Novel Variant of the SLC4A1 Gene Associated with Hereditary Spherocytosis.

Hereditary spherocytosis (HS) refers to the group of the most frequently occurring non-immune hereditary hemolytic anemia in people of Caucasian central or northern European ancestry. HS is mainly associated with pathogenic variants of genes encoding defects in five membrane proteins, including anion exchanger 1 encoded by the SLC4A1 gene. In this study, in a family affected with HS, we identified a hitherto unreported AE1 defect, variant p.G720W. The result of it is most likely the HS phenotype. Molecular dynamics simulation study of the AE1 transmembrane domain may indicate reasonable changes in AE1 domain structure, i.e., significant displacement of the tryptophan residue towards the membrane surface connected with possible changes in AE1 function. The WES analysis verified by classical sequencing in conjunction with biochemical analysis and molecular simulation studies shed light on the molecular mechanism underlying this case of hereditary spherocytosis, for which the newly discovered AE1 variant p.G720W seems crucial.

A rare mutation (p.F149del) of the NT5C3A gene is associated with pyrimidine 5'-nucleotidase deficiency.

Pyrimidine 5'-nucleotidase deficiency is a rare erythrocyte enzymopathy. Here we report two cases of hemolytic anemia in brothers of Polish origin that are associated with a very rare mutation. Heterozygous deletion in the NT5C3A gene (c.444_446delGTT), inherited most likely from their asymptomatic mother, resulted in a single amino acid residue deletion (p.F149del) in cytosolic pyrimidine 5'-nucleotidase. However, only the mutated transcript was present in the reticulocyte transcriptome of both patients. Only residual activity of pyrimidine 5'-nucleotidase in the brothers' erythrocytes could be observed when compared with the controls, including their asymptomatic father and sister. Western blot showed no sign of the presence of 5'-nucleotidase protein in the erythrocytes of both studied patients. The 2.5-fold reduction of the purine/pyrimidine ratio observed only in the brothers' erythrocytes confirms the correlation of the results of molecular analysis, including whole-exome sequencing, with the phenotype of the pyrimidine 5'-nucleotidase deficiency. Altogether, our results may substantiate the hypothesis of the heterogeneity of the molecular basis of the defect involving both the mutation presented here and negative regulation of expression of the "normal" allele.

COVID-19 therapies: do we see substantial progress?

The appearance of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its spread all over the world is the cause of the coronavirus disease 2019 (COVID-19) pandemic, which has recently resulted in almost 400 million confirmed cases and 6 million deaths, not to mention unknown long-term or persistent side effects in convalescent individuals. In this short review, we discuss approaches to treat COVID-19 that are based on current knowledge of the mechanisms of viral cell receptor recognition, virus-host membrane fusion, and inhibition of viral RNA and viral assembly. Despite enormous progress in antiviral therapy and prevention, new effective therapies are still in great demand.

Identification of a Novel Mutation of ß-Spectrin in Hereditary Spherocytosis Using Whole Exome Sequencing.

Hereditary spherocytosis (HS), the most commonly inherited hemolytic anemia in northern Europeans, comprises a group of diseases whose heterogeneous genetic basis results in a variable clinical presentation. High-throughput genome sequencing methods have made a leading contribution to the recent progress in research on and diagnostics of inherited diseases and inspired us to apply whole exome sequencing (WES) to identify potential mutations in HS. The data presented here reveal a novel mutation probably responsible for HS in a single Polish family. Patients with clinical evidence of HS (clinical symptoms, hematological data, and EMA test) were enrolled in the study. The examination of the resulting WES data showed a number of polymorphisms in 71 genes associated with known erythrocyte pathologies (including membranopathies, enzymopathies, and hemoglobinopathies). Only a single SPTB gene variant indicated the possible molecular mechanism of the disease in the studied family. The new missense mutation p.C183Y was identified using WES in the SPTB gene, which is most likely the cause of clinical symptoms typical of hereditary spherocytosis (membranopathy) due to structural and functional impairments of human ß-spectrin. This mutation allows for a better understanding of the molecular mechanism(s) of one of the membranopathies, hereditary spherocytosis.

IDH2 mutations in patients with normal karyotype AML predict favorable responses to daunorubicin, cytarabine and cladribine regimen.

