Natural history of transient myeloproliferative disorder clinically diagnosed in Down syndrome neonates: a report from the Children's Oncology Group Study A2971

Two patients of trisomy 21 with transient abnormal myelopoiesis with hypereosinophilia without blasts in peripheral blood smears

Clinical diagnosis of transient abnormal myelopoiesis (TAM) relies on the detection of characteristic blasts and leukocytosis in peripheral blood. We report two patients of trisomy 21 with TAM with hypereosinophilia, who had neither circulating blasts nor leukocytosis. Genetic testing of polymorphonuclear leukocytes isolated from whole blood revealed heterozygous mutations in GATA1, suggesting that the mutations were harbored in increased eosinophils. Both patients had direct hyperbilirubinemia and one died of liver fibrosis. Our findings emphasize the importance of screening for GATA1 mutations in neonatal infants with Down syndrome and hypereosinophilia even if blasts are not detected in peripheral blood smears.

Neonatal Leukemia

Neonates are at risk for 3 major forms of leukemia in the first year of life: acute leukemia, juvenile myelomonocytic leukemia, and transient abnormal myelopoiesis associated with Down syndrome. These disorders are rare but generate interest due to aggressive clinical presentation, suboptimal response to current therapies, and fascinating biology. Each can arise as a result of unique constitutional and acquired genetic events. Genetic insights are pointing the way toward novel therapeutic approaches. This article reviews key epidemiologic, clinical, and molecular features of neonatal leukemias, focusing on risk stratification, treatment, and strategies for developing novel molecularly targeted approaches to improve future outcomes.

A Case of Novel GATA-1 Mutation-positive Transient Abnormal Myelopoiesis With Life-threatening Complications in a Neonate With Down Syndrome

Transient abnormal myelopoiesis is a transient myeloproliferative disorder seen in ∼15% to 20% of infants with Down syndrome. These infants are usually asymptomatic, requiring only monitoring, but they can have variable severity of symptoms up to multisystemic dysfunction requiring chemotherapy. GATA-1 somatic mutations acquired in utero are pathognomic of this entity and present nearly in all cases. Herein, we present a case of Down syndrome in a neonate who presented within her first week of life with life-threatening features of transient abnormal myelopoiesis requiring chemotherapy support. In addition, next-generation sequencing revealed a small mutant clone (8%) positive for a novel frameshift GATA-1 mutation.

Acute Leukemia in Infants

PURPOSE OF THE REVIEW

Infant leukemia is a rare, distinct subgroup of pediatric acute leukemias diagnosed in children under 1 year of age and characterized by unique, aggressive biology. Here, we review its clinical presentation, underlying molecular biology, current treatment strategies, and novel therapeutic approaches.

RECENT FINDINGS

Infant leukemias are associated with high-risk molecular features and high rates of chemotherapy resistance. International collaborative clinical trials have led to better understanding of the underlying molecular biology, refined risk-based stratification, and investigated the use of hematopoietic stem cell transplantation. However, intensification of chemotherapy has failed to improve outcomes, and current regimens are associated with significant treatment-related and long-term toxicities. Infants with leukemia remain a challenging group to treat. We must continue collaborative efforts to move beyond traditional cytotoxic chemotherapy, incorporate molecularly targeted strategies and immunotherapy, and increase access to clinical trials to improve outcomes for this high-risk group of patients.

Gain of chromosome 21 in hematological malignancies: lessons from studying leukemia in children with Down syndrome

Structural and numerical alterations of chromosome 21 are extremely common in hematological malignancies. While the functional impact of chimeric transcripts from fused chromosome 21 genes such as TEL-AML1, AML1-ETO, or FUS-ERG have been extensively studied, the role of gain of chromosome 21 remains largely unknown. Gain of chromosome 21 is a frequently occurring aberration in several types of acute leukemia and can be found in up to 35% of cases. Children with Down syndrome (DS), who harbor constitutive trisomy 21, highlight the link between gain of chromosome 21 and leukemogenesis, with an increased risk of developing acute leukemia compared with other children. Clinical outcomes for DS-associated leukemia have improved over the years through the development of uniform treatment protocols facilitated by international cooperative groups. The genetic landscape has also recently been characterized, providing an insight into the molecular pathogenesis underlying DS-associated leukemia. These studies emphasize the key role of trisomy 21 in priming a developmental stage and cellular context susceptible to transformation, and have unveiled its cooperative function with additional genetic events that occur during leukemia progression. Here, using DS-leukemia as a paradigm, we aim to integrate our current understanding of the role of trisomy 21, of critical dosage-sensitive chromosome 21 genes, and of associated mechanisms underlying the development of hematological malignancies. This review will pave the way for future investigations on the broad impact of gain of chromosome 21 in hematological cancer, with a view to discovering new vulnerabilities and develop novel targeted therapies to improve long term outcomes for DS and non-DS patients.

