowaniem mieloablacyjnym) przebiegają zgodnie z zaleznością liniową (R2=0,996), natomiast w grupie pacjentow poddanych alloNMSCT (alloHSCT poprzedzona kondycjonowaniem niemie-loablacyjnym) są zgodne z zaleznością logarytmiczną (R2=0,959). Poziom chimeryzmu hematopoetycznego jest wyzszy w grupie pacjentow poddanych alloSCT, w 2. dobie roznice te cechuje znamiennośc statystyczna (p=0,0048). Wszczepienie molekularne poprzedza wystąpienie wszczepienia hematologicznego (pacjenci poddani alloSCT p=1,44×10−12, pacjenci pod-dani alloNMSCT p=2,12×10−6). W grupach pacjentow poddanych alloSCT i alloHSCT, ktorzy otrzymali wiecej niz 3×106 komorek CD34+/kg masy data roznica w czasie wystąpienia ME w porownaniu z grupą chorych, ktorzy otrzymali mniej niz 3×106 komorek CD34+/kg, byla znamienna statystycznie (alloSCT p=0,0013, alloHSCT p = 0,021).

Clonal lymphocytic populations in Philadelphia-negative chronic myeloproliferative disorders: is the T-cell clonality of ‘undetermined’ significance (TCUS) linked to a worse clinical outcome?

This study examined the clonality of B- and T-cells by PCR in 83 patients with Philadelphia-negative myeloproliferative disorders (Ph-MPD), to investigate its clinical and morphological correlates. Clonal lymphocytic populations were found in 23% of patients (T: n = 20, B: n = 3), with no frequency differences between ET, CIMF and PV. At the presentation, patients with clonal bands were older (58.1±13.8 vs 47.5±14.6, p = 0.0039), but did not differ in other clinical parameters. After the median follow-up of 21 months they were less likely to be asymptomatic (11.8% vs 41.1%, p = 0.029). The T-cell clonality was the strongest predictor of the symptomatic last follow-up by discriminant function analysis, surpassing the patients age. This surprising negative prognostic impact of lymphocyte clonality in Ph-MPD may result from this phenomenon to be a better measure of the ‘hematopoietic biologic age’ than the metrical age itself.