High frequency of GATA2 mutations in patients with mild chronic neutropenia evolving to MonoMac syndrome, myelodysplasia, and acute myeloid leukemia

Two monogenic disorders masquerading as one: severe congenital neutropenia with monocytosis and non-syndromic sensorineural hearing loss

BACKGROUND

We report a large family with four successive generations, presenting with a complex phenotype of severe congenital neutropenia (SCN), partially penetrant monocytosis, and hearing loss of varying severity.

METHODS

We performed whole exome sequencing to identify the causative variants. Sanger sequencing was used to perform segregation analyses on remaining family members.

RESULTS

We identified and classified a pathogenic GFI1 variant and a likely pathogenic variant in MYO6 which together explain the complex phenotypes seen in this family.

CONCLUSIONS

We present a case illustrating the benefits of a broad screening approach that allows identification of oligogenic determinants of complex human phenotypes which may have been missed if the screening was limited to a targeted gene panel with the assumption of a syndromic disorder. This is important for correct genetic diagnosis of families and disentangling the range and severity of phenotypes associated with high impact variants.

Human genetics of life-threatening influenza pneumonitis

Influenza viruses infect millions of people around the globe annually, usually causing self-limited upper respiratory tract infections. However, a small but non-negligible proportion of patients suffer from life-threatening pulmonary disease. Those affected include otherwise healthy individuals, and children with primary infections in particular. Much effort has been devoted to virological studies of influenza and vaccine development. By contrast, the enormous interindividual variability in susceptibility to influenza has received very little attention. One interesting hypothesis is that interindividual variability is driven largely by the genetic makeup of the infected patients. Unbiased genomic approaches have been used to search for genetic lesions in children with life-threatening pulmonary influenza. Four monogenic causes of severe influenza pneumonitis—deficiencies of GATA2, IRF7, IRF9, and TLR3—have provided evidence that severe influenza pneumonitis can be genetic and often in patients with no other severe infections. These deficiencies highlight the importance of human type I and III IFN-mediated immunity for host defense against influenza. Clinical penetrance is incomplete, and the underlying mechanisms are not yet understood. However, human genetic studies have clearly revealed that seemingly sporadic and isolated life-threatening influenza pneumonitis in otherwise healthy individuals can be genetic.

Recent human genetic errors of innate immunity leading to increased susceptibility to infection

The germline encoded innate immunity governs eukaryotic host defense through both hematopoietic and non-hematopoietic cells, whereas adaptive immunity actions mainly via T cells and B cells characterized by their somatic genetic diversification of antigen-specific responses. Human inborn errors of innate immunity typically underlie infectious diseases. Disturbed innate immunity can additionally result in auto-inflammation. Here, we review inborn errors of innate immunity that have been recently discovered as well as new insights into previously described inborn errors of innate immunity.

Screening of genetic variants in ELANE mutation negative congenital neutropenia by next generation sequencing

AIMS

Congenital neutropenia (CN) is a rare inherited disease that results in recurrent, life-threatening bacterial infections due to a deficiency of mature neutrophils. They are usually caused by heterozygous ELANE mutations although mutations in other genes like HAX-1, G6PC3 and GFI1 have also been reported. Identifying the causative mutation aids in the establishment of diagnosis and rules out other secondary causes of neutropenia like autoimmune cytopenia and evolving aplasia. We aimed to identify the molecular defects in CN patients who had no mutations in ELANE gene, by next generation sequencing (NGS) targeting a customised panel of genes.

METHODS

DNA samples were sequenced with an Illumina NextSeq sequencer using an in-house customised panel of genes at ≥100× depth. Bioinformatics analysis was carried out and the pathogenic variants were identified using a stepwise filtering and analysis strategy. Specific mutations identified were subsequently validated by Sanger sequencing.

RESULTS

The pathogenic variants identified in the study includes previously reported variants in SBDS (compound heterozygous c.258+2T>C and c.1A>T), GATA2 (heterozygous c.1186C>T) and novel variants in WAS (hemizygous c.812T>C), JAGN1 (homozygous c.70G>A) and RTEL1 (heterozygous c.2893G>C) genes.

CONCLUSION

This study highlights that the absence of ELANE mutations does not rule out the diagnosis of CN and this NGS based approach with a customised panel will help in diagnostic confirmation in such patients. The early onset of the disease, clinical severity and associated high risk of malignant transformation in CN strongly suggests the need for early diagnosis and therapeutic intervention.