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) genes occur in about 20% patients with acute myeloid leukemia (AML), leading to DNA hypermethylation and epigenetic deregulation. We assessed the prognostic significance of IDH1/2 mutations (IDH1/2+) in 398 AML patients with normal karyotype (NK-AML), treated with daunorubicine + cytarabine (DA), DA + cladribine (DAC), or DA + fludarabine. IDH2 mutation was an independent favorable prognostic factor for 4-year overall survival (OS) in total NK-AML population (p = 0.03, censoring at allotransplant). We next evaluated the effect of addition of cladribine to induction regimen on the patients' outcome according to IDH1/2 mutation status. In DAC group, 4-year OS was increased in IDH2+ patients, compared to IDH-wild type group (54% vs 33%; p = 0.0087, censoring at allotransplant), while no difference was observed for DA-treated subjects. In multivariate analysis, DAC independently improved the survival of IDH2+ patients (HR = 0.6 [0.37-0.93]; p = 0.024; censored at transplant), indicating that this group specifically benefits from cladribine-containing therapy. In AML cells with R140Q or R172K IDH2 mutations, cladribine restrained mutations-related DNA hypermethylation. Altogether, DAC regimen produces better outcomes in IDH2+ NK-AML patients than DA, and this likely results from the hypomethylating activity of cladribine. Our observations warrant further investigations of induction protocols combining cladribine with IDH1/2 inhibitors in IDH2-mutant.

Comparing radioactive tracers 18F-FDG and 18F-FLT in the staging of diffuse large B-cell lymphoma by PET/CT examination: A single-center prospective study.

BACKGROUND: Positron emission tomography in combination with computer tomography (PET/CT) is a very important method of imaging patients with non-Hodgkin lymphomas (NHLs). It is used to define the initial grade of the disease and to assess early response to treatment and after chemotherapy. The most commonly used radioactive tracer is 18F-FDG, but 18F-FLT seems to be more specific. OBJECTIVES: The aim of our study was to compare the staging of diffuse large B-cell lymphoma (DLBCL) with PET/CT examination using 18F-FLT and 18F-FDG. MATERIAL AND METHODS: The study included 33 patients with newly diagnosed DLBCL (17 women and 16 men). The median age of the patients was 57 years. In each patient, 2 PET/CT examinations were performed before treatment, one using 18F-FLT and the second using 18F-FDG. RESULTS: The average maximum 18F-FDG uptake in the whole group of patients was higher than the average maximum of 18F-FLT. This was also true of individual patients; however, 3 patients with an aggressive disease course had greater FLT uptake than the other patients. CONCLUSIONS: Our analysis suggests that PET/CT exams using 18F-FLT may be a useful diagnostic tool in patients with DLBCL.

Significance of apoptosis and autophagy of leukemic blasts for the outcomes of acute myeloid leukemia patients.

BACKGROUND: Cytostatic treatment induces apoptosis or other types of cell death like autophagy, necrosis, mitotic catastrophe, etc. Autophagy can play a role in the drug resistance of neoplastic cells, allowing the survival of blast cells under stressful conditions, such as the use of cytostatics. Studies on apoptosis and autophagy 12-24 h after the start of treatment have not been conducted until now. OBJECTIVES: The study aimed to investigate the predictive and prognostic significance of autophagy and apoptosis in patients with acute myeloid leukemia (AML). MATERIAL AND METHODS: The study included 38 patients. Blood was collected before and 12-24 h after the start of treatment, since at that time point, the appropriate blast cell count was still available. Autophagy was measured with the expression of the ATG5, MAP1L3, LC3-I, and LC3-II proteins. The percentage of mononuclear cells in early and late apoptosis was evaluated with flow cytometry, using the annexin V and propidium iodide (PI) binding assay. RESULTS: The percentage of apoptotic blast cells before treatment was not associated with the response. However, in the remission group, the overall percentage of apoptotic cells measured 12-24 h after the start of treatment was higher than in non-remission patients, which was statistically significant. In neither group we found any difference in the level of autophagy before and 12-24 h after the start of treatment. Nevertheless, we observed an increasing tendency of the MAP1LC3 protein expression (not statistically significant) in the remission group 12-24 h after the start of treatment. Patients with a higher percentage of blast cells in apoptosis and with a higher expression of MAP1LC3 protein measured 12-24 h after the start of the therapy had longer overall survival (OS). CONCLUSIONS: A higher percentage of apoptotic as well as autophagic blast cells measured 12-24 h after the start of the chemotherapy is an independent factor associated with better outcomes.

