Cytogenetic studies in 174 consecutive patients with preleukemic or myelodysplastic syndromes

Mouse Models of Myeloid Malignancies

Mouse models of human myeloid malignancies support the detailed and focused investigation of selected driver mutations and represent powerful tools in the study of these diseases. Carefully developed murine models can closely recapitulate human myeloid malignancies in vivo, enabling the interrogation of a number of aspects of these diseases including their preclinical course, interactions with the microenvironment, effects of pharmacological agents, and the role of non-cell-autonomous factors, as well as the synergy between co-occurring mutations. Importantly, advances in gene-editing technologies, particularly CRISPR-Cas9, have opened new avenues for the development and study of genetically modified mice and also enable the direct modification of mouse and human hematopoietic cells. In this review we provide a concise overview of some of the important mouse models that have advanced our understanding of myeloid leukemogenesis with an emphasis on models relevant to clonal hematopoiesis, myelodysplastic syndromes, and acute myeloid leukemia with a normal karyotype.

Isolated +15 in bone marrow: disease-associated or a benign finding?

It has been controversial if trisomy 15 (+15) as an isolated clonal cytogenetic abnormality in bone marrow (BM) is disease-associated or a benign finding. To answer this question, we retrospectively reviewed our cytogenetic archives and identified 31 patients with isolated +15. Four patients presented with acute myeloid leukemia (AML), +15 was the major clone (56-95% of interphases) in BM and the clonal size of +15 was correlated with blast burden and disease status. For the remaining 27 patients, +15 was a minor clone (3-24% of interphases) in BM. Eighteen patients had a history of cytotoxic therapies and developed +15 after a median latency interval of 34 months. Six patients had BM involvement by lymphoma or myeloma, and +15 was exclusively detected in myeloid and erythroid cells, not in lymphoma or myeloma cells. With a median follow-up of 28 months, none of these 27 patients had clinical or morphological evidence of myelodysplastic syndromes. We conclude that +15 can be associated with AML, but more often isolated +15 presents as a minor clone in BM, and may not be disease associated. Clinical follow-up rather than an immediate therapeutic intervention seems most appropriate for non-leukemic patients with isolated +15.

Morphology, cytogenetics and classification of MDS

Myelodysplastic syndromes are heterogeneous bone marrow diseases with a variable pathogenetic background. Cytomorphological alterations in peripheral blood films as well as bone marrow aspirates and histological findings in trephine biopsies result from cytogenetic and molecular abnormalities, epigenetic dysregulation and immune dysfunction and are key elements for setting the diagnosis of MDS. Whereas diagnosis can be made quite easily in advanced MDS this is much more difficult in early MDS, especially in cases with cytopenias or dysplasias of uncertain significance (ICUS and IDUS). Recommendations, illustrated by case reports for a stepwise annealing to the final diagnosis and exclusion of differential diagnoses are given. Furthermore, the problem of correct counting and identification of blasts is covered and features defining dysplasia in all three cell lineages are recapitulated thoroughly. Histopathology is not mandatory but has a distinct diagnostic and prognostic value especially in cases with hypoplasia or fibrosis and when the TP53 mutational status is of relevance. In up to 70% of patients with MDS clonal chromosome abnormalities can be identified which have a high impact on setting the correct diagnosis and estimation of prognosis. Incidence, type, molecular background and clinical relevance of distinct anomalies as well as cytogenetic subgroups are presented in detail and the development of the new cytogenetic prognostic scoring system as part of the IPSS-R is explained. The value of FISH-Analysis as a complementary tool for chromosome analysis in MDS is demonstrated with special emphasis on the possibility to perform frequent cytogenetic monitoring by CD34-FISH examination of peripheral blood. Finally the evolution of MDS-classification systems from FAB to WHO with a critical discussion of their shortcomings like degree of dysplasia, blast thresholds, inclusion/exclusion of CMML, and the lack of dynamic information is presented.

Will a peripheral blood (PB) sample yield the same diagnostic and prognostic cytogenetic data as the concomitant bone marrow (BM) in myelodysplasia?

In patients with myelodysplastic syndromes (MDS), chromosome anomalies are detected by conventional cytogenetic studies (CCS) and/or interphase fluorescence in situ hybridization (FISH) of bone marrow (BM) samples and provide prognostic and diagnostic information, which can direct therapy. Whether peripheral blood (PB) can be substituted for bone marrow in these cases and can provide the same information remains unknown. Concurrent BM and PB specimens collected from 100 patients with recently diagnosed MDS were studied using both CCS and FISH. While 68% of BM samples showed an abnormal karyotype by CCS, only 31% of PB samples were abnormal by CCS. In 12% of patients, FISH and CCS were discordant due to the inability of the FISH panel to detect all possible abnormalities. However, only one case (1%) had a cryptic abnormality detected by FISH. BM and PB FISH were discordant in 3% of cases, most likely due to the smaller clone size in PB vs. BM. While PB should not be substituted for BM at diagnosis, it is a viable alternative for monitoring patients using the appropriate FISH probe(s).

New comprehensive cytogenetic scoring system for primary myelodysplastic syndromes (MDS) and oligoblastic acute myeloid leukemia after MDS derived from an international database merge

PURPOSE

The karyotype is a strong independent prognostic factor in myelodysplastic syndromes (MDS). Since the implementation of the International Prognostic Scoring System (IPSS) in 1997, knowledge concerning the prognostic impact of abnormalities has increased substantially. The present study proposes a new and comprehensive cytogenetic scoring system based on an international data collection of 2,902 patients.

PATIENTS AND METHODS

Patients were included from the German-Austrian MDS Study Group (n = 1,193), the International MDS Risk Analysis Workshop (n = 816), the Spanish Hematological Cytogenetics Working Group (n = 849), and the International Working Group on MDS Cytogenetics (n = 44) databases. Patients with primary MDS and oligoblastic acute myeloid leukemia (AML) after MDS treated with supportive care only were evaluated for overall survival (OS) and AML evolution. Internal validation by bootstrap analysis and external validation in an independent patient cohort were performed to confirm the results.