Quantitative and qualitative impairments in GATA2 and myeloid neoplasms

GATA2 is a key transcription factor critical for hematopoietic cell development. During the past decade, it became clear that heterozygous germline mutations in the GATA2 gene cause bone marrow failure and primary immunodeficiency syndrome, conditions that lead to a predisposition toward myeloid neoplasms, such as myelodysplastic syndrome, acute myeloid leukemia, and chronic myelomonocytic leukemia. Somatic mutations of the GATA2 gene are also involved in the pathogenesis of myeloid malignancies. Cases with GATA2 gene mutations are divided into two groups, resulting in either a quantitative deficiency or a qualitative defect in the GATA2 protein depending on the mutation position and type. In the former case, GATA2 mRNA expression from the mutant allele is markedly reduced or completely abrogated, and reduced GATA2 protein expression is involved in the pathogenesis. In the latter case, almost equal amounts of structurally abnormal and wildtype GATA2 proteins are predicted to be present and contribute to the pathogenesis. The development of mouse models of these human GATA2-related diseases has been undertaken, which naturally develop myeloid neoplasms.

Clinical Applications and Utility of a Precision Medicine Approach for Patients With Unexplained Cytopenias

OBJECTIVE

To demonstrate experience and feasibility of a precision medicine approach for patients with unexplained cytopenias, defined as low blood counts in one or more cell lineages, persistent for 6 months or longer, in the absence of known nutritional, autoimmune, infectious, toxic, and neoplastic (secondary) causes.

PATIENTS AND METHODS

Patients were evaluated in our clinic between November 8, 2016, and January 12, 2018. After a thorough evaluation of known causes, family history, and appropriate clinical assays, genomic evaluation was performed in a stepwise manner, through Sanger, targeted, and/or whole-exome sequencing. Variants were analyzed and discussed in a genomics tumor board attended by clinicians, bioinformaticians, and molecular biologists.

RESULTS

Sixty-eight patients were evaluated in our clinic. After genomic interrogation, they were classified into inherited bone marrow failure syndromes (IBMFS) (n=24, 35%), cytopenias without a known clinical syndrome which included idiopathic and clonal cytopenias of undetermined significance (CCUS) (n=30, 44%), and patients who did not fit into the above two categories ("others," n=14, 21%). A significant family history was found in only 17 (25%) patients (9 IBMFS, 2 CCUS, and 6 others), whereas gene variants were found in 43 (63%) patients (34 [79%] pathogenic including 12 IBMFS, 17 CCUS, and 5 others]. Genomic assessment resulted in a change in clinical management in 17 (25%) patients, as evidenced by changes in decisions with regards to therapeutic interventions (n=8, 47%), donor choice (n=6, 35%), and/or choice of conditioning regimen for hematopoietic stem cell transplantation (n=8, 47%).

CONCLUSION

We show clinical utility of a real-world algorithmic precision medicine approach for unexplained cytopenias.

Germline Predisposition to Hematolymphoid Neoplasia

OBJECTIVES

The 2017 Workshop of the Society for Hematopathology/European Association for Haematopathology aimed to review clinical cases with germline predisposition to hematolymphoid neoplasms.

METHODS

The Workshop Panel reviewed 51 cases with germline mutations and rendered consensus diagnoses. Of these, six cases were presented at the meeting by the submitting pathologists.

RESULTS

The cases submitted to the session covering germline predisposition included 16 cases with germline GATA2 mutations, 10 cases with germline RUNX1 mutations, two cases with germline CEBPA mutations, two germline TP53 mutations, and one case of germline DDX41 mutation. The most common diagnoses were acute myeloid leukemia (15 cases) and myelodysplastic syndrome (MDS, 14 cases).

CONCLUSIONS

The majority of the submitted neoplasms occurring in patients with germline predisposition were myeloid neoplasms with germline mutations in GATA2 and RUNX1. The presence of a germline predisposition mutation is not sufficient for a diagnosis of a neoplasm until the appearance of standard diagnostic features of a hematolymphoid malignancy manifest: in general, the diagnostic criteria for neoplasms associated with germline predisposition disorders are the same as those for sporadic cases.

Treatment of myelodysplastic syndrome in the era of next-generation sequencing

Next-generation sequencing (NGS) is rapidly changing the clinical care of patients with myelodysplastic syndrome (MDS). NGS can be used for various applications: (i) in the diagnostic process to discriminate between MDS and other diseases such as aplastic anaemia, myeloproliferative disorders and idiopathic cytopenias; (ii) for classification, for example, where the presence of SF3B1 mutation is one criterion for the ring sideroblast anaemia subgroups in the World Health Organization 2016 classification; (iii) for identification of patients suitable for targeted therapy (e.g. IDH1/2 inhibitors); (iv) for prognostication, for example, where specific mutations (e.g. TP53 and RUNX1) are associated with inferior prognosis, whereas others (e.g. SF3B1) are associated with superior prognosis; and (v) to monitor patients for progression or treatment failure. Most commonly, targeted sequencing for genes (normally 50-100 genes) reported to be recurrently mutated in myeloid disease is used. At present, NGS is rarely incorporated into clinical guidelines although an increasing number of studies have demonstrated the benefit of using NGS in the clinical management of MDS patients.