Factors influencing platelet normalization of transient abnormal myelopoiesis

BACKGROUND

Abnormal blood cell counts are characteristic of patients with Down syndrome and transient abnormal myelopoiesis (TAM). Although some patients with TAM experience prolonged anemia or thrombocytopenia, hematological factors predicting blood cell count recovery have not been reported yet. The aim of this study was to investigate the factors influencing platelet normalization in TAM.

METHODS

A retrospective review of the medical records of 21 patients with TAM admitted to the neonatal intensive care unit at Kanagawa Children's Medical Center between January 2007 and October 2014 was undertaken.

RESULTS

In the 16 of 21 patients (76%) experiencing transient thrombocytopenia, a large number of blasts at diagnosis was found to be significantly associated with late platelet recovery (R = 0.669, P < 0.05), and higher platelet counts at diagnosis were significantly associated with later recovery (R = 0.719, P < 0.01). Indeed, a strong positive correlation between blast and platelet counts at diagnosis was found (R = 0.730, P < 0.01).

CONCLUSIONS

Our data suggest that high platelet counts at TAM diagnosis might reflect abnormal thrombocyte production from blasts. Thus, physicians should be aware of the possibility of prolonged thrombocytopenia in patients with TAM who exhibit a high platelet and/or blast count at diagnosis.

Treatments for children and adolescents with AML

In recent decades, survival rates for childhood acute myeloid leukemia have remarkably improved, owing to chemotherapy intensification, allogeneic hematopoietic stem cell transplantation, and improved supportive care. Furthermore, treatment protocols have evolved and are currently better matched to prognostic factors and treatment responses. Recently, new molecular prognostic factors were discovered via leukemia genomic studies. Moreover, new tumor subtypes with independent gene expression profiles have been characterized. To broaden the therapeutic options for patients with poor prognoses, therapies that target specific candidate mutations are being identified. Additionally, new drugs are undergoing clinical trials, and immunotherapy is attracting significant interest as a treatment option for recurrent or refractory childhood acute myeloid leukemia.

Complete blood count differences in a cohort of Down syndrome neonates with transient abnormal myelopoiesis screened for GATA1 pathogenic variants

Transient abnormal myelopoiesis (TAM) raises the risk for acute myeloid leukemia of Down syndrome (DS) (ML-DS), and both are related to GATA1 pathogenic variants. Here, we analyzed which findings on complete blood count (CBC) are associated with TAM in a cohort of neonates with DS screened for GATA1 pathogenic variants. The CBCs were compared among 70 newborns with DS, including 16 patients (22.9%) with TAM (cases), and 54 patients (77.1%) without TAM (controls). TAM was defined as peripheral circulating blasts (PCBs) ≥ 1%. PCR and direct sequencing were used to screen DNA samples from peripheral blood for GATA1 exon 2 mutations. Multivariate logistic regression analyses determined that the mean count of lymphocytes was significantly higher in DS infants with TAM (p = .035) and that lymphocytosis confers a risk for TAM (adjusted odds ratio = 7.23, 95% confidence intervals: 2.02-25.92). Pathogenic variants of GATA1 were identified in 2 of 70 analyzed DS neonates (2.9%), of which one had ML-DS and another had an asymptomatic TAM. Among those DS infants with TAM, the GATA1 pathogenic variant detection was 12.5%. Our results indicated that lymphocytosis is associated with TAM in neonates with DS. However, since not all infants with an abnormal CBC had TAM, and not all infants with TAM had GATA1 pathogenic variants, we emphasize that only the search for GATA1 pathogenic variants allows the proper identification of the subgroup of DS infants with a real increasing in risk for ML-DS.

Retrospective Analysis of the Treatment Outcome in Myeloid Leukemia of Down Syndrome in Polish Pediatric Leukemia and Lymphoma Study Group From 2005 to 2019

