Myelodysplastic syndrome in a child with constitutional trisomy 8 mosaicism and normal phenotype

Cytogenetics in the management of clonal chromosomal abnormalities of undetermined significance and persistent polyclonal B-cell lymphocytosis: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Acquired clonal chromosomal abnormalities (CAs) are usually considered to be disease-related. However, when a CA of this type is the only abnormality present (and especially in small clones), the clinical significance is unclear. Here, we review the literature on recurrent CAs whose significance is regularly subject to debate. Our objective was to help with their interpretation and develop guidelines for sex chromosome loss, trisomy 15, trisomy 8, deletion 20q and other isolated non-myelodysplastic neoplasm (MDS)-defining CAs. We suggest that non-MDS-defining CAs correspond to clonal hematopoiesis of indeterminate potential (CHIP) in the absence of cytopenia and clonal cytopenia of undetermined significance (CCUS) in the presence of cytopenia. Lastly, we review the literature on persistent polyclonal binucleated B-cell lymphocytosis; although usually benign, this condition may correspond to a premalignant state.

Cytogenetics in the management of hematologic neoplasms with germline predisposition: guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

The number of predisposing genes is continuously growing with the widespread availability of DNA sequencing, increasing the prevalence of hematologic malignancies with germline predisposition. Cytogenetic analyses provide an effective approach for the recognition of these malignancies with germline predisposition, which is critical for proper diagnosis, optimal treatment and genetic counseling. Based on the World Health Organization and the international consensus classifications as well as the European LeukemiaNet recommendations, this review first presents an advanced classification of neoplasms with germline predisposition focused on the acquired cytogenetic alterations during leukemogenesis. The various genetic rescue mechanisms and the progression to transformation are then explained. The review also outlines the specific constitutional and somatic cytogenetic aberrations indicative of germline predisposition disorders in B-acute lymphoblastic leukemia (ALL), T-ALL, bone marrow failure syndrome and myeloid neoplasms. An emphasis is made on monosomy 7 in the predisposition field, its frequency and diagnosis impact as well as its various circumstances of occurrence. Lastly, we propose cytogenetic technical recommendations and guidelines for clinical reporting of these specific aberrations.

Modeling specific aneuploidies: from karyotype manipulations to biological insights

An abnormal chromosome number, or aneuploidy, underlies developmental disorders and is a common feature of cancer, with different cancer types exhibiting distinct patterns of chromosomal gains and losses. To understand how specific aneuploidies emerge in certain tissues and how they contribute to disease development, various methods have been developed to alter the karyotype of mammalian cells and mice. In this review, we provide an overview of both classic and novel strategies for inducing or selecting specific chromosomal gains and losses in human and murine cell systems. We highlight how these customized aneuploidy models helped expanding our knowledge of the consequences of specific aneuploidies to (cancer) cell physiology.

Trisomy 8 mosaicism in the placenta: A Danish cohort study of 37 cases and a literature review

OBJECTIVE

To evaluate the risk of fetal involvement when trisomy 8 mosaicism (T8M) is detected in chorionic villus samples (CVS).

METHODS

A retrospective descriptive study of registered pregnancies in Denmark with T8M in CVS identified through a database search and a review of published cases of T8M found through a systematic literature search and inclusion of cross references. Pregnancies with T8M in CVS and no additional numerical chromosomal aberrations were included.

RESULTS

A total of 37 Danish cases and 60 published cases were included. T8M detected in a CVS was associated with fetal involvement in 18 out of 97 pregnancies (18.6% [95%CI: 11.4-27.7]). Eight out of 70 (11.4% [95%CI: 5.1-21.3]) interpreted prenatally to be confined placental mosaicism (CPM) were subsequently found to be true fetal mosaicisms (TFM).

CONCLUSION

T8M detected in CVS poses a significant risk of fetal involvement, and examination of amniotic fluid (AF) and/or fetal tissue should be offered. However, a normal result of AF still has a considerable residual risk of fetal involvement. Genetic counselling at an early gestational age is essential, and follow-up ultrasonography should be performed to predict fetal involvement if possible.