Severe influenza pneumonitis in children with inherited TLR3 deficiency

Autosomal recessive IRF7 and IRF9 deficiencies impair type I and III IFN immunity and underlie severe influenza pneumonitis. We report three unrelated children with influenza A virus (IAV) infection manifesting as acute respiratory distress syndrome (IAV-ARDS), heterozygous for rare TLR3 variants (P554S in two patients and P680L in the third) causing autosomal dominant (AD) TLR3 deficiency. AD TLR3 deficiency can underlie herpes simplex virus-1 (HSV-1) encephalitis (HSE) by impairing cortical neuron-intrinsic type I IFN immunity to HSV-1. TLR3-mutated leukocytes produce normal levels of IFNs in response to IAV. In contrast, TLR3-mutated fibroblasts produce lower levels of IFN-β and -λ, and display enhanced viral susceptibility, upon IAV infection. Moreover, the patients' iPSC-derived pulmonary epithelial cells (PECs) are susceptible to IAV. Treatment with IFN-α2b or IFN-λ1 rescues this phenotype. AD TLR3 deficiency may thus underlie IAV-ARDS by impairing TLR3-dependent, type I and/or III IFN-mediated, PEC-intrinsic immunity. Its clinical penetrance is incomplete for both IAV-ARDS and HSE, consistent with their typically sporadic nature.

Epidemiology of acute myeloid leukemia: Recent progress and enduring challenges

Acute myeloid leukemia (AML) is a malignant disorder of the bone marrow which is characterized by the clonal expansion and differentiation arrest of myeloid progenitor cells. The age-adjusted incidence of AML is 4.3 per 100,000 annually in the United States (US). Incidence increases with age with a median age at diagnosis of 68 years in the US. The etiology of AML is heterogeneous. In some patients, prior exposure to therapeutic, occupational or environmental DNA-damaging agents is implicated, but most cases of AML remain without a clear etiology. AML is the most common form of acute leukemia in adults and has the shortest survival (5-year survival = 24%). Curative therapies, including intensive chemotherapy and allogeneic stem cell transplantation, are generally applicable to a minority of patients who are younger and fit, while most older individuals exhibit poor prognosis and survival. Differences in patient outcomes are influenced by disease characteristics, access to care including active therapies and supportive care, and other factors. After many years without therapeutic advances, several new therapies have been approved and are expected to impact patient outcomes, especially for older patients and those with refractory disease.

Mutational spectrum and associations with clinical features in patients with acute myeloid leukaemia based on next‑generation sequencing

The aim of the present study was to examine the associations between 112 acute myeloid leukaemia (AML)-associated genes and the prognosis and clinical features of AML using bioinformatics analysis in 62 patients with AML. A total of 61 gene mutations were identified, and ≥1 mutations were detected in 96.77% of the patients. A total of 11 frequent mutations were identified, including nucleophosmin 1 (NPM1), Fms related tyrosine kinase 3 (FLT3), DNA methyltransferase 3α (DNMT3A) and Notch 2 (NOTCH2), with a mutation rate of ≥10%. The FLT3 mutation was significantly associated with the white blood cell count at the time of diagnosis, and DNMT3A was significantly associated with the French-American-British subtype and cytogenetics of patients with AML. The FLT3, NPM1 and DNMT3A mutations were significantly associated with a poor overall survival (OS) in patients with AML. In addition, the co-mutation of DNMT3A-CCAAT enhancer binding protein α (CEBPA) was observed to be significantly associated with a poor OS in patients with AML. Furthermore, the functional enrichment analysis revealed that the co-mutations of FLT3-NOTCH2, SETBP1-CREBBP and DNMT3A-CEBPA were significantly enriched in processes of ‘negative regulation of cell differentiation’ and ‘immune system development’, indicating that these mutations may serve crucial roles in the diagnosis and treatment of AML.

Can somatic GATA2 mutation mimic germ line GATA2 mutation?

Somatic GATA2 mutation is associated with immunodeficiency and pulmonary alveolar proteinosis in a patient with myeloproliferative neoplasm.