Influence of temperature rise by 2.5°C on the increase of apoptosis of HL-60 cells treated with busulfan.

BACKGROUND: Hyperthermia is one of the new and still poorly known methods used in cancer treatment. It consists of raising the patient's body temperature for therapeutic purposes. The article presents the results of in vitro studies describing the effect of an elevated temperature of 39.5°C, the busulfan cytostatic and their combination on the level of apoptosis of human leukemia HL-60 cells. OBJECTIVES: During the experiments, the influence of a 2.5°C temperature increase on the behavior of the population of 2 groups of HL-60 cells, with busulfan cytostatic and without the cytostatic, was investigated. The control group consisted of 2 groups of HL-60 cells incubated at 37.0°C with the cytostatic and without the cytostatic. Two questions were asked: 1. Is low-temperature hyperthermia likely to have an effect on the effectiveness of busulfan cytostatic? 2. Does the increase in temperature by 2.5°C have an effect on the level of apoptosis in the unsaturated HL-60 cell line? MATERIAL AND METHODS: Human promyelocytic leukemia cell line HL-60 was used in the experiments to examine the influence of temperature on apoptosis HL-60 in 2 separated incubators set to 37.0°C and 39.5°C for 3 h. Apoptosis was assessed with flow cytometry using Annexin V. RESULTS: An increase in mortality of HL-60 cells was found in the case of simultaneous exposure to elevated temperature and busulfan in comparison to the group of cells treated with the cytostatic alone. There was no observed effect of an elevated temperature of 39.5°C alone on the level of HL-60 cell apoptosis. CONCLUSIONS: Analysis of the study results indicates that low-temperature hyperthermia may be used to increase the effectiveness of busulfan treatment. No effect of an elevated temperature of 39.5°C on the level of apoptosis in HL-60 cells that were not treated with busulfan was observed. There is a need to test the efficacy of other cytostatic agents at elevated temperatures.

G-CSF administration favours SDF-1 release and activation of neutrophils and monocytes in recipients of autologous peripheral blood progenitor cells.

G-CSF is a growth factor widely used to mobilise CD34+ progenitor cells for clinical applications. The present study aimed to assess expression of G-CSF receptor (CSF3R) on neutrophils and monocytes, as well as SDF-1 and G-CSF serum levels in relation to efficacy of G-CSF-induced mobilisation for autologous transplantation. For this purpose, 105 patients with haematological disorders and 46 healthy controls were investigated. Before mobilisation patients were characterised with significantly higher percentage of CSF3R expressing neutrophils (p < 0.001) and monocytes (p = 0.002), than controls. G-CSF administration resulted in a decrease of CSF3R+ neutrophils (p < 0.001) and monocytes (p < 0.001), while presence of G-CSF receptor on neutrophils tended to negatively affect mobilisation yield (p = 0.075). G-CSF concentration increased during mobilisation (p < 0.001). On the 5th day of mobilisation a positive correlation was observed between G-CSF and SDF-1 serum levels (p < 0.001) and the number of CD34+ cells released from bone marrow seemed to be related to both G-CSF (p = 0.036) and SDF-1 levels (p = 0.084). As compared to Hodgkin's lymphoma patients, those with multiple myeloma had lower basal percentage of CSF3R+ neutrophils (p = 0.014) while Non-Hodgkin's lymphoma cases exhibited higher G-CSF (p = 0.026) and SDF-1 (p = 0.006) concentration on mobilisation day 5. Hodgkin's lymphoma patients were also characterised with worse mobilisation efficacy than multiple myeloma (p = 0.022) and Non-Hodgkin's lymphoma (p = 0.013) patients. These results suggest that both SDF-1 and G-CSF play a role in HSC release into peripheral blood and show that G-CSF administration affects expression of CSF3R on monocytes and neutrophils, implying potential role of these cell subpopulations in mobilisation process.

Efficient method for isolation of reticulocyte RNA from healthy individuals and hemolytic anaemia patients.