Myelodysplastic and myeloproliferative disorders of childhood

Myelodysplastic syndrome (MDS) and myeloproliferative disorders are rare in children; they are divided into low-grade MDS (refractory cytopenia of childhood [RCC]), advanced MDS (refractory anemia with excess blasts in transformation), and juvenile myelomonocytic leukemia (JMML), each with different characteristics and management strategies. Underlying genetic predisposition is recognized in an increasing number of patients. Germ line GATA2 mutation is found in 70% of adolescents with MDS and monosomy 7. It is challenging to distinguish RCC from aplastic anemia, inherited bone marrow failure, and reactive conditions. RCC is often hypoplastic and may respond to immunosuppressive therapy. In case of immunosuppressive therapy failure, hypercellular RCC, or RCC with monosomy 7, hematopoietic stem cell transplantation (HSCT) using reduced-intensity conditioning regimens is indicated. Almost all patients with refractory anemia with excess blasts are candidates for HSCT; children age 12 years or older have a higher risk of treatment-related death, and the conditioning regimens should be adjusted accordingly. Unraveling the genetics of JMML has demonstrated that JMML in patients with germ line PTPN11 and CBL mutations often regresses spontaneously, and therapy is seldom indicated. Conversely, patients with JMML and neurofibromatosis type 1, somatic PTPN11, KRAS, and most of those with NRAS mutations have a rapidly progressive disease, and early HSCT is indicated. The risk of relapse after HSCT is high, and prophylaxis for graft-versus-host disease and monitoring should be adapted to this risk.

Trisomy 8 in pediatric acute myeloid leukemia: A NOPHO-AML study

Trisomy 8 (+8) is a common cytogenetic aberration in acute myeloid leukemia (AML); however, the impact of +8 in pediatric AML is largely unknown. We retrospectively investigated 609 patients from the NOPHO-AML database to determine the clinical and cytogenetic characteristics of +8 in pediatric AML and to investigate its prognostic impact. Complete cytogenetic data were available in 596 patients (98%) aged 0-18 years, diagnosed from 1993 to 2012, and treated according to the NOPHO-AML 1993 and 2004 protocols in the Nordic countries and Hong Kong. We identified 86 patients (14%) with +8. Trisomy 8 was combined with other cytogenetic aberrations in 68 patients (11%) (+8 other) and in 18 patients (3%), it was the sole abnormality (+8 alone). Trisomy 8 was associated with FAB M5 (36%) but otherwise clinically comparable with non-trisomy 8 patients. Trisomy 8 was favorable in patients of young age and with t(9;11). Trisomy 8 alone was associated with older age (median age 10.1 years), FAB M2 (33%), and FLT3-ITD mutations (58%). The 5-year event-free survival for patients with +8 alone was 50% and 5-year overall survival was 75%. In conclusion, +8 is one of the most common cytogenetic aberrations in pediatric AML. Trisomy 8 positive AML is a heterogeneous group and the majority of cases have additional cytogenetic aberrations. Patients with +8 alone differed from patients with +8 other and were associated with older age, FAB M2, and FLT3-ITD aberrations. There were no differences in survival despite the more frequent occurrence of FLT3-ITD in +8 alone. © 2016 Wiley Periodicals, Inc.

Trisomy 8, a Cytogenetic Abnormality in Myelodysplastic Syndromes, Is Constitutional or Not?

