Myelodysplastic syndrome associated with monosomy 7 in a child with Bloom syndrome

New-Onset Monosomy 7-Induced Pancytopenia in a 66-Year-Old Woman

Myelodysplastic syndrome (MDS) is characterized by failure to initiate hematopoiesis or impaired maturation of cells, often presenting with pancytopenias with or without associated fatigue, infections, or inappropriate bleeding and bruising. Karyotype analyses of MDS patients commonly show deletion of the q arm of chromosome 7, suggesting loss of this region is likely implicated in the insufficient hematopoiesis seen in MDS. The predisposition to deletion of 7q is commonly inherited, with clinical presentation in early childhood associated with pancytopenia or hematological malignancy. In this case, we present a 66-year-old female who was incidentally found to be pancytopenic in the emergency department while being evaluated for dyspnea, with a bone marrow biopsy later confirming a diagnosis of MDS with monosomy 7. Sporadic loss of 7q can occur at any stage in life without any family history of hematological disease. Our patient has no known personal or family history of MDS, with normal blood counts during hospitalization three years prior, suggesting de novo loss of 7q occurring at greater than 60 years of age.

Single-center pediatric experience with venetoclax and azacitidine as treatment for myelodysplastic syndrome and acute myeloid leukemia

BACKGROUND

The BCL-2 inhibitor venetoclax (ven) has revolutionized the treatment of acute myeloid leukemia (AML) in elderly adults, leading to its recent FDA approval for this population in combination regimens. Although extensive data exist for adult myeloid malignancies, there are limited preclinical data on the efficacy and/or dosing of venetoclax for pediatric myelodysplastic syndrome (MDS) or AML and thus little information to guide use of this regimen in pediatric patients. Our objective was to describe our single-center experience with venetoclax in combination with the hypomethylating agent 5-azacitidine (aza) in pediatric patients with MDS or AML.

PROCEDURE

We conducted a retrospective chart review of patients treated at Children's Hospital Colorado prior to March 2020 with at least one cycle of ven/aza. Patients were included if between the ages of 1 and 25 years with a diagnosis of high-grade MDS or AML. AML patients had relapsed or primary refractory disease or were deemed poor candidates for standard chemotherapy.

RESULTS

Eight patients received ven/aza, two for high-grade MDS and six for AML. Ven/aza was well tolerated by all patients. The most common adverse events seen with this regimen were gastrointestinal and hematologic. Morphologic responses were seen in six patients including both patients with MDS. All four AML responders became minimal residual disease negative. Three responders have thus far proceeded to allogeneic hematopoietic stem cell transplant following ven/aza.

CONCLUSIONS

Our clinical experience suggests that ven/aza is a safe and promising regimen that should be further explored with late-phase clinical trials.

A mechanism for 1,4-Benzoquinone-induced genotoxicity

Benzene is a common environmental toxin and its metabolite, 1-4-Benzoquinone (BQ) causes hematopoietic cancers like myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). BQ has not been comprehensively assessed for its impact on genome maintenance, limiting our understanding of the true health risks associated with benzene exposure and our ability to identify people with increased sensitivity to this genotoxin. Here we analyze the impact BQ exposure has on wild type and DNA repair-defective mouse embryonic stem (ES) cells and wild type human cells. We find that double strand break (DSB) repair and replication fork maintenance pathways including homologous recombination (HR) and Fanconi anemia (FA) suppress BQ toxicity. BQ-induced damage efficiently stalls replication forks, yet poorly induces ATR/DNA-PKCS responses. Furthermore, the pattern of BQ-induced γH2AX and 53BP1foci is consistent with the formation of poly(ADP-ribose) polymerase 1 (PARP1)-stabilized regressed replication forks. At a biochemical level, BQ inhibited topoisomerase 1 (topo1)-mediated DNA ligation and nicking in vitro; thus providing mechanism for the cellular phenotype. These data are consistent with a model that proposes BQ interferes with type I topoisomerase's ability to maintain replication fork restart and progression leading to chromosomal instability that has the potential to cause hematopoietic cancers like MDS and AML.

Acute myeloid leukaemia after treatment for acute lymphoblastic leukaemia in girl with Bloom syndrome

Bloom syndrome (BS) is an inherited genomic instability disorder caused by disruption of the BLM helicase and confers an extreme cancer predisposition. Here we report on a girl with BS who developed acute lymphoblastic leukaemia (ALL) at age nine, and treatment-related acute myeloid leukaemia (t-AML) aged 12. She was compound heterozygous for the novel BLM frameshift deletion c.1624delG and the previously described c.3415C>T nonsense mutation. Two haematological malignancies in a child with BS imply a fundamental role for BLM for normal haematopoiesis, in particular in the presence of genotoxic stress.