RESULTS

In total, 19 cytogenetic categories were defined, providing clear prognostic classification in 91% of all patients. The abnormalities were classified into five prognostic subgroups (P < .001): very good (median OS, 61 months; hazard ratio [HR], 0.5; n = 81); good (49 months; HR, 1.0 [reference category]; n = 1,809); intermediate (26 months; HR, 1.6; n = 529); poor (16 months; HR, 2.6; n = 148); and very poor (6 months; HR, 4.2; n = 187). The internal and external validations confirmed the results of the score.

CONCLUSION

In conclusion, these data should contribute to the ongoing efforts to update the IPSS by refining the cytogenetic risk categories.

Impacts of cytogenetic categories in the Revised International Prognostic Scoring System on the prognosis of primary myelodysplastic syndromes: results of a single-center study

Recently, the Revised International Prognostic Scoring System (IPSS-R) has been developed for assessing the prognosis of primary myelodysplastic syndromes (MDS) and has shown satisfactory outcomes for prognostic stratification. In this new system, cytogenetics remains the key stratification parameter and karyotypic abnormalities are classified into five prognostic subgroups with more uncommon cytogenetic subsets. Using this system, we analyzed the cytogenetic features of 532 adult Chinese patients with primary MDS and assessed the impacts of the IPSS-R cytogenetic categories on the prognosis of the disease without intensive treatment. Here, we show that the cytogenetic features of this cohort of Chinese patients are different from those of previously reported Western populations with MDS. In our Chinese patients, trisomy 8 was the most common anomaly, and the incidence rate of del(5q) was lower than that in the Western population. In the IPSS-R cytogenetic subgroups, the median survival was 59 months for the good risk, 36 months for the intermediate risk, 15 months for the poor risk and 10 months for the very poor risk subgroups (p < 0.001). In conclusion, the IPSS-R can effectively stratify the prognosis of MDS based on cytogenetics, but the prognostic significances of some karyotypes in the IPSS-R still need to be confirmed by larger multicenter cooperative studies.

Evolution Of Clonal Cytogenetic Abnormalities in Aplastic Anemia

Prior to the introduction of effective therapies, the high mortality rates of severe aplastic anemia (AA) precluded recognition of late complications of this disease. Once the survival of AA improved, observation of clonal evolution raised questions as to whether the development of secondary myelodysplastic syndrome (MDS) is a part of the extended natural history of the disease or is related to the therapies applied. Clinical features of myelodysplasia and AA can overlap, and typical MDS may evolve as a complication of AA. Common pathophysiologic elements operate in these diseases and are subject to many studies and theories as to what mechanisms in AA may lead to the late evolution of MDS. Similarly, AA has been hypothesized to be a reflection of an over-reactive immune response triggered by the appearance of genetically altered and/or phenotypically abnormal dysplastic clones. Hypocellular variants of myelodysplasia and responsiveness of certain forms of MDS to immunosuppressive regimens serve as the most appealing examples of the intricate and close pathophysiologic relationship of this disease with AA. The diagnosis of clonal evolution in the course of AA can be obvious if secondary cytopenia involves hypercellularity and a high percentage of blasts. In addition, the occurrence of a new karyotypic defect objectively heralds the progression of disease to MDS. However, the diagnostic imprecision of dysplasia recognition in the context of marrow hypocellularity, inability to obtain informative cytogenetics, and a high proportion of MDS cases with normal karyoptype have hampered studies designed to determine the frequency and timing of MDS evolution in AA. In addition, the diagnostic criteria and definitions used are not unified. While some centers recognize that the abnormal karyotype does not preclude the diagnosis of AA; in others, the diagnosis of AA includes the presence of normal karyoptype. Many typical features of dysplastic evolution in AA have been clarified. For example, karyotypes most frequently encountered in MDS secondary to AA involve chromosomes 6, 7 and 8. The evolution rates seem to be in the range of 10-15% in 10 years, but there are no predictive clues as to which patients are at greatest risk for this complication. Study of the mechanisms of clonal evolution in AA may help understand the pathophysiology of other forms of MDS and leukemia and also the mechanisms of antileukemic surveillance. Clinically, identification of patients at increased risk for clonal complications may influence the choice of therapies applied.

Cytogenetic features in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) comprise a group of bone marrow diseases characterized by profound heterogeneity in morphologic presentation, clinical course, and cytogenetic features. Roughly 50% of patients display clonal chromosome abnormalities. In several multicentric studies, the karyotype turned out to be one of the most important prognostic parameters and was incorporated into statistical models aiming for a better prediction of the individual prognosis like the International Prognostic Scoring System. However, due to the profound cytogenetic heterogeneity, the impact of many rare abnormalities as well as combinations of anomalies occurring in a substantial portion of patients with MDS is still unknown and can only be delineated on the basis of large international multicentric cooperations. Recently, the German-Austrian MDS Study Group presented cytogenetic findings in 2,072 patients with MDS, which serve as a basis for the characterization of the cytogenetic subgroups discussed in this article. The availability of new therapeutic options for low- and high-risk MDS targeted against distinct entities characterized by specific chromosome abnormalities, like 5q-deletions, monosomy 7, and complex abnormalities underlines the important role of cytogenetics for the clinical management of MDS. This article thus focuses on the clinical and prognostic relevance, the molecular background, and therapeutic perspectives in these three cytogenetic subgroups.

Evaluation of chromosome 5 aberrations in complex karyotypes of patients with myeloid disorders reveals their contribution to dicentric and tricentric chromosomes, resulting in the loss of critical 5q regions

Dicentric chromosomes have often been observed in complex karyotypes in previously reported studies of therapy-related myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Fluorescence in situ hybridization (FISH) has now made the characterization of these rearrangements much easier. Dicentric and tricentric chromosomes were identified in 21 patients (9 MDS and 12 AML) among the 133 consecutive MDS/AML patients (17%) who had a structural or numerical aberration of chromosome 5 using conventional cytogenetic analysis. One third (7/21) of the patients had received alkylating drugs for a previously diagnosed cancer or chronic myeloproliferative disease. Loss of 5q material was identified in all 21 patients. One copy of the EGR1 (5q31) or the CSF1R (5q33 approximately q34) genes was lost in 20 of the 21 patients. Dicentric and tricentric chromosomes involving chromosome 5 are frequently observed in complex karyotypes among patients with de novo or therapy-related MDS/AML. They lead to deletions of various parts of the long arm of chromosome 5.