Despite enormous progress and development of high-throughput methods in genome-wide mRNA analyses, data on the erythroid transcriptome are still limited, even though they could be useful in medical diagnostics and personalized therapy as well as in research on normal and pathological erythroid maturation. Although obtaining normal and pathological reticulocyte transcriptome profiles should contribute greatly to our understanding of the molecular bases of terminal erythroid differentiation as well as the mechanisms of the hematological diseases, a basic limitation of these studies is the difficulty of efficient reticulocyte RNA isolation from human peripheral blood. The restricted number of possible parallel experiments primarily concern healthy individuals with the lowest number of reticulocytes in the peripheral blood and a low RNA content. In the present study, an efficient method for reticulocyte RNA isolation from healthy individuals and hemolytic anaemia patients is presented. The procedure includes leukofiltration, Ficoll-Paque gradient centrifugation, Percoll gradient centrifugation, and negative (CD45 and CD61) immunomagnetic separation. This relatively fast and simple four-stage method was successfully applied to obtain a reticulocyte-rich population from healthy subjects, which was used to efficiently isolate the high-quality RNA essential for successful NGS-based transcriptome analysis.

Evaluation of the impact of treatment with hematopoietic stem cells transplantation (HSCT) on biochemical markers of heart function and novel electrocardiographic markers of repolarization in patients with hematological malignancies.

High-dose chemotherapy (HDC) followed by stem cell transplantation (HSCT) is a well-established method in patients with hematological malignancies, and for last few years, many efforts have been made to estimate short- and long-term efficacy of this method, as well as early and late complications. The present study concentrates on cardiotoxic effects, mainly early changes using biochemical markers such as N-terminal natriuretic peptide type B (NT-proBNP) and cardiac troponins (cTn). Simultaneously, the analysis of 12-lead ECG was done before and after the procedure in which the novel repolarization markers: Tp-e and Tp-e/QT ratio were measured, together with standard markers: QT, QTc. It was found that NT-pro BNP was significantly increased after HSCT in comparison to results before it, and no significant changes were present in Troponin levels. Simultaneously, Tp-e interval and Tp-e/QT ratio were significantly higher after HSCT. The use of cyclophosphamide, advanced age, and higher level of blood cholesterol concentration were risk factors for the increase in NT-proBNP and treatment with cyclophosphamide as well as fludarabine and higher creatinine levels were risk factors for the increase in Tp-e/QT ratio. In conclusion, in the early term evaluation after HSCT in patients with no previously diagnosed heart disease, the mild changes in markers of heart overload and repolarization were noted. The observations suggest that in all patients undergoing HSCT, even the ones without pre-existing cardiovascular disease, the evaluation, and monitoring of heart function should be considered.

Constitutional mutations of the CHEK2 gene are a risk factor for MDS, but not for de novo AML.

CHEK2 plays a key role in cellular response to DNA damage, and also in regulation of mitosis and maintenance of chromosomal stability. In patients newly diagnosed with myelodysplastic syndrome (MDS, n = 107) or acute myeloid leukemia (AML, n = 117) congenital CHEK2 mutations (c.444 + 1G > A, c.1100delC, del5395, p.I157 T) were tested by PCR and sequencing analysis. The karyotype of bone marrow cells of each patient was assessed at disease diagnosis using classical cytogenetic methods and fluorescence in situ hybridization. The CHEK2 mutations were strongly associated with the risk of MDS (p < 0.0001) but not with the risk of de novo AML (p = 0.798). In CHEK2-positive MDS patients, two times higher frequency of aberrant karyotypes than in CHEK2-negative patients was found (71% vs. 37%, p = 0.015). In CHEK2-positive patients with cytogenetic abnormalities, subtypes of MDS: refractory anemia with excess blasts-1 or 2, associated with unfavorable disease prognosis, were diagnosed two times more often than in CHEK2-negative cases with aberrations (78% vs. 44%). In conclusion, the congenital CHEK2 inactivation is strongly associated with the risk of MDS and with a poorer prognosis of the disease. However, the chromosomal instability in AML is not correlated with the hereditary dysfunction of CHEK2.

HLA-inferred extended haplotype disparity level is more relevant than the level of HLA mismatch alone for the patients survival and GvHD in T cell-replate hematopoietic stem cell transplantation from unrelated donor.