Background: Children with Down syndrome (DS) have increased risk of myeloid leukemia (ML), but specific treatment protocols ensure excellent outcome. This study was a retrospective analysis of the treatment results and genetic characteristics of ML of DS (ML-DS) in Poland from 2005 to 2019. Methods: All 54 patients with ML-DS registered in the Polish Pediatric Leukemia and Lymphoma Study Group in analyzed period were enrolled to the study. There were 34 children treated with Acute Myeloid Leukemia-Berlin-Frankfurt-Munster 2004 Interim Protocol (group I) and 20 patients treated with ML-DS 2006 Protocol (group II). In the first protocol, there was reduction of the antracyclines doses and intrathecal treatment for ML-DS compared to non-DS patients. In the second protocol, further reduction of the treatment was introduced (omission of etoposide in the last cycle, no maintenance therapy). Results: Probabilities of 5-year overall survival (OS), event-free survival (EFS), and relapse-free survival in the whole analyzed group were 0.85 ± 0.05, 0.83 ± 0.05, and 0.97 ± 0.03, respectively. No significant differences were found between two protocols in the terms of OS and EFS (0.79 ± 0.07 vs. 0.95 ± 0.05, p = 0.14, and 0.76 ± 0.07 vs. 0.95 ± 0.05, p = 0.12, respectively). All deaths were caused by the treatment-related toxicities. Reduction of the treatment-related mortality was noticed (20% in group I and 5% in group II). The only one relapse in the whole cohort occurred in the patient from group I, older than 4 years, without GATA1 gene mutation. He was treated successfully with IdaFLA cycle followed by hematopoietic stem cell transplantation from matched sibling donor. No significant prognostic factor was found in the study group probably due to low number of patients in the subgroups. Conclusions: The study confirms that the reduced intensity protocols are very effective in ML-DS patients. The only cause of deaths was toxicities; however, systematic decrease of the treatment-related mortality was noticed.

Clinical, cytogenetic, and molecular analyses of 17 neonates with transient abnormal myelopoiesis and nonconstitutional trisomy 21

BACKGROUND

Transient abnormal myelopoiesis (TAM) is a unique myeloproliferative disorder that occurs in neonates with constitutional trisomy 21/Down syndrome (DS). Although TAM also develops in neonates without constitutional trisomy 21, the clinical, cytogenetic, and molecular characteristics of those patients are not fully understood.

PROCEDURE

We retrospectively evaluated the clinical and cytogenetic findings and GATA1 mutation status of 17 neonates with TAM and nonconstitutional trisomy 21 tested for GATA1 mutations at our institute, and compared the findings with those of 64 neonates with TAM and constitutional trisomy 21/DS.

RESULTS

DS clinical features were observed in five of the 17 (29%) patients. In all patients, both trisomy 21 and GATA1 mutations were detected in diagnostic samples. Over a median follow-up of 33 (range, 0-139) months, early death (< 6 months of age) occurred in four patients (24%). Overall and event-free survivals were not significantly different between the patients with TAM and nonconstitutional trisomy 21 and those with TAM and constitutional trisomy 21/DS (five-year overall survival: 76% ± 10% vs 53% ± 13%, P = 0.40; five-year event-free survival: 55% ± 13% vs 48% ± 12%, P = 0.90). The five-year cumulative incidence of progression to myeloid leukemia of DS was also similar between the groups (21% vs 24%, P = 0.80).

CONCLUSIONS

Patients with TAM and nonconstitutional trisomy 21 exhibited similar biology and outcomes to those with TAM and constitutional trisomy 21/DS. The possibility of TAM should be considered even in phenotypically normal neonates with TAM symptoms, for appropriate management.

Pediatric acute myeloid leukemia: updates on biology, risk stratification, and therapy

PURPOSE OF REVIEW

Despite advances in therapy over the past decades, overall survival for children with acute myeloid leukemia (AML) has not exceeded 70%. In this review, we highlight recent insights into risk stratification for patients with pediatric AML and discuss data driving current and developing therapeutic approaches.

RECENT FINDINGS

Advances in cytogenetics and molecular profiling, as well as improvements in detection of minimal residual disease after induction therapy, have informed risk stratification, which now relies heavily on these elements. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. However, recent trials focus on limiting treatment-related toxicity through the identification of low-risk subsets who can safely receive fewer cycles of chemotherapy, allocation of hematopoietic stem-cell transplant to only high-risk patients and optimization of infectious and cardioprotective supportive care.

SUMMARY

Further incorporation of genomic and molecular data in pediatric AML will allow for additional refinements in risk stratification to enable the tailoring of treatment intensity. These data will also dictate the incorporation of molecularly targeted therapeutics into frontline treatment in the hope of improving survival while decreasing treatment-related toxicity.