Isolated trisomy 8 is not considered presumptive evidence of myelodysplastic syndrome (MDS) in cases without minimal morphological criteria. One reason given is that trisomy 8 (+8) can be found as a constitutional mosaicism (cT8M). We tried to clarify the incidence of cT8M in myeloid neoplasms, specifically in MDS, and the diagnostic value of isolated +8 in MDS. Twenty-two MDS and 10 other myeloid neoplasms carrying +8 were studied. Trisomy 8 was determined in peripheral blood by conventional cytogenetics (CC) and on granulocytes, CD3+ lymphocytes and oral mucosa cells by fluorescence in situ hybridization (FISH). In peripheral blood CC, +8 was seen in 4/32 patients. By FISH, only one patient with chronic myelomonocytic leukemia showed +8 in all cell samples and was interpreted as a cT8M. In our series +8 was acquired in all MDS. Probably, once discarded cT8M by FISH from CD3+ lymphocytes and non-hematological cells, +8 should be considered with enough evidence to MDS.

The epigenetic landscape of aneuploidy: constitutional mosaicism leading the way?

The role of structural genetic changes in human disease has received substantial attention in recent decades, but surprisingly little is known about numerical chromosomal abnormalities, even though they have been recognized since the days of Boveri as partaking in different cellular pathophysiological processes such as cancer and genomic disorders. The current knowledge of the genetic and epigenetic consequences of aneuploidy is reviewed herein, with a special focus on using mosaic genetic syndromes to study the DNA methylation footprints and expressional effects associated with whole-chromosomal gains. Recent progress in understanding the debated role of aneuploidy as a driver or passenger in malignant transformation, as well as how the cell responds to and regulates excess genetic material in experimental settings, is also discussed in detail.

Cytogenetics and clinical features of pediatric myelodysplastic syndrome in Japan

We analyzed the cytogenetics and clinical features of pediatric myelodysplastic syndrome (MDS) in Japan. Data on patients (<16 years) diagnosed with MDS from 1990 to 2000 were retrospectively collected from pediatric hematologists in 234 institutions. Chromosome analysis was successfully performed in 255 of 277 MDS patients. The numbers of patients with refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess of blasts (RAEB), refractory anemia with excess of blasts in transformation (RAEBt), chronic myelomonocytic leukemia, and juvenile myelomonocytic leukemia were 67 (24%), 51 (18%), 51 (18%), 20 (7%), and 65 (23%), respectively. The other 23 patients (8%) could not be classified specifically. The distribution of childhood MDS in Japan according to the French-American-British subclassification was similar to that in other countries. However, we identified a higher incidence of therapy-related cases. As for relationship between cytogenetics and prognoses, abnormal karyotypes were related to poorer prognoses than normal karyotype (P < 0.01). However, patients with trisomy 8 had prognoses comparable to those with normal karyotypes. Complex karyotypes were associated with poorer prognoses among RAEB and RAEBt patients. In conclusion, prognosis of pediatric MDS is related to cytogenetics. A more precise diagnosis and classification system is needed for childhood MDS.

Array-CGH as an adjuvant tool in cytogenetic diagnosis of pediatric MDS and JMML

Myelodysplastic syndromes (MDS) and juvenile myelomonocytic leukemia (JMML) are rare clonal hematopoietic diseases presented in the childhood. Both diseases exhibit abnormal karyotype and/or monosomy of chromosome 7 in a subgroup of patients. We screened for copy number variations (CNVs) by array-comparative genomic hybridization (aCHG) the DNA from bone marrow of six MDS and four JMML pediatric patients. Array-CGH analysis identified five cases (50%) with monosomy 7, disclosing the chromosome 7 monosomy in two patients whose samples could not be evaluated by other methods. We identified CNVs in six patients, one of which displayed loss of LMO2, an oncogene that plays a central role in hematopoietic development. Our results suggest that array-CGH is a reliable and accurate technique to identify genomic alterations in MDS and JMML.