Clinical implications of SOCS1 methylation in myelodysplastic syndrome

The suppressor of cytokine signalling-1 (SOCS1) protein is a tumour suppressor. Hypermethylation of SOCS1 gene, resulting in transcriptional silencing, is suggested to play an important role in cancer development. We sought to characterise SOCS1 methylation in primary myelodysplastic syndrome (MDS) and clarify its clinical implications. The methylation status of SOCS1 was analysed by methylation-specific polymerase chain reaction in 114 patients with primary MDS and serial studies were performed in 29 of them. SOCS1 methylation occurred in 54 patients (47.4%), and was more frequent in patients with high-risk MDS than in those with low-risk (52.6% vs. 25.8%, P = 0.011). SOCS1 methylation was closely associated with NRAS mutation (P = 0.010) and inversely associated with good-risk karyotype (P = 0.021). With a median follow-up of 17 months (range: 1-231 months), two patients acquired SOCS1 methylation during disease progression. In two patients, SOCS1 methylation present at diagnosis, disappeared after haematopoietic stem cell transplantation. Patients with SOCS1 methylation had a higher cumulative risk of leukaemic transformation than those without (55.8% vs. 27.7% at 3 years, P = 0.004). This difference remained significant within the subgroup of patients with high-risk MDS (67.3% vs. 45.1% at 3 years, P = 0.045). This is the first report to demonstrate the clinical relevance of SOCS1 methylation in MDS. It may play an important role in the pathogenesis of MDS, especially among patients with high-risk subtypes.

Myelodysplastic syndromes with isolated deletion of the long arm of the chromosome X as a sole cytogenetic change

Deletions of Xq are extremely rare events in myelodysplastic syndromes (MDS) patients and were previously described in five patients, in two of them as a sole chromosome abnormality. We found isolated del(Xq) in 3 of 127 MDS patients with clonal chromosome changes. Detailed analysis of clinical and morphological data of presented and previously published cases indicates the following: (1) del(X)(q24) and del(X)(q13) are nonrandom chromosomal abnormalities in MDS; (2) MDS with deletions of Xq affect exclusively females ages 46-65; and (3) deletions of Xq are associated with refractory anemia with excess blasts (RAEB) and indicate an unfavorable prognosis.

Clinical and molecular cytogenetic studies in seven patients with myeloid diseases characterized by i(20q−)

We report on seven patients with myeloid diseases characterized by i(20q-) anomaly. Four patients were male and three were female, their median age was 57 years. The diagnosis at presentation was myelodysplastic syndrome in six patients, acute myeloid leukaemia in one patient. Four died but three survived and remain anaemic. The survivals were 6 months for patient 1, 7 months for patient 2, 17 d for patient 4 and 28 d for patient 5. Chromosome specimens were prepared by direct and/or short-term culture of bone marrow cells. Karyotype analysis was performed by R- and G-banding technique, which showed that one of the normal chromosomes 20 was substituted by one or two small metacentric chromosomes in all seven patients. The karyotype was ider(20)(q10)del(20)(q11q13), i.e. i(20q-) in six patients by dual-colour fluorescence in situ hybridization assay using two probes (a subtelomeric probe for 20q and an unique probe for 20q12). As far as we know, this anomaly has not been reported previously. Thus, we consider that i(20q-) is a novel and rare recurrent chromosomal abnormality that is specifically associated with myeloid diseases and may indicate a poor prognosis.

Protein 4.1 deficiency and deletion of chromosome 20q are associated with acquired elliptocytosis in myelodysplastic syndrome

We report a case of myelodysplastic syndrome (MDS), associated with prominent elliptocytosis. A 66-year-old male presented with peripheral pancytopenia, and was diagnosed with MDS [refractory anaemia (RA)]. Apart from marked elliptocytosis, dyshaematopoietic features were not evident in his peripheral blood or hypercellular bone marrow. After 18 months, he had progressed to RA with excess blasts in transformation. Analysis of red blood cell membrane proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a reduced quantity of protein 4.1 (30% of control). Deletion of chromosome 20q was identified by conventional cytogenetic analysis and fluorescence in situ hybridization. Marked elliptocytosis, persistent for more than 17 months, decreased strikingly after chemotherapy with idarubicin and Ara-C. These findings suggest that acquired elliptocytosis occurred as an unusual morphological feature of MDS, associated with abnormalities of protein 4.1 and chromosome 20q.

Trisomy 15 as the sole abnormality in myelodysplastic syndromes: case report and review of the literature

Trisomy 15 as the sole autosomal anomaly is uncommon in hematological malignancies but could be preferentially associated with myelodysplasia. We report a 61-year-old man who developed pancytopenia following two courses of chemotherapy for chronic lymphoid leukemia. Cytogenetic studies at diagnosis of pancytopenia with R banding showed a 47,XY, + 15[3]/45,X[3]/46,XY[14] karyotype. A review of the 53 cases of myelodysplastic syndromes (MDS) and myeloid related disorders associated with trisomy 15 reported in the literature showed that 18 of the 31 men also lost the Y chromosome in the trisomic 15 cell line. Their mean age was significantly higher than that of males who had not lost the Y chromosome (p < 0.05). The main feature of the patient reported here is the presence of two abnormal cell lines, one having lost the Y chromosome, the other having gained a chromosome 15. Therefore, the two events occurred independently, the loss of the Y chromosome being possibly due to aging and the trisomy 15 to the hematologic disorder.