Somatic CEBPA mutations are a frequent second event in families with germline CEBPA mutations and familial acute myeloid leukemia

PURPOSE

The transcription factor CCAAT/enhancer binding protein-alpha (CEBPA) is crucial for normal myeloid differentiation. Mutations in the CEBPA gene are found in subsets of patients with acute myeloid leukemia (AML). Recently, three families were reported in whom several family members had germline CEBPA mutations and subsequently developed AML. Whereas familial AML is considered a rare event, the frequency of CEBPA germline mutations in AML is not known.

PATIENTS AND METHODS

In this study, we screened 187 consecutive AML patients for CEBPA mutations at diagnosis. We detected 18 patients (9.6%) with CEBPA mutations. We then analyzed remission samples and constitutive DNA from these patients.

RESULTS

We found that two (11.1%) of 18 AML patients with CEBPA mutations carried a germline N-terminal frameshift CEBPA mutation. Interestingly, additional members in the families of both of these patients have been affected by AML, and the germline CEBPA mutations were also observed in these patients. Additional somatic mutations in AML patients with germline CEBPA mutations in the two families comprised in-frame C-terminal CEBPA mutations in two patients, two nonsilent CEBPA point mutations in one patient, and monosomy 7 in one patient.

CONCLUSION

This study shows, for the first time to our knowledge, that germline CEBPA mutations are frequently observed among AML patients with CEBPA mutations. Including the families with germline CEBPA mutations reported previously, additional somatic CEBPA mutations represent a frequent second event in AML with germline CEBPA mutations. Our data strongly indicate that germline CEBPA mutations predispose to AML and that additional somatic CEBPA mutations contribute to the development of the disease.

Familial myelodysplasia and acute myeloid leukaemia--a review

Familial occurrence of myelodysplasia (MDS) and/or acute myeloid leukaemia (AML) is rare but can provide a useful resource for the investigation of predisposing mutations in these myeloid malignancies. To date, examination of families with MDS/AML has lead to the detection of two culprit genes, RUNX1 and CEBPA. Germline mutations in RUNX1 result in familial platelet disorder with propensity to myeloid malignancy and inherited mutations of CEBPA predispose to AML. Unfortunately, the genetic cause remains obscure in most other reported pedigrees. Further insight into the molecular mechanisms of familial MDS/AML will require awareness by clinicians of new patients with relevant family histories.

Pigmentary disorders in the Mediterranean area

The Mediterranean area represents the area of land that borders the Mediterranean basin. It is composed of several countries that share many geographic and racial characteristics. Although Mediterraneans seem to share common skin type and are subjected to similar enviromental factors, they still represent a genetic and socioeconomic diversity. True prevalence of pigmentary disorders in this area depends on large epidemiologic studies, including countries that are not available. This article, however, highlights and classifies the most important developmental (heritable-genetic) and acquired pigmentary disorders seen and reported in this important area of the world.

Myelodysplastic syndrome associated with monosomy 7 in childhood: a retrospective study

Myelodysplastic syndrome (MDS) is a clonal hematopoietic stem cell disorder characterized by ineffective hematopoiesis, peripheral cytopenia, and dysplastic changes in the bone marrow. Monosomy 7 or partial loss of 7q is a common cytogenetic abnormality in MDS patients and is associated with poor prognosis. This study examined eight patients with monosomy 7 and MDS. Five MDS patients with monosomy 7 progressed to acute leukemia: three cases transformed into acute myelogenous leukemia (AML) in a mean time of only 4.6 months and two cases into acute lymphoblastic leukemia (ALL) in a mean time of 9 months. To our knowledge, this is the first report showing progression of monosomy 7 associated with MDS to ALL in the childhood period.

Mutation of the murine Bloom's syndrome gene produces global genome destabilization

Bloom's syndrome (BS) is a genetic disorder characterized cellularly by increases in sister chromatid exchanges (SCEs) and numbers of micronuclei. BS is caused by mutation in the BLM DNA helicase gene and involves a greatly enhanced risk of developing the range of malignancies seen in the general population. With a mouse model for the disease, we set out to determine the relationship between genomic instability and neoplasia. We used a novel two-step analysis to investigate a panel of eight cell lines developed from mammary tumors that appeared in Blm conditional knockout mice. First, the panel of cell lines was examined for instability. High numbers of SCEs were uniformly seen in members of the panel, and several lines produced chromosomal instability (CIN) manifested by high numbers of chromosomal structural aberrations (CAs) and chromosome missegregation events. Second, to see if Blm mutation was responsible for the CIN, time-dependent analysis was conducted on a tumor line harboring a functional floxed Blm allele. The floxed allele was deleted in vitro, and mutant as well as control subclones were cultured for 100 passages. By passage 100, six of nine mutant subclones had acquired high CIN. Nine mutant subclones produced 50-fold more CAs than did nine control subclones. Finally, chromosome loss preceded the appearance of CIN, suggesting that this loss provides a potential mechanism for the induction of instability in mutant subclones. Such aneuploidy or CIN is a universal feature of neoplasia but has an uncertain function in oncogenesis. Our results show that Blm gene mutation produces this instability, strengthening a role for CIN in the development of human cancer.