Trisomy 8 in leukemia: A GCRI experience

Trisomy of chromosome 8 is frequently reported in myeloid lineage disorders and also detected in lymphoid neoplasms as well as solid tumors suggesting its role in neoplastic progression in general. It is likely to be a disease-modulating secondary event with underlying cryptic aberrations as it has been frequently reported in addition to known abnormalities contributing to clinical heterogeneity and modifying prognosis. Here, we share our findings of trisomy 8 in leukemia patients referred for diagnostic and prognostic cytogenetic assessment. Total 60 cases of trisomy 8, as a sole anomaly or in addition to other chromosomal aberrations, were reported (January 2005–September 2008). Unstimulated bone marrow or blood samples were cultured, followed by GTG banding and karyotyping as per the ISCN 2005. Patients with +8 were chronic myeloid leukemia (CML) (36), acute myeloid leukemia (AML) (17), and acute lymphoblastic leukemia (ALL) (7). In 7 patients, trisomy 8 was the sole anomaly, whereas in 6 patients +8 was in addition to normal clone, in 47 patients, the +8 was in addition to t(9;22), t(15;17), and others, including 3 with tetrasomy 8. Only one patient showed constitutional +8. The present study will form the basis of further cumulative studies to correlate potential differential effects of various karyotypic anomalies on disease progression and survival following a therapeutic regime. To unravel the role of extra 8 chromosome, constitutional chromosomal analysis and uniparental disomy will be considered.

t(9;22)(q34;q11.2) is a recurrent constitutional non-Robertsonian translocation and a rare cytogenetic mimic of chronic myeloid leukemia

The diagnosis of hematologic malignancy can be greatly aided by the detection of a cytogenetic abnormality. However, care must be taken to ensure that constitutional chromosomal abnormalities are not misattributed to a putative population of malignant cells. Here we present an unusual case in which a constitutional balanced t(9;22)(q34;q11.2) cytogenetically mimicked the acquired, t(9;22)(q34;q11.2), that is characteristic of chronic myeloid leukemia. Of special note, fluorescence in situ hybridization (FISH) analysis for this constitutional translocation (9;22)(q34;q11.2) using standard probes for BCR and ABL1 resulted in an abnormal pattern that was potentially misinterpretable as a BCR-ABL1 fusion. This is the first reported FISH analysis of a constitutional t(9;22)(q34;q11.2), and overall only the second report of such an abnormality. In light of the isolated prior report, our case also suggests that the constitutional t(9;22)(q34;q11.2) is one of the very few recurrent constitutional non-Robertsonian translocations described in humans. Our case underscores the necessity of complete clinical and laboratory correlation to avoid misdiagnosis of myeloid malignancy in the setting of rare constitutional cytogenetic abnormalities.

Mosaiktrisomie 8p11.21q11.21 als Prädisposition für myeloische Leukämien

Bei der juvenilen myelomonozytären Leukämie (JMML) handelt es sich um eine myeloproliferative Erkrankung der frühen Kindheit. Bei vielen Patienten lassen sich zugrunde liegende somatische, aber auch konstitutionelle Mutationen in NRAS, KRAS, PTPN11, NF1 und CBL nachweisen. Zur Identifizierung submikroskopischer Veränderungen, die für die leukämische Transformation von Bedeutung sein können, wurden 20 JMML-Proben mittels hochauflösender Oligo-Microarray-basierter komparativer genomischer Hybridisierung (aCGH) untersucht. Bei 2 von 10 Patienten mit submikroskopischen Aberrationen konnte ein nahezu identischer Zugewinn von Chromosom 8 gezeigt werden, der sich in weiteren Untersuchungen als konstitutionelles Mosaik darstellte. Eine Übersicht von 27 Patienten mit einem konstitutionellen Trisomie-8-Mosaik (cT8M) und maligner Neoplasie zeigte, dass es sich meist um myeloische Neoplasien, auch JMML, handelt. Durch unsere Untersuchungen konnte die kritische Region auf Chromosom 8, deren Loci mutmaßlich an der Leukämieentstehung und/oder Progression beteiligt sein können, dramatisch reduziert werden: 8p11.21q11.21. Es bleibt zu klären in welcher Form das partielle Trisomie-8-Mosaik an der Leukämieentstehung beteiligt ist und in welcher Weise dies für verschiedenen Mutationssubtypen der JMML eine Rolle spielt.