Neonatal hemochromatosis in a newborn with Down syndrome

Background: Neonatal hemochromatosis (NH) is a cause of neonatal/pediatric acute liver failure. Liver dysfunction/failure in Down syndrome had been described in relation to increased susceptibility to infection and transient myeloproliferative disease (TMD). The occurrence of NH in Down syndrome is described in only a few case reports. Material and methods: A complete autopsy have been performed in a 79-day-old infant with severe liver dysfunction. TMD was suspected antemortem following a report of peripheral blood leukocytosis with 14% atypical cells. Results: The complete autopsy revealed NH-phenotype to be the cause of liver dysfunction and subsequent death. Conclusion: Though TMD is a common cause of liver dysfunction in Down syndrome, NH should also be considered in its differential.

GATA1 and cooperating mutations in myeloid leukaemia of Down syndrome

Myeloid leukaemia of Down syndrome (ML-DS) is an acute megakaryoblastic/erythroid leukaemia uniquely found in children with Down syndrome (constitutive trisomy 21). It has a unique clinical course, being preceded by a pre-leukaemic condition known as transient abnormal myelopoiesis (TAM), and provides an excellent model to study multistep leukaemogenesis. Both TAM and ML-DS blasts carry acquired N-terminal truncating mutations in the erythro-megakaryocytic transcription factor GATA1. These result in exclusive production of a shorter isoform (GATA1s). The majority of TAM cases resolve spontaneously without the need for treatment; however, around 10% acquire additional cooperating mutations and transform to leukaemia, with differentiation block and clinically significant cytopenias. Transformation is driven by the acquisition of additional mutation(s), which cooperate with GATA1s to perturb normal haematopoiesis.

Two Novel GATA1 Mutations in Transient Abnormal Myelopoiesis of Thai Neonates with Down Syndrome

Children with Down syndrome (DS) are 150 times more likely to develop acute myeloid leukemia (ML-DS), compared with those without. One risk factor is transient abnormal myelopoiesis (TAM). Somatic truncating GATA1 mutations are found in most TAM patients and are markers for future ML-DS. We identified two novel frameshift mutations in our seven newborns with DS and TAM: a heterozygous mutation of 17 nucleotide duplication (c.154_170 dup) and a heterozygous 9-nucleotide deletion combined with a 2-nucleotide insertion (c.150_158delins CT). Both mutations introduced a truncated GATA1 protein. Thus, neonates with DS and TAM require frequent ML-DS monitoring.

Neonatal vesiculopustular eruption in Down syndrome and transient myeloproliferative disorder: A case report and review of the literature

Transient myeloproliferative disorder (TMD) is a spontaneously resolving clonal myeloid proliferation characterized by circulating megakaryoblasts in the peripheral blood that is restricted to neonates with Down syndrome (DS) or those with trisomy 21 mosaicism. Cutaneous manifestations of TMD are observed in only 5% of affected neonates and present as a diffuse eruption of erythematous, crusted papules, papulovesicles, and pustules, often with prominent and initial facial involvement. We describe the case of a male infant with DS and TMD, associated with a vesiculopustular eruption, which appeared on day 36 of life, and review previous cases.

Mechanisms of Progression of Myeloid Preleukemia to Transformed Myeloid Leukemia in Children with Down Syndrome

Myeloid leukemia in Down syndrome (ML-DS) clonally evolves from transient abnormal myelopoiesis (TAM), a preleukemic condition in DS newborns. To define mechanisms of leukemic transformation, we combined exome and targeted resequencing of 111 TAM and 141 ML-DS samples with functional analyses. TAM requires trisomy 21 and truncating mutations in GATA1; additional TAM variants are usually not pathogenic. By contrast, in ML-DS, clonal and subclonal variants are functionally required. We identified a recurrent and oncogenic hotspot gain-of-function mutation in myeloid cytokine receptor CSF2RB. By a multiplex CRISPR/Cas9 screen in an in vivo murine TAM model, we tested loss-of-function of 22 recurrently mutated ML-DS genes. Loss of 18 different genes produced leukemias that phenotypically, genetically, and transcriptionally mirrored ML-DS.

Transient leukemia of Down syndrome

Childhood leukemia is mostly a "developmental accident" during fetal hematopoiesis and may require multiple prenatal and postnatal "hits". The World Health Organization defines transient leukemia of Down syndrome (DS) as increased peripheral blood blasts in neonates with DS and classifies this type of leukemia as a separate entity. Although it was shown that DS predisposes children to myeloid leukemia, neither the nature of the predisposition nor the associated genetic lesions have been defined. Acute myeloid leukemia of DS is a unique disease characterized by a long pre-leukemic, myelodysplastic phase, unusual chromosomal findings and a high cure rate. In the present manuscript, we present a comprehensive review of the literature about clinical and biological findings of transient leukemia of DS (TL-DS) and link them with the genetic discoveries in the field. We address the manuscript to the pediatric generalist and especially to the next generation of pediatric hematologists.