Control of translocations between highly diverged genes by Sgs1, the Saccharomyces cerevisiae homolog of the Bloom's syndrome protein

Sgs1 is a RecQ family DNA helicase required for genome stability in Saccharomyces cerevisiae whose human homologs BLM, WRN, and RECQL4 are mutated in Bloom's, Werner, and Rothmund Thomson syndromes, respectively. Sgs1 and mismatch repair (MMR) are inhibitors of recombination between similar but divergent (homeologous) DNA sequences. Here we show that SGS1, but not MMR, is critical for suppressing spontaneous, recurring translocations between diverged genes in cells with mutations in the genes encoding the checkpoint proteins Mec3, Rad24, Rad9, or Rfc5, the chromatin assembly factors Cac1 or Asf1, and the DNA helicase Rrm3. The S-phase checkpoint kinase and telomere maintenance factor Tel1, a homolog of the human ataxia telangiectasia (ATM) protein, prevents these translocations, whereas the checkpoint kinase Mec1, a homolog of the human ATM-related protein, and the Rad53 checkpoint kinase are not required. The translocation structures observed suggest involvement of a dicentric intermediate and break-induced replication with multiple cycles of DNA template switching.

Chromosome 7 aberrations in a young girl with myelodysplasia and hepatoblastoma: an unusual association

We report a 30-month-old female with intrauterine growth retardation, postnatal failure to thrive, pancytopoenia and myelodysplasia with monosomy 7 in the marrow. The child succumbed to overwhelming sepsis, following a bone marrow transplant to facilitate chemotherapy for metastatic hepatoblastoma--a tumour that has not been previously reported in myelodysplasia syndromes. Cytogenetic, molecular and microarray analysis of peripheral blood, skin fibroblasts and bone marrow revealed unusual results, suggestive of somatic chromosome instability. A normal peripheral blood karyotype was documented in infancy. Monosomy 7 was found in the bone marrow. Molecular (microsatellite marker) results for a later peripheral blood specimen were suggestive of partial maternal isodisomy 7q, and this was supported by microarray data on single-nucleotide polymorphisms. Microarray data on gene copy number, collected for the same blood specimen, indicated cryptic mosaicism for the monosomy 7 cell line, with the monosomic line lacking the paternal copy. In fibroblasts, cytogenetic data showed mosaic partial trisomy for distal 7p.

The effectiveness of high–resolution-comparative genomic hybridization in detecting the most common chromosomal abnormalities in pediatric myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a diverse and heterogeneous group of clonal and potentially malignant bone marrow (BM) disorders. The up-to-date used criteria are the ones proposed by the French-American-British (FAB) group in 1982, the World Health Organization (WHO) classification, and a new, recently presented classification: categories cytology cytogenetics (CCC) system or 2003 WHO classification scheme. Comparative genomic hybridization (CGH) is a technique that permits the detection of chromosomal imbalances within a "one step" analysis. In our study, we present 5 cases of MDS and 4 cases of acute myelogenous leukemia (AML). By means of high-resolution CGH (HR-CGH) analysis, we were able to detect DNA copy number alterations in 8 out of 9 samples. The changes were as follows: -7, -Y, del(5)(q33q34), del(11)(q22q24), del(5p), del(9)(q21q31), nullisomy X, and +8. In 5/9 cases the HR-CGH data were highly comparable with conventional cytogenetics and interphase/metaphase fluorescence in situ hybridization findings. Additionally, in 3 BM samples the HR-CGH revealed the presence of changes that had not been detected by conventional cytogenetics: del(5p), del(5)(q33q34), del(9)(q21q31), and nullisomy X. The high effectiveness, specificity, and sensitivity of this method are in concordance with the conventional cytogenetics and FISH findings and the ability to detect new changes.