Constitutional trisomy 8p11.21-q11.21 mosaicism: a germline alteration predisposing to myeloid leukaemia

Juvenile myelomonocytic leukaemia (JMML) is a unique myeloproliferative disorder of early childhood. Frequently, mutations in NRAS, KRAS, PTPN11, NF1 or CBL are found in these patients. Monosomy 7 is the most common cytogenetic aberration. To identify submicroscopic genomic copy number alterations, 20 JMML samples were analysed by comparative genomic hybridization. Ten out of 20 samples displayed additional submicroscopic alterations. In two patients, an almost identical gain of chromosome 8 was identified. In both patients, fluorescence in situ hybridization confirmed a constitutional partial trisomy 8 mosaic (cT8M). A survey on 27 cT8M patients with neoplasms showed that 21 had myeloid malignancies, and five of these had a JMML. Notably, the region gained in our cases is the smallest gain of chromosome 8 reported in cT8M cases with malignancies so far. Our results dramatically reduce the critical region to 8p11.21q11.21 harbouring 31 protein coding genes and two non-coding RNAs, e.g. MYST3, IKBKB, UBE2V2, GOLGA7, FNTA and MIR486--a finding with potential implications for the role of somatic trisomy 8 in myeloid malignancies. Further investigations are required to more comprehensively determine how constitutional partial trisomy 8 mosaicisms may contribute to leukaemogenesis in different mutational subtypes of JMML and other myeloid malignancies.

Constitutional aneuploidy and cancer predisposition

Constitutional aneuploidies are rare syndromes associated with multiple developmental abnormalities and the alterations in the risk for specific cancers. Acquired somatic chromosomal aneuploidies are the most common genetic aberrations in sporadic cancers. Thus studies of these rare constitutional aneuploidy syndromes are important not only for patient counseling and clinical management, but also for deciphering the mechanisms by which chromosomal aneuploidy affect cancer initiation and progression. Here we review the major constitutional aneuploidy syndromes and suggest some general mechanisms for the associated cancer predisposition.

Trisomy 8 in an allogeneic stem cell transplant recipient representative of a donor-derived constitutional abnormality

Trisomy 8 is a common cytogenetic abnormality in myeloid malignancies. It can also be present constitutionally and is associated with a wide range of phenotypes. We report a case of a 20-year-old woman with acute myelogenous leukemia associated with the 11q23/MLL translocation who underwent allogeneic hematopoietic stem cell transplantation (HSCT) from a healthy, unrelated 26-year-old female. Cytogenetics on a bone marrow biopsy and aspirate performed 71 days after transplant to evaluate pancytopenia identified trisomy 8 in 6 of 7 cells examined. The bone marrow was hypocellular but normal by morphology and flow cytometry. Fluorescent in situ hybridization (FISH) for the original 11q23/MLL translocation was negative. Chimerism analysis using multiplex polymerase chain reaction to amplify an informative short tandem repeat demonstrated 97% donor cells. These findings were confirmed by repeat bone marrow biopsies at Day 110 after transplant and 1 year after transplant. With resolution of comorbid illness, the patient's peripheral blood counts recovered and remained normal at 1 year after HSCT. FISH analysis of a cryopreserved sample of the donor graft showed trisomy 8 in 120 of 200 cells examined. This represents the first reported case of a person with constitutional trisomy 8 mosaicism serving as a stem cell donor. The case illustrates the importance of identifying donor-derived constitutional abnormalities to avoid the assumption that these cytogenetic abnormalities after HSCT are representative of malignant disease.

Aphthous ulcerations associated with trisomy 8–positive myelodysplastic syndrome

The association of Behçet's disease with myelodysplastic syndromes has been established in the hematologic, gastrointestinal, and medical genetics literature; trisomy 8 is a feature present in 70% of these reports. Because trisomy 8 is ordinarily present in only 14% of patients with myelodysplastic syndrome, this is a significant overrepresentation. We describe a patient with recurrent aphthous stomatitis who was subsequently diagnosed with trisomy 8-positive myelodysplastic syndrome after an unexplained macrocytosis was further investigated.