Cytogenetic and FISH studies in myelodysplasia, acute myeloid leukemia, chronic lymphocytic leukemia and lymphoma

Conventional cytogenetic studies are widely used today to diagnose and manage patients with hematological malignancies. The application of fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes helps to further define molecular subclasses and cytogenetic risk categories for patients with these disorders. Moreover, FISH permits analysis of proliferating (metaphase cells) and non-proliferating (interphase nuclei) cells, and is useful in establishing the percentage of neoplastic cells before and after therapy (minimal residual disease). For patients with myelodysplasia or acute myeloid leukemia, these chromosome techniques are important for accurate diagnosis and classification of disease and to help decide treatment and monitor response to therapy. Conventional cytogenetic studies have been problematic in chronic lymphocytic leukemia because the neoplastic cells divide infrequently. However, interphase FISH studies now permit detection of chromosome anomalies with prognostic significance in chronic lymphocytic leukemia. The World Health Organization recognizes that genetic anomalies are one of the most reliable criteria for classification of malignant lymphomas. New methods to extract individual nuclei from paraffin-embedded tissue are now available which permit the use of interphase FISH to detect important chromosome anomalies in lymphoma.

Distinct clinical outcomes for cytogenetic abnormalities evolving from aplastic anemia

A serious complication of aplastic anemia (AA) is its evolution to clonal hematologic diseases such as myelodysplasia (MDS) and leukemia, which is usually associated with the appearance of a cytogenetic abnormality in bone marrow cells. We present here an analysis of a cohort of 30 patients with otherwise typical AA in whom clonal karyotypic evolution was observed during frequent periodic marrow examinations. The actuarial risk for this complication has been estimated in other studies at around 15% at 5 years. Conversion from normal to abnormal karyotype occurred at a constant rate after initial diagnosis, with about 50% of cases developing within the first 30 months. Transient chromosomal abnormalities were infrequent. Clinically, AA patients with clonal cytogenetic patterns were heterogenous; a variety of karyotypic defects with numerical and structural abnormalities of chromosome 7 accounted for 40% of all cases followed by trisomy 8, structural and numerical abnormalities of chromosome 13, deletion of Y chromosome, and complex cytogenetic abnormalities. Unlike in primary MDS, aberrancies of chromosome 5 and 20 were infrequent. The clinical course depended on the specific abnormal cytogenetic pattern. Most deaths related to leukemic transformation occurred in patients with abnormalities of chromosome 7 or complex cytogenetic alterations or both. Evolution of chromosome 7 abnormalities was seen most often in refractory patients who had failed to respond to therapy. In contrast, trisomy 8 developed in patients with good hematologic responses who often required chronic immunosuppression with cyclosporine A (CsA), and survival was excellent. Although AA patients with monosomy 7 showed a similar prognosis to those with primary MDS, trisomy 8 in AA appears to have a more favorable prognosis than in MDS.

Extramedullary myeloid cell tumours localised to the mediastinum: a rare clinicopathological entity with unique karyotypic features

Extramedullary myeloid cell tumour (EMMT) localised to the mediastinum is a rare manifestation of acute myeloid leukaemia, forming less than 4% of all cases of EMMT. In contrast to other types of EMMT, cytogenetic characteristics of this rare entity are relatively unknown. This report describes a patient with EMMT who had evidence of superior vena cava syndrome and normal peripheral blood counts at diagnosis. The results from an initial biopsy specimen were consistent with a diagnosis of mediastinal large B cell lymphoma. A diagnosis of acute myeloid leukaemia was made three months after initial diagnosis by bone marrow examination. Review of the initial biopsy specimen showed strong positivity for myeloperoxidase, revealing that the patient had been initially misdiagnosed as having large B cell lymphoma. Cytogenetic studies revealed a near triploid and near tetraploid karyotype with structural abnormalities in 12 and three metaphases, respectively. Review of the literature showed that a near tetraploid or triploid karyotype is found in most of the reported cases of mediastinal EMMT. Thus, the presence of a near triploid/tetraploid karyotype and mediastinal EMMT may represent a specific subset of EMMT. The biological relevance of this observation is discussed.

Deletion of 16q11 is a recurrent cytogenetic aberration in acute myeloblastic leukemia during disease progression

Abnormalities of chromosome 16 other than inv(16)(p13q22), t(16;16)(p13;q22), and del(16)(q22) have not been fully characterized in acute myeloblastic leukemia (AML) and myelodysplastic syndrome (MDS). We report here the first case of AML with del(16)(q11) as a sole abnormality. A 53-year-old woman was initially diagnosed as MDS, refractory anemia with excess of blasts in transformation with normal karyotype. After sixteen months, the disease progressed to overt AML-M1. Myeloblasts were positive for CD13, CD33, and CD34, but negative for HLA-DR. Chromosome analyses of the bone marrow cells showed 46,XX,del(16)(q11) in all metaphase spreads. Multicolor spectral karyotyping also confirmed that del(16)(q11) was not derived from a cryptic translocation, but a simple deletion. Our results, together with three previously reported cases, suggest that del(16)(q11) may be one of the recurrent aberrations in AML and that it could be associated with clonal evolution or disease progression.

Chromosome and molecular abnormalities in myelodysplastic syndromes

Cytogenetic abnormalities are seen in approximately 50% of cases of myelodysplastic syndrome (MDS) and 80% of cases of secondary MDS (following chemotherapy or radiotherapy). These abnormalities generally consist of partial or complete chromosome deletion or addition (del5q, -7, +8, -Y, del20q), whereas balanced or unbalanced translocations are rarely found in MDS. Fluorescence hybridization techniques (fluorescence in situ hybridization [FISH], multiplex FISH, and spectral karyotyping) are useful in detecting chromosomal anomalies in cases in which few mitoses are obtained or rearrangements are complex. Ras mutations are the molecular abnormalities most frequently found in MDS, followed by p15 gene hypermethylation, FLT3 duplications, and p53 mutations, but none of these abnormalities are specific for MDS. The rare cases of balanced translocations in MDS have allowed the identification of genes whose rearrangements appear to play a role in the pathogenesis of some cases of MDS. These genes include MDS1-EVI1 in t(3;3) or t(3;21) translocations, TEL in t(5;12), HIP1 in t(5;7), MLF1 in t(3;5), and MEL1 in t(1;3). Genes more frequently implicated in the pathogenesis of MDS cases, such as those involving del5q, remain unknown, although some candidate genes are currently being studied. Cytogenetic and known molecular abnormalities generally carry a poor prognosis in MDS and can be incorporated into prognostic scoring systems such as the International Prognostic Scoring System.