Changes in the peripheral blood cell count in pediatric patients with Down syndrome

Objectives

Down syndrome (DS) is associated with multiple complications, including a high risk of leukemia and thyroid dysfunction. This clinical study aimed to examine the complete blood cell count in patients with DS without leukemia or transient abnormal myelopoiesis. We also aimed to evaluate the effect of thyroid dysfunction on hematological anomalies in DS.

Methods

We analyzed the peripheral blood cell count in 23 pediatric patients with DS with and without thyroid dysfunction and in 17 pediatric patients without DS with thyroid dysfunction.

Results

Patients with DS showed greater neutrophilia and lymphopenia than did patients with DS and hypothyroidism and patients with hypothyroidism. Surprisingly, patients with DS showed a significant degree of eosinopenia in the peripheral blood. Interestingly, hypothyroidism had an attenuating effect on different lineages in the complete blood count. However, these anomalies were specific for DS.

Conclusions

Our clinical findings support previous data on DS-associated changes in the complete blood count. Our study also shows novel alterations in the complete blood count in leukemia-free patients with DS in association with hypothyroidism. The attenuating effect of thyroid dysfunction on changes in different lineages in the context of DS is novel and deserves further analysis in larger studies.

Placental Pathology in Down Syndrome-Associated Transient Abnormal Myelopoiesis

Transient abnormal myelopoiesis is a hematopoietic disorder that occurs in up to 10% of neonates with Down syndrome. It is characterized by leukocytosis and the presence of circulating blast cells harboring truncating GATA1 mutations with variable multiorgan system involvement. Placental involvement of transient abnormal myelopoiesis is infrequently described. Placental examination and identifying features related to transient abnormal myelopoiesis could be one of the early, if not the only, means of diagnosis of this condition in affected stillbirths, premature infants, and a subset of asymptomatic neonates. This article provides an overview of the placental pathology in transient abnormal myelopoiesis with review of the literature, and also discusses the important differential diagnoses.

Low-dose cytarabine to prevent myeloid leukemia in children with Down syndrome: TMD Prevention 2007 study

Approximately 5% to 10% of children with Down syndrome (DS) are diagnosed with transient myeloproliferative disorder (TMD). Approximately 20% of these patients die within 6 months (early death), and another 20% to 30% progress to myeloid leukemia (ML-DS) within their first 4 years of life. The aim of the multicenter, nonrandomized, historically controlled TMD Prevention 2007 trial was to evaluate the impact of low-dose cytarabine treatment on survival and prevention of ML-DS in patients with TMD. Patients received cytarabine (1.5 mg/kg for 7 days) in case of TMD-related symptoms at diagnosis (high white blood cell count, ascites, liver dysfunction, hydrops fetalis) or detection of minimal residual disease (MRD) 8 weeks after diagnosis. The 5-year probability of event-free and overall survival of 102 enrolled TMD patients was 72 ± 5% and 91 ± 3%, respectively. In patients eligible for treatment because of symptoms (n = 43), we observed a significantly lower cumulative incidence (CI) of early death as compared with symptomatic patients in the historical control (n = 45) (12 ± 5% vs 33 ± 7%, P_Gray = .02). None of the asymptomatic patients in the current study suffered early death. However, the treatment of symptomatic or MRD-positive patients did not result in a significantly lower CI of ML-DS (25 ± 7% [treated] vs 14 ± 7% [untreated], P_Gray = .34 [per protocol analysis]; historical control: 22 ± 4%, P_Gray = .55). Thus, low-dose cytarabine treatment helped to reduce TMD-related mortality when compared with the historical control but was insufficient to prevent progression to ML-DS. This trial was registered at EudraCT as #2006-002962-20.

Recent advances in the understanding of transient abnormal myelopoiesis in Down syndrome

Neonates with Down syndrome (DS) have a propensity to develop the unique myeloproliferative disorder, transient abnormal myelopoiesis (TAM). TAM usually resolves spontaneously in ≤3 months, but approximately 10% of patients with TAM die from hepatic or multi-organ failure. After remission, 20% of patients with TAM develop acute myeloid leukemia associated with Down syndrome (ML-DS). Blasts in both TAM and ML-DS have trisomy 21 and GATA binding protein 1 (GATA1) mutations. Recent studies have shown that infants with DS and no clinical signs of TAM or increases in peripheral blood blasts can have minor clones carrying GATA1 mutations, referred to as silent TAM. Low-dose cytarabine can improve the outcomes of patients with TAM and high white blood cell count. A number of studies using fetal liver cells, mouse models, or induced pluripotent stem cells have elucidated the roles of trisomy 21 and GATA1 mutations in the development of TAM. Next-generation sequencing of TAM and ML-DS patient samples identified additional mutations in genes involved in epigenetic regulation. Xenograft models of TAM demonstrate the genetic heterogeneity of TAM blasts and mimic the process of clonal selection and expansion of TAM clones that leads to ML-DS. DNA methylation analysis suggests that epigenetic dysregulation may be involved in the progression from TAM to ML-DS. Unraveling the mechanisms underlying leukemogenesis and identification of factors that predict progression to leukemia could assist in development of strategies to prevent progression to ML-DS. Investigation of TAM, a unique pre-leukemic condition, will continue to strongly influence basic and clinical research into the development of hematological malignancies.