A novel t(8;18)(q13;q21) in acute monocytic leukemia evolving from constitutional trisomy 8 mosaicism

Constitutional trisomy 8 mosaicism (CT8M) has been considered to be the first mutation in multistep carcinogenesis. We describe the case of a 38-year-old woman with a normal phenotype who developed to acute monocytic leukemia with a novel t(8;18)(q13;q21). Chromosome analysis and spectral karyotyping showed 47,XX,+8,t(8;18)(q13;q21)[20]. Fluorescence in situ hybridization (FISH) demonstrated that the breakpoint at 18q21 was centromeric to the MALT1 and BCL2 genes. FISH also revealed that trisomy 8 was detected in buccal mucosa cells, indicating that trisomy 8 was a constitutional abnormality. These results suggest that t(8;18)(q13;q21) had a crucial role in the development of leukemia as the second mutation following CT8M.

Constitutional trisomy 8 mosaicism with myelodysplastic syndrome complicated by intestinal Behcet disease and antithrombin III deficiency

Trisomy 8 is the most common acquired chromosomal abnormality associated with myeloid malignancy. As a constitutional trisomy 8 mosaicism (T8M), it exhibits an extremely variable phenotype. In addition, Behcet disease (BD) has been reported as an unusual complication of myelodysplastic syndrome (MDS). To our knowledge, 12 case reports of various hematologic malignancies in patients with T8M and 18 case reports of MDS with acquired trisomy 8 complicated by BD have been published to date. We report a case of constitutional T8M with MDS complicated by intestinal BD and antithrombin III deficiency.

The geldanamycin derivative 17-AAG decreases VEGF secretion and leukemia growth support by trisomy 8 myelodysplastic syndrome bone marrow stromal cells

Stromal cells from a child with constitutional trisomy 8 who developed myelodysplastic syndrome (MDS) were found to produce abnormal levels of various cytokines, including VEGF, and supported the growth of leukemic cells in co-culture assays. This study shows that the geldanamycin derivative 17-AAG effectively reduces the VEGF expression by MDS stromal cells. In co-culture experiments this agent also blocks the ability of the MDS stromal cells to stimulate the growth of leukemic cells. These data provide important initial evidence for the effect of 17-AAG on the marrow microenvironment and its potential use in the treatment of MDS and leukemia.

Constitutional trisomy 8 mosaicism due to meiosis II non-disjunction in a phenotypically normal woman with hematologic abnormalities

Constitutional trisomy 8 mosaicism (CT8M) in liveborns is typically caused by mitotic non-disjunction and exhibits wide phenotypic variability. By contrast, CT8M due to meiotic errors usually results in miscarriage. We describe a case of CT8M due to a paternal meiosis II non-disjunction error. The patient, a 32-year-old woman, was phenotypically normal except for a history of recurrent aphthous ulcers since childhood and a 4-year history of macrocytosis. The ulcers were refractory to steroids, but responded well to thalidomide. To the best of our knowledge, this is the first report of CT8M due to meiotic non-disjunction in a phenotypically normal individual.

Constitutional chromosome aberrations as pathogenetic events in hematologic malignancies

A predisposition to tumor development is associated with some constitutional chromosomal abnormalities. Investigations of families with an apparent hereditary cancer and constitutional chromosome rearrangements have led to the molecular identification of tumor suppressor genes. Under the somatic mutation theory for the development of cancer, two mutational events are required. The first step may be a constitutional event and the second an acquired genetic mutation. Cytogenetic studies were performed on 5633 bone marrow specimens from patients with hematologic malignancies from a single institution. Fifty cases of constitutional chromosome aberrations were detected. Data collected from the literature and from our series are reviewed and compared with the incidence of specific constitutional chromosome aberrations in the newborn population. Possible mechanisms that may predispose individuals with constitutional chromosome aberrations to the development of a hematologic malignancy are reviewed.