Methylation of the p15(INK4B) gene in myelodysplastic syndrome: it can be detected early at diagnosis or during disease progression and is highly associated with leukaemic transformation

To investigate the time sequence of occurrence of p15(INK4B) gene methylation in myelodysplastic syndrome (MDS) and its correlation with leukaemic transformation and survival of patients, the methylation status of the p15(INK4B) promoter region was analysed in 50 patients and was serially studied in 22 of them. Of the 50 patients, 17 (34%) showed p15(INK4B) gene methylation, first demonstrated at diagnosis or during follow-up. When FAB subtypes at the time of study were used in the analysis, the incidence of (p15INK4B) methylation in each risk group of MDS remained stable throughout the course: 0% for low-risk MDS [refractory anaemia (RA) and RA with ring sideroblasts] and from 23% at diagnosis to 30% for high-risk MDS [RA with excess of blasts (RAEB), RAEB in transformation and chronic myelomonocytic leukaemia] respectively. The incidence of p15(INK4B) methylation rose to 60% at initial study and, finally, to 75% in cases of acute myeloid leukaemia (AML) evolved from MDS. Most patients (69%) with p15(INK4B) methylation showed disease progression to AML; it could be detected before, at the time or after the diagnosis of leukaemic transformation. p15(INK4B) methylation in MDS patients implicated a shorter survival time in univariate analyses, but its prognostic significance disappeared in multivariate analyses. In conclusion, p15(INK4B) methylation can be detected early at the diagnosis of MDS or acquired during disease progression. It may play an important role in the pathogenesis of some high-risk MDS and is related to leukaemic transformation of MDS.

Deletion of Xq23 is a recurrent karyotypic abnormality in acute myeloid leukemia

Deletion of chromosome Xq23 has been reported in a number of solid tumors, including soft tissue sarcoma, malignant melanoma, astrocytoma, and adenocarcinoma. The deleted Xq often occurs in a setting of very complex karyotypic changes. A similar abnormality has also been described in rare cases of acute myeloid leukemia (AML) but in no other hematologic malignancies. In this study, we report the occurrence of del(X)(q23) in two cases of AML.

Trisomy 15, sex chromosome loss, and hematological malignancy

We report 6 patients with myelodysplasia who, on routine cytogenetic studies, demonstrated trisomy 15. Four of these also had sex chromosome loss. A review of the literature revealed 6 other cases of trisomy 15 with sex chromosome loss and 22 cases of trisomy 15 as the sole chromosomal abnormality. All cases had hematologic malignancy or myelodysplasia. Trisomy 15 is uncommon but tends to be associated with myelodysplasia in older subjects, and with sex chromosome loss in about one third of cases.

Incidence, characterization and prognostic significance of chromosomal abnormalities in 640 patients with primary myelodysplastic syndromes. Grupo Cooperativo Español de Citogenética Hematológica

Recently, a consensus International Prognostic Scoring System (IPSS) for predicting outcome and planning therapy in the myelodysplastic syndromes (MDS) has been developed. However, the intermediate-risk cytogenetic subgroup defined by the IPSS includes a miscellaneous number of different single abnormalities for which real prognosis at present is uncertain. The main aims of this study were to evaluate in an independent series the prognostic value of the IPSS and to identify chromosomal abnormalities with a previously unrecognized good or poor prognosis in 640 patients. In univariate analyses, cases with single 1q abnormalities experienced poor survival, whereas those with trisomy 8 had a higher risk of acute leukaemic transformation than the remaining patients (P = 0.004 and P = 0.009 respectively). Patients with single del(12p) had a similar survival to patients with a normal karyotype and showed some trend for a better survival than other cases belonging to the IPSS intermediate-risk cytogenetic subgroup (P = 0.045). Multivariate analyses demonstrated that IPSS cytogenetic prognostic subgroup, proportion of bone marrow blasts and haemoglobin level were the main prognostic factors for survival, and the first two characteristics and platelet count were the best predictors of acute leukaemic transformation risk. A large international co-operative study should be carried out to clarify these findings.

Treatment of unfavorable myelodysplastic syndrome with all-trans-retinoic acid and subcutaneous Ara C

Thirty patients with high-risk myelodysplastic syndrome, defined as > 5% bone marrow blasts, were treated with a combination of oral all-trans-retinoic acid (45 mg/m2 daily) and subcutaneous AraC (10 mg/m2) on days 1-14 of each 28-35 day cycle repeated for 2-6 cycles. Complete remission lasting 9, 12, and 15 months was achieved in three patients. Partial and minor response did not translate into meaningful clinical improvement, like complete responders. Overall incidence of leukemia transformation and survival of this cohort of patients was no different from the expected outcome for a group of patients with similar characteristics.

Chromosomal instability in acute myelocytic leukemia and myelodysplastic syndrome patients among atomic bomb survivors

To clarify the mechanism of leukemogenesis in atomic bomb survivors, leukemic cells were investigated using fluorescence in situ hybridization (FISH) analysis on the basis of conventional G-banding in patients with a history of radiation exposure and also in de novo patients. Conventional G-banding showed higher incidences (p < 0.005) of structural and numerical abnormalities without any specific types of chromosome aberrations in the group exposed to a dose of more than one Gy, compared to the non-exposed group. FISH analysis revealed significantly higher incidences (P < 0.05) of subclones with monosomy 7 and deletion of the 20q13.2 region, which were not found in conventional cytogenetic analysis in the exposed group (more than one Gy) compared to the non-exposed controls. Furthermore, segmental jumping translocation (SJT) of the c-MYC gene region was observed only in the exposed group. These chromosomal instability suggested that the leukemic cells from the heavily exposed patients contained persistent cellular genetic instability which may strongly influence the development of leukemia in people exposed to radiation.