Serious risks in unrelated hematopoietic stem cell transplantation (HSCT) including graft versus host disease (GvHD) and mortality are associated with HLA disparity between donor and recipient. The increased risks might be dependent on disparity in not-routinely-tested multiple polymorphisms in genetically dense MHC region, being organized in combinations of two extended MHC haplotypes (Ehp). We assessed the clinical role of donor-recipient Ehp disparity levels in N = 889 patients by the population-based detection of HLA allele phase mismatch. We found increased GvHD incidences and mortality rates with increasing Ehp mismatch level even with the same HLA mismatch level. In multivariate analysis HLA mismatch levels were excluded from models and Ehp disparity level remained independent prognostic factor for high grade acute GvHD (p = 0.000037, HR = 10.68, 95%CI 5.50-32.5) and extended chronic GvHD (p < 0.000001, HR = 15.51, CI95% 5.36-44.8). In group with single HLA mismatch, patients with double Ehp disparity had worse 5-year overall survival (45% vs. 56%, p = 0.00065, HR = 4.05, CI95% 1.69-9.71) and non-relapse mortality (40% vs. 31%, p = 0.00037, HR = 5.63, CI95% 2.04-15.5) than patients with single Ehp disparity. We conclude that Ehp-linked factors contribute to the high morbidity and mortality in recipients given HLA-mismatched unrelated transplant and Ehp matching should be considered in clinical HSCT.

The role of hypoxia-inducible factors in leukemias.

Hypoxia, understood as low partial oxygen pressure, has become one of the most explored fields in recent years. Cellular response to hypoxia is mediated by hypoxia-inducible factors (HIFs) - potent transcription regulators, and their downstream pathways. In general, HIFs modify energy metabolism, inflammation and immune response, enhance cancer invasion, metastasis, resistance to treatment, and relapse. The influence of HIFs on the progression of leukemia is still under investigation in various studies, but in mice and some human models HIFs have been recognized as leukemia immortalizers by promoting leukemic stem cell quiescence and inhibiting their cell cycle. This makes leukemic stem cells resistant to most known treatment approaches. The role of HIFs in solid tumors and leukemia makes them almost ideal targets for an anticancer treatment. Although the first attempts with new molecules are encouraging, there is a need to investigate the ambiguous role of HIFs to develop a modern antileukemic treatment.

Genetic variation of the gene coding for microRNA-204 (miR-204) is a risk factor in acute myeloid leukaemia.

BACKGROUND: MicroRNAs (miRNAs or miRs) are small molecules known to be involved in post-transcriptional gene expression. Many of them have been shown to influence risk for various diseases. Recent studies suggest that lower expression of miR-204, a gene coding for miRNA-204, is correlated with shorter survival in patients with acute myeloid leukaemia (AML). This observation prompted us to analyse the effect of two polymorphisms of the miR-204 gene, one in the upstream flanking region (rs718447 A > G) and the other inside the gene itself (rs112062096 A > G), both also in intron 3 of the TRPM3 gene. METHODS: The study was conducted on DNA samples isolated from AML patients (n = 95) and healthy individuals (n = 148), who were genotyped using the Light SNiP assays. RESULTS: The miR-204 rs718447 GG homozygosity was found to constitute a risk factor associated with susceptibility to AML (73/95 vs 92/148, AML patients vs healthy controls, OR = 2.020, p = 0.017). Additionally, this genotype was more frequent in patients with subtypes M0-M1 in the French-American-British (FAB) classification as compared to patients with subtypes M2-M7 (23/25 vs 39/57, p = 0.026). We also found that presence of allele A was linked to longer survival of AML patients. CONCLUSIONS: Our results show that polymorphism in miR-204 flanking region may constitute a risk and prognostic factor in AML.

The analysis of the parameters of 24-hr ECG Holter monitoring in patients with blood neoplasms undergoing high-dose chemotherapy and stem cell transplantation.