Impact of trisomy 8 (+8) on clinical presentation, treatment response, and survival in acute myeloid leukemia: a Southwest Oncology Group study

The prognostic impact of trisomy 8, alone or with other clonal aberrations, was evaluated in 849 patients with previously untreated acute myeloid leukemia (AML) who were registered to 5 Southwest Oncology Group trials. At presentation, 108 (12.7%) patients had +8 in their karyotypes, including 43 (5.1%) patients with +8 as the sole aberration; 307 (36.2%) were normal, and 434 (51.1%) had other cytogenetic abnormalities. Patients with +8 were slightly older (P =.033), had lower WBC (P =.011), and had lower percentages of peripheral blasts (P =.0004) than the patients without +8. Median survival time for all patients with +8 was 9.9 months (95% CI, 6.5-12.5), similar to that of "unfavorable" cytogenetics risk groups (8.3 months; 95% CI, 6.8-9.5.) Patients with +8 had significantly lower peripheral blasts (P =.0002), WBC (P <.0001) counts, and decreased overall survival (OS) than patients with normal cytogenetics (9.9 months vs 15.4 months; P =.006). However, survival of patients with +8 as the sole aberration did not differ significantly from those with normal cytogenetics (P =.36). Thus, the trisomy 8 group as a whole had poor survival, which was largely attributable to worsened outcomes among patients whose trisomy 8 was associated with other unfavorable cytogenetic abnormalities.

Chronic myelomonocytic leukaemia in a child with constitutional partial trisomy 8 mosaicism

We present a 3-year-old boy with constitutional partial trisomy 8 mosaicism (karyotype 47,XY, + del(8)(p12)/46,XY) who developed chronic myelomonocytic leukaemia and we review the few reported cases of constitutional trisomy 8 mosaicism (CT8M) associated with malignancy. This case highlights the association between CT8M and the development of malignancies, haematological malignancies in particular.

Many unbalanced translocations show duplication of a translocation participant. Clinical and cytogenetic implications in myeloid hematologic malignancies

If a translocation is followed by loss of one of the two derivative chromosomes, the result is an unbalanced translocation, showing monosomy for the segments making up the lost derivative. We have found that in most unbalanced translocations, a third event takes place: a morphologically normal copy of one of the two translocation participants is added to the karyotype. This creates a complex abnormal karyotype with monosomy, disomy, and trisomy for different segments of the translocation participants. We have examined 82 unbalanced translocations from 77 patients, 73 of whom had a myeloid hemopoietic malignancy. Acquisition of a normal copy of a translocation participant was found in 49 translocations. Twenty-five of these showed trisomy for 1q. In 16 of the 25 1q-trisomic cases the translocation was t(1;7)(q10;p10) (trisomy for 1q and monosomy for 7q). Patients with trisomy for 1q were younger than the remaining patients. Whereas those with t(1;7))(q10;p10) showed brief survivals, those with trisomy 1q but monosomy for regions other than 7q survived longer than the remaining patients. We conclude that most unbalanced translocations involve a partial trisomy, that 1q is trisomic far more frequently than any other segment, and that partial trisomy is associated with patient age and survival.

Esthesioneuroblastoma is not a member of the primitive peripheral neuroectodermal tumour-Ewing's group

Esthesioneuroblastoma (ENB) is a rare, site-specific, locally aggressive neuronal malignancy so far thought to belong to primitive peripheral neuroectodermal tumour-Ewing's tumour (pPNETs-ETs). Its anatomical location, in addition to morphologic, immunophenotypic and ultrastructural features, suggests its origin in the neuronal or neuroendocrine cells of the olfactory epithelium. However, the cytogenetic and molecular data currently available appear controversial on the presence of the typical translocation t(11;22)(q24;q12) and of trisomy 8, chromosomal changes that characterize the tumours belonging to the pPNETs-ETs. Herein we have analysed five ENB tumour specimens for trisomy 8 by fluorescence in situ hybridization (FISH), for the presence of EWS gene rearrangements by FISH, reverse transcription polymerase chain reaction and Southern blot analyses, as well as for the expression of the Ewing sarcoma-associated MIC2 antigen by immunohistochemistry. Neither EWS/FLI-I, EWS/ERG and EWS/FEV fusion genes nor MIC2 expression were found in any tumour, whereas trisomy 8 was found in one case only. Moreover, DNA from three cases analysed by Southern blot did not show EWS gene rearrangements. Our results support the evidence that ENB is not a member of the pPNETs-ETs.