A single-center population-based consecutive series of 1500 cytogenetically investigated adult hematological malignancies: karyotypic features in relation to morphology, age and gender

During the 18-yr period 1976-93, a population-based series of 1586 adults with suspected or confirmed hematological malignancies were successfully cytogenetically investigated at a single center. Eighty-six cases were excluded due to unretrievable medical records or if analyzed only in remission or at relapse. The remaining 1500 medical records were reviewed regarding morphology and clinical parameters in order to investigate possible associations between karyotypic pattern (normal, 1, 2 or complex anomalies; specific abnormalities) and gender, age and morphological subgroups. The impact of time-period, i.e. 1976-87 vs. 1988-93, and referring center on cytogenetic findings was also studied. A total of 372 acute myeloid leukemias (AML), 389 myelodysplastic syndromes (MDS), 64 acute lymphoblastic leukemias (ALL) and 262 chronic myeloid leukemias (CML) were identified, altogether 1087 cases. Patients with other (n=261) or no hematological malignancies (n = 152) were excluded from the present analysis. Cytogenetic abnormalities were detected in 52% AML, 51 % MDS, 68% ALL and 97% CML, frequencies that did not differ significantly between the 2 time periods or referring centers. No significant age- or gender-related differences in karyotypic patterns were discerned in AML, MDS, ALL or CML, whereas the karyotypic patterns varied among the FAB groups in both AML (p= 0.001) and MDS (p < 0.001). The specific abnormalities t(8;21), t(15;17) and inv(16) were more common (p < 0.001) in younger AML patients and 5q- was more frequent in females with MDS (p<0.001). These findings indicate, in contrast to previous series, that neoplasia-associated karyotypic aberrations are not more common among older patients or in males.

Fusion of ETV6 to the Caudal-Related Homeobox Gene CDX2 in Acute Myeloid Leukemia With the t(12;13)(p13;q12)

The t(12;13)(p13;q12) is a rare, recurrent translocation reported in a range of hematological malignancies. We have analyzed the molecular basis of this lesion in three patients with acute myeloid leukemia (AML), two of whom were known to have chromosome 12 breakpoints within the ETV6 gene. Fluorescence in situ hybridization (FISH) with ETV6 cosmids indicated that this gene was also disrupted in the third patient, while the normal ETV6 allele was retained. 3′ rapid amplification of cDNA ends (RACE) polymerase chain reaction (PCR) from bone marrow mRNA of this individual identified a novel sequence fused to ETV6 that was homologous to a region just upstream of the mouse CDX2 homeobox gene, the human homologue of which has previously been mapped to chromosome 13q12. PCR primers designed to amplify an ETV6-CDX2 fusion identified two major transcripts from this patient. First, a direct in-frame fusion between exon 2 of ETV6 and exon 2 of CDX2, and second, a transcript that had an additional sequence of unknown origin spliced between these same exons. Surprisingly, apparently normal CDX2 transcripts, usually expressed only in intestinal epithelium, were also detectable in cDNA from this patient. Neither normal nor fusion CDX2 mRNA was detectable in the two other patients with a t(12;13), indicating that this translocation is heterogeneous at the molecular level. Reverse transcription-PCR analysis showed that CDX2 mRNA, but not ETV6-CDX2 mRNA, was strongly expressed in 1 of 10 patients with chronic myeloid leukemia in transformation, suggesting that deregulation of this gene may be more widespread in leukemia. CDX2 is known to regulate class I homeobox genes and its expression in hematopoietic cells may critically alter the balance between differentiation and proliferation.

Loss of the Y chromosome in bone marrow cells: results on 1907 consecutive cases of leukaemia and preleukaemia

Loss of the Y chromosome with a resulting 45, X0 karyotype is observed in normal bone marrow cells of elderly males but also in haematological malignancies. Whether Y loss in neoplastic cells is related to the process seen in normal ageing or is part of the carcinogenic process is unknown. The present study concerns the cytogenetic data from 1907 consecutive leukaemic or preleukaemic male patients with special regard to the presence or absence of the Y chromosome. Sixty-five patients (3.4%) had a 45, X-Y clone in their bone marrow (BM) cells. Loss of Y was rare below the age of 50 but increased in older patients, reaching 25% of the men over 80. Sixteen patients (0.08%) had more than 90% X0 cells in their BM. A correlation between Y loss and leukaemia could be established in seven cases, three of which were acute myeloid leukaemia M2 subtype where -Y is known to be a secondary event. In three other cases, -Y was part of a complex karyotype. Only one patient exhibited a 45, X0 karyotype, with no other rearrangement, that could be positively correlated with the neoplastic process.

Fusion of ETV6 to the Caudal-Related Homeobox Gene CDX2 in Acute Myeloid Leukemia With the t(12;13)(p13;q12)

The t(12;13)(p13;q12) is a rare, recurrent translocation reported in a range of hematological malignancies. We have analyzed the molecular basis of this lesion in three patients with acute myeloid leukemia (AML), two of whom were known to have chromosome 12 breakpoints within the ETV6 gene. Fluorescence in situ hybridization (FISH) with ETV6 cosmids indicated that this gene was also disrupted in the third patient, while the normal ETV6 allele was retained. 3′ rapid amplification of cDNA ends (RACE) polymerase chain reaction (PCR) from bone marrow mRNA of this individual identified a novel sequence fused to ETV6 that was homologous to a region just upstream of the mouse CDX2 homeobox gene, the human homologue of which has previously been mapped to chromosome 13q12. PCR primers designed to amplify an ETV6-CDX2 fusion identified two major transcripts from this patient. First, a direct in-frame fusion between exon 2 of ETV6 and exon 2 of CDX2, and second, a transcript that had an additional sequence of unknown origin spliced between these same exons. Surprisingly, apparently normal CDX2 transcripts, usually expressed only in intestinal epithelium, were also detectable in cDNA from this patient. Neither normal nor fusion CDX2 mRNA was detectable in the two other patients with a t(12;13), indicating that this translocation is heterogeneous at the molecular level. Reverse transcription-PCR analysis showed that CDX2 mRNA, but not ETV6-CDX2 mRNA, was strongly expressed in 1 of 10 patients with chronic myeloid leukemia in transformation, suggesting that deregulation of this gene may be more widespread in leukemia. CDX2 is known to regulate class I homeobox genes and its expression in hematopoietic cells may critically alter the balance between differentiation and proliferation.