BACKGROUND: Hematopoietic stem cell transplantation (HSCT) is a widely used procedure in the treatment of malignant diseases, including blood neoplasms and has increased survival in hematological diseases. The aim of the study was to analyze parameters of 24-hr ECG monitoring in patients with selected blood neoplasms in whom the procedure of hematopoietic stem cell transplantation was performed. METHODS: The study group consisted of 64 adults diagnosed with hematologic cancer qualified for HSCT with the previous high dose chemotherapy (HDC). In all patients 24-hr Holter monitoring was carried out twice. First examination took place prior to the HSCT procedure, and the second after finishing the procedure of HSCT. RESULTS: The minimal and mean heart rate (HR min and HR max) from 24-hr ECG recording was statistically significantly higher after the transplantation in comparison with the first test. The number of premature ventricular complexes (PVCs) was higher in the test after HSCT. In the second examination there was significantly higher percentage of premature ventricular complexes, incidents of tachycardia, and Mobitz type 1 second degree atrioventricular block. In regression analysis, in a group of patients with blood neoplasms after HSCT and HDC, administration of cyclophosphamide, fludarabine and total body irradiation were independent risk factors for electrocardiographic abnormalities in 24-hr Holter monitoring, that is, the increase in HR min, HR mean and PVCs. CONCLUSION: In patients with blood neoplasms undergoing HSCT more electrocardiographic abnormalities may be found after this procedure in comparison with the 24-hr Holter monitoring before transplantation.

Bone marrow adipocytes in haematological malignancies.

Bone marrow adipocytes (BMAs) derived from mesenchymal stem cells (MSC) are an active and significant element of the bone marrow microenvironment. They are involved in metabolic functions, complex interactions with other stromal cells, and in the development and progression of tumours. Currently, there is little data regarding the role of BMAs in haematological malignancies. Due to this, we have attempted to characterise the BMAs in these malignancies in terms of quantity and morphology. Our study included 30 patients aged 22-76 with myelo- (n=17) and lymphoproliferative malignancies (n=13), both with and without bone marrow infiltration. Trepanobioptate was the evaluated material. The number and diameter of BMAs were measured, and the percentage of adipocytes (adipocyte fraction - AF), hematopoietic cells (hematopoietic fraction - HF) and trabecular bone (trabecular bone fraction - BF) was calculated. The obtained results were considered against the clinical parameters of age, sex, body weight, body surface area (BSA) and body mass index (BMI). We observed that as age increases, the number of BMA/mm2, the diameter of adipocytes and AF increase while BF and HF decrease. However, this relationship was not statistically significant. A significant correlation of BMA parameters was also not found in relation to weight, BMI and BSA, and the number and diameter of BMAs were comparable in both sexes. The trepanobioptate of infiltrated bone marrow showed a decreased number of BMA/mm2 compared to the trepanobioptate from bone marrow without infiltration (97.44±69.16 vs. 164.14±54.16; p=0.010) with a marked difference in men (69.75±65.26 vs. 180.33±60.40; p=0.007). These trepanobioptate also showed an increase in the number of BMA/mm2 with age (r=0.472; p=0.041), and with an increase of BMI, an increase in diameter of BMAs (r=0.625; p=0.007) and AF (r=0.546; p=0.023). The number and size of BMAs, as well as AF, BF and HF in patients with myeloproliferative malignancies did not differ significantly compared to patients with lymphoproliferative malignancies.

MRP1 protein expression in leukemic stem cells as a negative prognostic marker in acute myeloid leukemia patients.

BACKGROUND: It is well established that expression of multi-drug resistance (MDR) proteins (MDR1, BCRP, MDR3, MRP1, and LRP) in leukemic blasts correlates with acute myeloid leukemia (AML) patients' clinical response. Assuming that leukemic stem cells (LSC) are resistant to chemotherapy and responsible for relapse, it might be clinically relevant to evaluate the expression level of MDR proteins in LSC and relate it to the clinical outcome. METHODS: Bone marrow samples from 26 patients with de novo AML were labeled with antibodies to distinguish CD34+CD38-CD123+ LSC population and with antibodies against MDR1, BCRP, MDR3, MRP1, or LRP proteins. Multicolor flow cytometry was applied to evaluate the expression of MDR proteins in blasts and LSC. RESULTS: Nine of 26 patients with AML attained CR (30%). High negative correlation was found between MDR1 and LRP expression in blasts and the patient's remission. MDR proteins were expressed more frequently in LSC than in leukemic blasts. High negative correlation was also observed between remission achievement and MRP1 expression in LSC. CONCLUSIONS: Our data present for the very first time the high negative correlation between MRP1 protein expression in LSC and AML patients' remission. It does strongly suggest that MRP1 expression in LSC is an adverse prognostic marker in patients with de novo AML.