Transcription factor mutations as a cause of familial myeloid neoplasms

The initiation and evolution of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are driven by genomic events that disrupt multiple genes controlling hematopoiesis. Human genetic studies have discovered germline mutations in single genes that instigate familial MDS/AML. The best understood of these genes encode transcription factors, such as GATA-2, RUNX1, ETV6, and C/EBPα, which establish and maintain genetic networks governing the genesis and function of blood stem and progenitor cells. Many questions remain unanswered regarding how genes and circuits within these networks function in physiology and disease and whether network integrity is exquisitely sensitive to or efficiently buffered from perturbations. In familial MDS/AML, mutations change the coding sequence of a gene to generate a mutant protein with altered activity or introduce frameshifts or stop codons or disrupt regulatory elements to alter protein expression. Each mutation has the potential to exert quantitatively and qualitatively distinct influences on networks. Consistent with this mechanistic diversity, disease onset is unpredictable and phenotypic variability can be considerable. Efforts to elucidate mechanisms and forge prognostic and therapeutic strategies must therefore contend with a spectrum of patient-specific leukemogenic scenarios. Here we illustrate mechanistic advances in our understanding of familial MDS/AML syndromes caused by germline mutations of hematopoietic transcription factors.

Genetic predisposition to MDS: clinical features and clonal evolution

Myelodysplastic syndrome (MDS) typically presents in older adults with the acquisition of age-related somatic mutations, whereas MDS presenting in children and younger adults is more frequently associated with germline genetic predisposition. Germline predisposition is increasingly recognized in MDS presenting at older ages as well. Although each individual genetic disorder is rare, as a group, the genetic MDS disorders account for a significant subset of MDS in children and young adults. Because many patients lack overt syndromic features, genetic testing plays an important role in the diagnostic evaluation. This review provides an overview of syndromes associated with genetic predisposition to MDS, discusses implications for clinical evaluation and management, and explores scientific insights gleaned from the study of MDS predisposition syndromes. The effects of germline genetic context on the selective pressures driving somatic clonal evolution are explored. Elucidation of the molecular and genetic pathways driving clonal evolution may inform surveillance and risk stratification, and may lead to the development of novel therapeutic strategies.

Myeloid malignancies with somatic GATA2 mutations can be associated with an immunodeficiency phenotype

Germline mutations in GATA2 are associated with a complex immunodeficiency and cancer predisposition syndrome. Somatic GATA2^mut in myeloid malignancies may impart a similar phenotype. We reviewed adult patients with a diagnosis of GATA2^mut hematological malignancy who were referred to our HHMC for genetic testing, and identified to have somatic GATA2^mut. Nine patients with a median age of 63 years were included. Six patients (66.7%) were males. Atypical CML and acute myeloid leukemia were the most common initial presentation. The median overall VAF was 47.14%. Monocytopenia was pronounced when the GATA2^mut involved the C-terminal ZFD. GATA2 N-terminal ZFD mutations tend to be co-mutated with biCEBPA^mut. Unlike germline GATA2 mutations, monocytopenia associated with somatic GATA2 mutations often resolved at remission. We concluded that similar to germline GATA2 mutations, a subset of somatic GATA2 mutations can impart a germline phenotype.

Life-threatening influenza pneumonitis in a child with inherited IRF9 deficiency

Life-threatening pulmonary influenza can be caused by inborn errors of type I and III IFN immunity. We report a 5-yr-old child with severe pulmonary influenza at 2 yr. She is homozygous for a loss-of-function IRF9 allele. Her cells activate gamma-activated factor (GAF) STAT1 homodimers but not IFN-stimulated gene factor 3 (ISGF3) trimers (STAT1/STAT2/IRF9) in response to IFN-α2b. The transcriptome induced by IFN-α2b in the patient's cells is much narrower than that of control cells; however, induction of a subset of IFN-stimulated gene transcripts remains detectable. In vitro, the patient's cells do not control three respiratory viruses, influenza A virus (IAV), parainfluenza virus (PIV), and respiratory syncytial virus (RSV). These phenotypes are rescued by wild-type IRF9, whereas silencing IRF9 expression in control cells increases viral replication. However, the child has controlled various common viruses in vivo, including respiratory viruses other than IAV. Our findings show that human IRF9- and ISGF3-dependent type I and III IFN responsive pathways are essential for controlling IAV.