Fetal cerebral hemorrhage due to X-linked GATA1 gene mutation

We report a multiplex family with a GATA1 gene mutation responsible for a massive fetal cerebral hemorrhage occurring at 36 weeks. Two other stillbirth cousins presented with fetal hydrops and congenital hemochromatosis' phenotype at 37 and 12 weeks of gestation. Molecular screening revealed the presence of a c.613G>A pathogenic allelic variation in exon 4 of GATA1 gene in the 3 male siblings and their carrier mothers. The diagnosis of a GATA1 gene mutation may be suspected in cases of male fetuses with intracerebral bleeding, particularly if a history of prior fetal loss(es) and mild maternal thrombocytopenia are also present.

A Rare Case of Spontaneous Remission of Terminal Deoxynucleotidyl Transferase Negative B-acute Lymphoblastic Leukemia

Spontaneous remission of untreated pediatric leukemia is an extremely rare occurrence. The underlying mechanism may be because of an immune-mediated process or increased cortisol production during stress or infection. We describe a rare case of terminal deoxynucleotidyl transferase negative B-acute lymphoblastic leukemia with concurrent infection that went into remission without treatment with chemotherapy or corticosteroids. Though B-acute lymphoblastic leukemia can rarely go into spontaneous remission, these patients require close follow-up as most patients will eventually develop recurrence.

Combinations of chromosome transfer and genome editing for the development of cell/animal models of human disease and humanized animal models

Chromosome transfer technology, including chromosome modification, enables the introduction of Mb-sized or multiple genes to desired cells or animals. This technology has allowed innovative developments to be made for models of human disease and humanized animals, including Down syndrome model mice and humanized transchromosomic (Tc) immunoglobulin mice. Genome editing techniques are developing rapidly, and permit modifications such as gene knockout and knockin to be performed in various cell lines and animals. This review summarizes chromosome transfer-related technologies and the combined technologies of chromosome transfer and genome editing mainly for the production of cell/animal models of human disease and humanized animal models. Specifically, these include: (1) chromosome modification with genome editing in Chinese hamster ovary cells and mouse A9 cells for efficient transfer to desired cell types; (2) single-nucleotide polymorphism modification in humanized Tc mice with genome editing; and (3) generation of a disease model of Down syndrome-associated hematopoiesis abnormalities by the transfer of human chromosome 21 to normal human embryonic stem cells and the induction of mutation(s) in the endogenous gene(s) with genome editing. These combinations of chromosome transfer and genome editing open up new avenues for drug development and therapy as well as for basic research.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology

CONTEXT

- A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia.

OBJECTIVE

- To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage.

DESIGN

- The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus.

RESULTS

- Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported.

CONCLUSIONS

- The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Flow Cytometry in Pediatric Hematopoietic Malignancies

Utility of flow cytometry in the evaluation of pediatric hematopoietic neoplasms and the differences from adult hematopoietic neoplasms are discussed in this review. Distinction of hematogones from B-lymphoblasts, detection of residual/relapsed disease after novel targeted therapies, and evaluation of pediatric myeloid neoplasms are discussed.

Familial Myelodysplastic/Acute Leukemia Syndromes-Myeloid Neoplasms with Germline Predisposition

Although most cases of myeloid neoplasms are sporadic, a small subset has been associated with germline mutations. The 2016 revision of the World Health Organization classification included these cases in a myeloid neoplasm group with a predisposing germline mutational background. These patients must have a different management and their families should get genetic counseling. Cases identification and outline of the major known syndromes characteristics will be discussed in this text.

The under reporting of recruitment strategies in research with children with life-threatening illnesses: A systematic review

BACKGROUND

Researchers report difficulties in conducting research with children and young people with life-limiting conditions or life-threatening illnesses and their families. Recruitment is challenged by barriers including ethical, logistical and clinical considerations.