Duplication of band 12q24 in acute myeloblastic leukemia

Cytogenetic studies of two patients with acute myeloblastic leukemia, classified as M1 and M2, showed a partial duplication of the distal part of the long arm of chromosome 12 (12q24) as the sole detectable chromosome abnormality. High white blood cell count was common to the two leukemic children. Fluorescence in situ hybridization analysis with the use of a whole-chromosome 12 painting probe and a telomeric probe confirmed the apparent absence of any translocation. The genes involved in the duplication could not be ascertained, but several candidate genes such as growth-factor receptors or genes encoding transcription factors localized to 12q22-q24 should be investigated in the molecular analysis of these duplications.

A rare variant translocation t(3;8)(q29;q22) without AML1/ETO fusion transcript in a case of oligoblastic leukemia

A 43-year-old man with oligoblastic leukemia and t(3;8) variant translocation is reported. At first he was classified as refractory anemia with excess of blasts in transformation according to the FAB criteria for myelodysplastic syndrome. Remission was obtained after intensive chemotherapy. After 8 months, a relapse occurred as overt M2 AML. At presentation chromosome study of bone marrow cells using R- and G-bandings revealed 45,X, -Y,t(3;8)(q29;q22) in 35 of the 42 metaphases analyzed and 46,XY,t(3;8) in one metaphase in addition to normal karyotype in the other six metaphases. However, RT-PCR assay showed no AML1/ETO fusion transcript. At relapse, a karyotype of 46, XY,t(3;8), deletion(4)(p14), add(7)(q32) was observed in all abnormal cells indicating a clonal karyotypic evolution. We believed that this case should be diagnosed as an early form of M2 AML initially. It may be the first case of oligoblastic leukemia with t(3;8) variant translocation. Further study is needed to elucidate its molecular entity.

Translocation (1;22) in refractory anemia and the prognostic significance of karyotypic abnormalities in refractory anemia

The most common cytogenetic abnormalities associated with myelodysplastic syndromes are deletions of chromosomes 5 and 7 and trisomy 8. Reciprocal translocation is relatively uncommon in refractory anemia. We describe a case of refractory anemia associated with trisomy 8 and a derivative chromosome 22 resulting from t(1;22)(q11;q11.2). The diseases and the role of the various genes that are mapped to these breakpoints are discussed. The prognostic significance of karyotypic abnormalities in refractory anemia are reviewed.

Trisomy 15 associated with loss of the Y chromosome in bone marrow: a possible new aging effect

Trisomy 15 as a single autosomal abnormality is a rare finding in hematological disorders and has not as yet been associated with any specific disease type. We report 20 cases of trisomy 15 observed in the bone marrow of patients referred for a suspected hematological malignancy. Most patients were elderly, and a marked male predominance was evident. Aneuploidy for the Y chromosome was observed in addition to +15 in 11 out of 15 male patients. A myelodysplastic disorder (MDS) was confirmed in six cases, and acute myeloid leukemia (AML) in one. There was no evidence of malignant hematological diseases in the remaining 13 patients. We propose that there may be an association between loss of the Y chromosome and trisomy 15 and that trisomy 15, like missing Y, may not always be a marker of malignancy, but may reflect an underlying age effect. The possibility that its presence may herald the development of a malignant condition cannot, however, be excluded.

Dyshematopoiesis in de novo acute myeloid leukemia: cell biological features and prognostic significance

Dyshematopoiesis was found in 44 (42.3%) of 104 cases of de novo acute myeloid leukemia (AML). Dyshematopoietic AML (dys-AML) and AML without hematopoietic dysplasia (non-dys-AML) were compared with regard to biological, hematological, immunophenotypic, and cytogenetic parameters as well as prognostic criteria. Median age of patients was 55 years in both groups. In dys-AML, the median leukocyte count (p = 0.04), peripheral blast (p = 0.02) and medullary blast cell count (p < 0.001) were significantly decreased, whereas the median platelet count (p - 0.04) was increased. Immunophenotyping demonstrated that leukemic blast cells in dys-AML more frequently expressed the adhesion molcules CD54 (p = 0.05) and CD58 (p = 0.08) than leukemic cells in non-dys-AML. Cytogenetically, we distinguished two karyotypic patterns, one group with a normal karyotype or prognostically favorable single chromosome aberrations ("P(0)-karyotype"), and another one with unfavorable single aberrations or complex aberrations ("P(1)-karyotype"). The incidence of these groups was not significantly different between dys-AML and non-dys-AML. Complete remission rate (CRR) after induction chemotherapy (p = 0.03) and overall survival time (OS; p = 0.03) were significantly lower in dys-AML. In addition, median disease free survival (DFS; p = n.s.) was inferior compared to non-dys-AML. In the dys-AML as well as in the non-dys-AML patient group, CRR, DFS, and OS were decreased in the P(1)-compared to the P(0)-subgroup. We conclude that dyshematopoietic AML is characterized by specific cell biological features and that hematopoietic and cytogenetic status represent complementary prognostic factors in de novo AML.

Myelodysplastic syndromes in Thailand: a retrospective pathologic and clinical analysis of 117 cases