Constitutional trisomy 8 as first mutation in multistep carcinogenesis: clinical, cytogenetic, and molecular data on three cases

Three patients, with constitutional trisomy 8 mosaicism (CT8M), who developed a malignancy are reported. The diagnoses were refractory anaemia, acute lymphoblastic leukaemia, and idiopathic myelofibrosis. In the child with acute leukaemia, the CT8M was diagnosed at birth due to severe dysmorphisms and malformations; the other two patients showed a milder phenotype, and the CT8M was diagnosed only after the finding of trisomy 8 in neoplastic cells. The review of eight similar, previously reported cases and the clinical, cytogenetic, and molecular studies performed in our patients led us to make the following observations: (I) CT8M predisposes to neoplasms, preferentially to myelo- or lymphoproliferative diseases; (2) a gene dosage effect for glutathione reductase in red blood cells was seen in two of our patients; (3) the wide phenotypic variation of CT8M was confirmed: trisomy 8 in neoplastic cells of phenotypically near-normal cases may be misinterpreted as acquired; and (4) molecular studies suggested a postzygotic origin of the trisomy in our three cases, with the supernumerary chromosome being of paternal origin in one case and of maternal origin in the other two. We postulate that the trisomy 8 in neoplasms may often occur by mitotic nondisjunction in an early embryonic multipotent cell and that what is usually interpreted as an acquired trisomy 8 may in fact be CT8M. The constitutional trisomy 8 would act as a pathogenetically important first mutation in multistep carcinogenesis. Whenever trisomy 8 is found in malignancies, the patient should be reevaluated clinically to exclude CT8M, and CT8M patients should be monitored for the possible development of malignancies.

Aspects of the neoplasms observed in patients with constitutional autosomal trisomy

A review of the literature reveals numerous clinical case reports, systematic histologic analyses, epidemiologic studies, and large series of tumors showing that subjects with trisomy 8, 9, 13, 18, and 21 have an excess of hematologic and various solid tumors compared to the general population. These tumors more frequently affect particular organs for a given type of trisomy. A large proportion of tumors are observed during fetal and neonatal life, are incompletely developed, and subsequently regress. In older children or even adults, tumors are less frequent, are often found on the same organs as earlier in life, are more aggressive, and do not involute. The mechanism responsible for the development of these neoplasms could be similar to that which generates the malformations in these children and may result from cooperation of the chromosomal abnormality with physiologic growth phenomena, which are particularly active early in life. Trisomic subjects must be carefully followed in order to detect tumors as early as possible and to allow treatment under optimal conditions.

Constitutional and acquired trisomy 8

Trisomy 8 is seen in a range of disorders both constitutional and acquired. The full constitutional condition presents with physical stigmata, skeletal abnormalities and a mild to moderately retarded IQ. Trisomy 8 is frequently seen as a mosaic in the blood or in the skin or both. Trisomy 8 as an acquired condition is found in haematological disorders, notably in myelodysplasia (MDS) and acute myeloid leukaemia (AML), and is restricted to the malignant cells. These arise in the bone marrow and may also be found in the peripheral blood. Reported in the issue (Zollino et al. (1995) Leukemia Res. 19(10), 733) is a case of a patient with constitutional trisomy 8 mosaicism who developed myelodysplasia with trisomy 8 in 95-100% of bone marrow cells. Here we consider the implications of this case to the diagnosis of both malignant and constitutional conditions.