AIM

To explore how children and young people (aged 0-25 years) with life-limiting conditions or life-threatening illnesses and their families were identified, invited and consented to research published in the last 5 years.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE, PsycINFO, Web of Science, Sciences Citation Index and SCOPUS were searched for original English language research published between 2009 and 2014, recruiting children and young people with life-limiting conditions or life-threatening illness and their families.

RESULTS

A total of 215 studies - 152 qualitative, 54 quantitative and 9 mixed methods - were included. Limited recruitment information but a range of strategies and difficulties were provided. The proportion of eligible participants from those screened could not be calculated in 80% of studies. Recruitment rates could not be calculated in 77%. A total of 31% of studies recruited less than 50% of eligible participants. Reasons given for non-invitation included missing clinical or contact data, or clinician judgements of participant unsuitability. Reasons for non-participation included lack of interest and participants' perceptions of potential burdens.

CONCLUSION

All stages of recruitment were under reported. Transparency in reporting of participant identification, invitation and consent is needed to enable researchers to understand research implications, bias risk and to whom results apply. Research is needed to explore why consenting participants decide to take part or not and their experiences of research recruitment.

Resolution of liver disease in transient abnormal myelopoiesis with fish oil emulsion

Neonates with Down syndrome are at risk of developing transient abnormal myelopoiesis (TAM), which is characterized by transient clonal myeloproliferation of the blast cells. TAM can resolve spontaneously, but some patients die at an early age due to organ failure. Liver fibrosis in TAM is a life-threatening condition, but treatment options have not yet been established. Here, we report on the case of an infant with TAM complicated by liver disease, whose hyperbilirubinemia was successfully ameliorated with omega-3 fatty acid (ω3FA) lipid emulsion. Timely ω3FA lipid emulsion may be a feasible treatment for liver disease in TAM before serious liver damage develops.

Transient Abnormal Myelopoiesis: A Varied Spectrum of Clinical Presentation

Transient myeloproliferative disorder (TMD) is a condition seen almost exclusively in newborns with Down syndrome (DS). It can have a spectrum of clinical presentation ranging from being asymptomatic with incidental detection to a stormy course and fatal outcome. We describe three cases of TMD having different clinical presentation, course, complications and outcome. All but one had Down’s phenotype; one of them had a severe disease with tumor lysis syndrome and died of liver failure, while the other one had pericardial effusion and cardiac failure but survived. The third patient had a very benign course of illness requiring only supportive care. Newborns with DS should be screened for TMD by a complete blood count during their first month of life, irrespective of symptoms. With increasing knowledge about the natural history and management guidelines, the prognosis of this rare and unique entity has improved in recent years.

GATA factor mutations in hematologic disease

GATA family proteins play essential roles in development of many cell types, including hematopoietic, cardiac, and endodermal lineages. The first three factors, GATAs 1, 2, and 3, are essential for normal hematopoiesis, and their mutations are responsible for a variety of blood disorders. Acquired and inherited GATA1 mutations contribute to Diamond-Blackfan anemia, acute megakaryoblastic leukemia, transient myeloproliferative disorder, and a group of related congenital dyserythropoietic anemias with thrombocytopenia. Conversely, germ line mutations in GATA2 are associated with GATA2 deficiency syndrome, whereas acquired mutations are seen in myelodysplastic syndrome, acute myeloid leukemia, and in blast crisis transformation of chronic myeloid leukemia. The fact that mutations in these genes are commonly seen in blood disorders underscores their critical roles and highlights the need to develop targeted therapies for transcription factors. This review focuses on hematopoietic disorders that are associated with mutations in two prominent GATA family members, GATA1 and GATA2.

Successful Liver Transplantation for Transient Abnormal Myelopoiesis-Associated Liver Failure

Infants with Down syndrome (DS) are at risk of developing a transient abnormal myelopoiesis (TAM). TAM occasionally involves liver fibrosis, which can be fatal. The management of liver disease in TAM has not yet been established and is mainly supportive. We report an infant with DS and TAM who developed end-stage liver failure. Liver dysfunction progressed even after blast cells disappeared from the circulation. He underwent a living-donor liver transplantation at 56 days of life without surgical complications. The explanted liver showed atrophy and severe fibrosis without leukemic cell infiltration. The posttransplant course was favorable with no hematological abnormality. He is doing well 8 months after transplantation. To the best of our knowledge, this report is the first showing that liver transplantation might be a treatment option for TAM-related liver failure.