To gain more insight into the understanding of myelodysplastic syndromes (MDS) as they occur in Thailand, a retrospective clinicopathologic analysis was conducted in patients (age > 15 years) diagnosed as MDS from January 1992 to December 1996 at the five major medical centers in various geographic regions of the country. The central reviewers independently examined the bone marrow and peripheral blood smears of all the patients and classify the disease according to the French-British-American (FAB) classification. There were a total of 117 eligible patients. The median age of the patients was 56 years (range 16-86). The male:female ratio was 1:1. Thirty-two percent of the patients were younger than 40 years. The frequency of the FAB subtypes was RA/RARS, 54.7; RAEB, 23.1; CMML, 9.4; and RAEB-T, 12.8%. Anemia was the most common symptom presenting in 84.6% of the patients. In the 34 patients in whom the cytogenetics in the bone marrow were analysed, 44.1% revealed abnormalities. Of these, monosomy 7 and trisomy 8 were the most common aberration, each being detected in 26.7% of the patients. Transfusions were the main therapeutic modality in 80% of the patients. Kaplan-Meier analysis revealed a 5 year survival rate of 29% for the whole group with a median survival of 24 months. Twenty-five percent of the patients had progressed to acute myelogenous leukemia (AML) with a median time to disease-progression of 23 months. The median survival for RA/RARS, RAEB, CMML and RAEB-T were 58.4, 19.9, 10.7 and 8.7 months, respectively (P < 0.001). The stepwise Cox regression analysis revealed the percentage of blasts in the bone marrow as the only parameter significantly associated with survival and disease progression. On comparison with data from other countries, the age of Thai patients with MDS is considerably lower than the western population but is comparable to other asian countries. The distribution of the FAB subtypes and the survival of the patients are similar. The major prognostic features, however, lie in the percentage of blasts in the bone marrow rather than the degree of the observed cytopenia.

A detailed physical and transcriptional map of the region of chromosome 20 that is deleted in myeloproliferative disorders and refinement of the common deleted region

Acquired deletions of the long arm of chromosome 20 are the most common chromosomal abnormality seen in polycythemia vera and are also associated with other myeloid malignancies. Such deletions are believed to mark the site of one or more tumor suppressor genes, loss of which perturbs normal hematopoiesis. A common deleted region (CDR) has previously been identified on 20q. We have now constructed the most detailed physical map of this region to date--a YAC contig that encompasses the entire CDR and spans 23 cM (11 Mb). This contig contains 140 DNA markers and 65 unique expressed sequences. Our data represent a first step toward a complete transcriptional map of the CDR. The high marker density within the physical map permitted two complementary approaches to reducing the size of the CDR. Microsatellite PCR refined the centromeric boundary of the CDR to D20S465 and was used to search for homozygous deletions in 28 patients using 32 markers. No such deletions were detected. Genetic changes on the remaining chromosome 20 may therefore be too small to be detected or may occur in a subpopulation of cells.

dic(5;17): a recurring abnormality in malignant myeloid disorders associated with mutations of TP53

We have identified three unbalanced translocations involving chromosomes 5 and 17, der(5)t(5;17), der(17)t(5;17), and dic(5;17), in the malignant cells from 17 patients with myeloid neoplasms. Six patients had a primary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) de novo; ten patients had therapy-related MDS and/or AML (t-MDS/t-AML), and one patient had chronic myelogenous leukemia in myeloid blast phase. Two of the six patients with MDS or AML de novo had extensive exposure to industrial solvents, and one patient had Seckel syndrome. The primary diagnoses for the ten patients with t-MDS/t-AML were breast carcinoma and Hodgkin's disease in two patients each, and non-Hodgkin's lymphoma, multiple myeloma, chronic lymphocytic leukemia, ovarian carcinoma, thyroid carcinoma, and rhabdomyosarcoma in one patient each. Four patients had received both prior chemotherapy and radiotherapy, four others received prior chemotherapy only, and the remaining two patients only prior radiotherapy. Fluorescence in situ hybridization of centromere-specific probes for chromosomes 5 and 17 revealed that a dicentric rearrangement was the most common (13/16 patients examined). The genetic consequences of these chromosomal rearrangements are partial monosomy for 5q and 17p. Two of six patients examined had point mutations in TP53, suggesting that loss of function of TP53 in addition to loss of a tumor suppressor gene on 5q may be involved in the pathogenesis of the malignant disease in some of these patients.

Clinical aspects, cytogenetics and disease evolution in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) is a morphologically characterized hematologic entity that is one of the clonal myeloproliferative disorders. Approximately 50 approximately 70% of MDS patients have cytogenetic abnormalities; these are usually chromosomal deletions, but some involve translocations such as t(1;7) (q10;p10). Translocations involving chromosomal regions 3q26 or 22q11 are often therapy-related. Recent studies have demonstrated that cytogenetic changes in MDS patients have clinical relevance. Accordingly, there are now scoring systems for predicting the prognoses of MDS patients. In this review, we describe the clinical significance of cytogenetic changes in MDS. We include MDS with some atypical forms, such as MDS with hypocellular bone marrow, MDS with minimal dysplasia, and MDS with myelofibrosis.

Diagnostic and prognostic significance of cytogenetics in adult primary myelodysplastic syndromes

Cytogenetic analysis has proven to be a mandatory part of the diagnosis of myelodysplastic syndromes (MDS) as well as a major indicator for predicting clinical course and outcome. This review concentrates on the cytogenetic classifications, the incidence and types of chromosome defects and the prognostic significance of the karyotype in adult primary MDS. Two cytogenetic classifications are currently used: one is based on the karyotype complexity (normal, single, double or complex defects), the other on clonal status (all metaphases normal, abnormal or admixture of normal and abnormal clones). Chromosome abnormalities are of both numerical and structural types. Aside from the 5q-syndrome, no specific clinico-cytogenetic entity has been reported. However, several distinct clinical and cellular features have been identified that correlate with the presence of specific chromosome defects such as inv(3)/t(3;3), +6, t(5;12), del(17p) and del(20q). The presence of complex defects is associated with reduced survival and a high risk of leukemic transformation. Among single defects, specific abnormalities may define distinct prognostic groups. Patients with del(5q) as a sole chromosome defect and a refractory anemia without excess of blasts have a favourable prognosis. For patients with trisomy 8 or monosomy 7 there may be distinct types of clinical evolution. Most patients with the 3q21q26 syndrome have a short survival. The presence of two chromosome defects may constitute an independent cytogenetic entity probably associated with relative poor prognosis. Karyotypic evolution generally represents a poor risk factor. The combination of cytogenetics with clinical and hematological features has proven to provide for a better prediction of patients' survival, leukemic transformation and response to treatment. Several scoring systems have been developed. They have to be improved by the study of new patients according to strict clinical and cytogenetic criteria and by the addition of newly recognized prognostic indicators such as histopathological features and molecular genetic mutations.