The myelodysplastic syndrome(s): a perspective and review highlighting current controversies

The myelodysplastic syndrome (MDS) includes a diverse group of clonal and potentially malignant bone marrow disorders characterized by ineffective and inadequate hematopoiesis. The presumed source of MDS is a genetically injured early marrow progenitor cell or pluripotential hematopoietic stem cell. The blood dyscrasias that fall under the broad diagnostic rubric of MDS appear to be quite heterogeneous, which has made it very difficult to construct a coherent, universally applicable MDS classification scheme. A recent re-classification proposal sponsored by the World Health Organization (WHO) has engendered considerable controversy. Although the precise incidence of MDS is uncertain, it has become clear that MDS is at least as common as acute myelogenous leukemia (AML). There is considerable overlap between these two conditions, and the former often segues into the latter; indeed, the distinction between AML and MDS can be murky, and some have argued that the current definitions are arbitrary. Despite the discovery of several tantalizing pathophysiological clues, the basic biology of MDS is incompletely understood. Treatment at present is generally frustrating and ineffective, and except for the small subset of patients who exhibit mild marrow dysfunction and low-risk cytogenetic lesions, the overall prognosis remains rather grim. In this narrative review, we highlight recent developments and controversies within the context of current knowledge about this mysterious and fascinating cluster of bone marrow failure states.

Subvalvular pulmonary stenosis, demyelination and myelodysplasia with monosomy 7

We report a 23-year-old male with subvalvular pulmonary stenosis (PS) presenting with concurrent acute demyelinating neuropathy and myelodysplasia with monosomy 7. There was no stigmata of Noonan syndrome or neurofibromatosis, nor any family history of cardiac or hematologic disorders. There are 40 reported pediatric cases of Noonan syndrome with subvalvular PS that developed leukemia, over two-thirds with monosomy 7. There is also a genetic overlap between Noonan syndrome and neurofibromatosis, which is also closely associated with demyelination and leukemia. The importance of recognition of rare clinical syndromes that may predispose to leukemia is discussed.

Childhood myeloid leukaemias

Childhood myeloid leukaemias are a diverse collection of conditions. Although many are also seen in adults, some are peculiar to childhood. In childhood AML, as in adults, cytogenetic abnormalities are associated with specific clinical features and define prognostic groups. In infants under 1 year with AML, the incidence of 11q23 abnormalities is particularly high. The finding of identical 11q23 breakpoints in infant leukaemia as in therapy-related leukaemias suggests a role for in utero exposure to topoisomerase II inhibitors. There are a number of constitutional disorders that predispose children to develop AML, usually with a preceding myelodysplastic phase. Monosomy (or deletion of the long arm) of chromosome 7 is the most frequent chromosome abnormality in the bone marrow of such patients. Abnormalities of chromosome 7 are also common cytogenetic findings in all morphological subgroups of childhood myelodysplasia, either as a primary abnormality or associated with disease progression.

Evaluation of children with myelodysplastic syndrome: importance of extramedullary disease as a presenting symptom

Thirty-three children diagnosed with primary myelodysplastic syndrome (MDS) in a single institution over an 8 year period were evaluated with special emphasis on children who presented with extramedullary disease (EMD). EMD was present at diagnosis in 12 (36%) of the 33 children with MDS. Three patients with juvenile myelomonocytic leukemia (JMML) and 2 patients with chronic myelomonocytic leukemia (CMML) presented with pleural effusion. Pericardial effusion was present in 3 of these patients, two of whom also had thrombosis. Pyoderma gangrenosum, relapsing polychondritis were the initial findings in another two cases with JMML. Lymphadenopathy (n=1), gingival hypertrophy (n=2), orbital granulocytic sarcoma (n=1) and spinal mass (n=1) were the presenting findings in 5 patients with refractory anemia with excess of blasts in transformation. Since high-dose methylprednisolone (HDMP, 20-30 mg/kg/day) has been shown to induce differentiation and apoptosis of myeloid leukemic cells in children with different morphological subtypes of acute myeloid leukemia in vivo and in vitro, 25 children with de novo MDS were treated with combined HDMP and cytotoxic chemotherapy. Dramatic improvement of EMD and decrease in blast cells both in the peripheral blood and bone marrow were obtained following administration of short-course HDMP treatment alone as observed in children with AML. HDMP, combined with low-dose cytosine arabinoside and mitoxantrone were used for the remission induction. Remission was achieved in 8 (80%) of 10 children who presented with EMD and in 9 (60%) of 15 children without EMD. Long-term remission (>6 years) was obtained in 4 (two with JMML and two with CMML), three of whom presented with EMD. In conclusion EMD can be a presenting finding in childhood MDS as observed in adults. In addition, the beneficial effect of HDMP combined with more intensive chemotherapy should be explored as alternative therapy in children with MDS not suitable for bone marrow transplantation.

Chromosomal aberrations in Bloom syndrome patients with myeloid malignancies

Bloom syndrome (BS) predisposes affected individuals to a wide variety of neoplasms including hematological malignancies. Thus far, cytogenetic findings in hematological neoplasms have been reported in only a few BS patients. We present the karyotypic findings in a BS patient diagnosed with acute myeloid leukemia (AML), FAB subtype M1, and a review of the literature, showing the preferential occurrence of total or partial loss of chromosome 7 in BS patients with AML or myelodysplastic syndromes (MDS).