Distinct GATA1 Point Mutations in Monozygotic Twins With Down Syndrome and Transient Abnormal Myelopoiesis From a Triplet Pregnancy: A Case Report and Review of Literature

OBJECTIVES

Down syndrome (DS)-associated transient abnormal myelopoiesis (TAM) or acute megakaryoblastic leukemia (AMKL) in monozygotic twins is exceedingly rare and has not been well characterized.

METHODS

We describe a unique case of monozygotic twins with simultaneous TAM from a triplet pregnancy at 34 weeks' gestation. Previously reported cases of TAM and DS-AMKL in monozygotic twins have been reviewed to compare with our cases. The current concept of a sequential multistep process in leukemogenesis and disease evolution of TAM into DS-AMKL through the collaboration among trisomy 21, GATA1, and other gene mutations is also reviewed.

RESULTS

Distinct GATA1 mutations are identified in our neonate twins with TAM from a triplet pregnancy, whereas precisely identical GATA1 mutations have been detected in all three monozygotic DS twins reported in the literature.

CONCLUSIONS

Identical GATA1 mutations in cases of monozygotic twins are likely derived from twin-twin transmission. Distinct GATA1 mutations identified in our neonate twins with TAM provide unequivocal evidence of independent intra-utero GATA1 mutations, a completely different mechanism of development of TAM in monozygotic twins from previously reported cases. Interaction of trisomy 21 and GATA1 mutation produces TAM, but additional gene mutations are required for TAM to transform into DS-AMKL.

Sometimes it is better to wait: First Italian case of a newborn with transient abnormal myelopoiesis and a favorable prognosis

Congenital leukemia is rare disease with an incidence of one to five cases per million births. Transient abnormal myelopoiesis (TAM), also called transient myeloproliferative disorder, is a pre-leukemia disorder that may occur in Down syndrome (DS) or non-DS infants. TAM may enter spontaneous remission; however, continual monitoring is required, as this disorder has been observed to develop into acute megakaryoblastic leukemia in 16–30% of cases. In the literature, 16 cases of TAM in non-DS infants have been reported. The case presented in the current study is, to the best of our knowledge, the first case of an Italian non-DS newborn presenting with clinical manifestations of acute leukemia at five days after birth, exhibiting a normal karyotype, trisomy 21 only in blast cells, and spontaneous remission. Chromosomal analyses on peripheral blood cells, bone marrow cells and dermal fibroblasts were conducted using a G-banding technique, and fluorescence in situ hybridization (FISH) was used to identify the critical regions of DS. Amplification of GATA binding protein 1 (GATA1) exon 2 genomic DNA was performed using polymerase chain reaction. Cytogenetic analysis of 50 peripheral blood cells and dermal fibroblasts from the patient revealed a normal karyotype: 46, XX. Conversely, cytogenetic analysis of the patient's bone marrow revealed an abnormal karyotype 47, XX+21. In order to investigate this result, FISH was performed, which identified the presence of three signals in 70% of the cells and two signals in 30% of bone marrow cells. GATA1 sequencing revealed the substitution of a single base (c.150delG) in exon 2. Seven months after the initial analysis, FISH and cytogenetic analyses of the stimulated/unstimulated peripheral blood cells and bone marrow cells were performed, revealing that each exhibited diploid signals, as observed in a normal karyotype.

Transient Abnormal Myelopoiesis and AML in Down Syndrome: an Update

Children with constitutional trisomy 21 (Down syndrome (DS)) have a unique predisposition to develop myeloid leukaemia of Down syndrome (ML-DS). This disorder is preceded by a transient neonatal preleukaemic syndrome, transient abnormal myelopoiesis (TAM). TAM and ML-DS are caused by co-operation between trisomy 21, which itself perturbs fetal haematopoiesis and acquired mutations in the key haematopoietic transcription factor gene GATA1. These mutations are found in almost one third of DS neonates and are frequently clinically and haematologcially 'silent'. While the majority of cases of TAM undergo spontaneous remission, ∼10 % will progress to ML-DS by acquiring transforming mutations in additional oncogenes. Recent advances in the unique biological, cytogenetic and molecular characteristics of TAM and ML-DS are reviewed here.

Progress and Prospects in Pediatric Leukemia

Pediatric leukemia is the single most common malignancy affecting children, representing up to 30% of all pediatric cancers. Dramatic improvements in survival for acute lymphoblastic leukemia (ALL) have taken place over the past 4 decades with outcomes approaching 90% in the latest studies. However, progress has been slower for myeloid leukemia and certain subgroups like infant ALL, adolescent/young adult ALL, and relapsed ALL. Recent advances include recognition of molecularly defined subgroups, which has ushered in precision medicine approaches. We discuss the current understanding of the biology of the various childhood leukemias, recent advances in research, and future challenges in this field.