Successful Nonmyeloablative Allogeneic Stem Cell Transplant in a Child With Emberger Syndrome and GATA2 Mutation

Emberger syndrome with underlying guanine-adenine-thymine-adenine 2 (GATA2) mutation is a rare disorder and very few successful nonmyeloablative allogeneic hematopoietic stem cell transplants (HSCTs) have been reported. We report a case of Emberger syndrome with GATA2 mutation in a 9-year-old girl who presented with congenital sensorineural deafness, warts, lymphedema, and Myelodysplastic syndrome. Her sister had died of a similar illness. She underwent a nonmyeloablative matched related donor peripheral blood HSCT with rabbit antithymoglobulin (5 mg/kg), fludarabine (160 mg/m), cyclophophamide (29 mg/kg), and total body irradiation (2 Gray). Graft versus host disease prophylaxis consisted of tacrolimus and mycophenolate moefetil. She had neutrophil engraftment on day+15 and fully donor chimerism by day+30. She developed limited chronic skin graft versus host disease on tapering off immunosuppression. She is disease free on day+475. The review of literature showed a total of 28 patients with GATA2 mutation have undergone HSCT mostly nonmyeloablative and overall survival is 75%. Nonmyeloablatove HSCT is feasible and safe for the patients with GATA2 mutation.

Challenges in Diagnosing Myelodysplastic Syndromes in the Era of Genetic Testing: Proceedings of the 13th Workshop of the European Bone Marrow Working Group

The 13th workshop of the European Bone Marrow Working Group in Utrecht, The Netherlands, was devoted to studying myelodysplastic syndromes (MDS) and their boundaries. The panel received 44 cases submitted to the 3 invited categories, which included: reactive cytopenias with dysplasia, idiopathic cytopenia of undetermined significance, clonal haematopoiesis of indeterminate potential, idiopathic dysplasia of uncertain significance and overt MDS. For this summary, we have selected 17 cases that highlight difficulties in separating true MDS from other causes of cytopenia and the intricate relationship between clonal haematopoiesis and true MDS. In addition, cases of overt MDS with challenging features were also selected. All cases were stained for p53 expression. Using instructive submitted cases we discuss the following: (1) cytopenia with clonal haematopoiesis not fulfilling MDS criteria, (2) cytopenia and/or dysplasia with germline mutations and/or familial history suggesting an underlying gene defect, (3) MDS based on a recurrent chromosomal abnormality and (4) overt MDS with diagnostic difficulties due to concurrent treatment or disease. The lively discussion in the open forum of the workshop illustrated the need for better integrative understanding of the evolution of acquired genetic abnormalities in haematopoiesis, and the challenge of diagnosing true MDS in cytopenic patients with genetic abnormalities, either germline or acquired.

Bacille Calmette-Guerin Complications in Newly Described Primary Immunodeficiency Diseases: 2010-2017

Bacille Calmette–Guerin (BCG) vaccine is widely used as a prevention strategy against tuberculosis. BCG is a live vaccine, usually given early in life in most countries. While safe to most recipients, it poses a risk to immunocompromised patients. Several primary immunodeficiency diseases (PIDD) have been classically associated with complications related to BCG vaccine. However, a number of new inborn errors of immunity have been described lately in which little is known about adverse reactions following BCG vaccination. The aim of this review is to summarize the existing data on BCG-related complications in patients diagnosed with PIDD described since 2010. When BCG vaccination status or complications were not specifically addressed in those manuscripts, we directly contacted the corresponding authors for further clarification. We also analyzed data on other mycobacterial infections in these patients. Based on our analysis, around 8% of patients with gain-of-function mutations in STAT1 had mycobacterial infections, including localized complications in 3 and disseminated disease in 4 out of 19 BCG-vaccinated patients. Localized BCG reactions were also frequent in activated PI3Kδ syndrome type 1 (3/10) and type 2 (2/18) vaccinated children. Also, of note, no BCG-related complications have been described in either CTLA4 or LRBA protein-deficient patients; and not enough information on BCG-vaccinated NFKB1 or NFKB2-deficient patients was available to drive any conclusions about these diseases. Despite the high prevalence of environmental mycobacterial infections in GATA2-deficient patients, only one case of BCG reaction has been reported in a patient who developed disseminated disease. In conclusion, BCG complications could be expected in some particular, recently described PIDD and it remains a preventable risk factor for pediatric PIDD patients.

Allogeneic hematopoietic cell transplantation in patients with GATA2 deficiency-a case report and comprehensive review of the literature

Recently, an immunodeficiency syndrome caused by guanine-adenine-thymine-adenine 2 (GATA2) deficiency has been described. The syndrome is characterized by (i) typical onset in early adulthood, (ii) profound peripheral blood cytopenias of monocytes, B lymphocytes, and NK cells, (iii) distinct susceptibility to disseminated non-tuberculous mycobacterial (NTM) and other opportunistic infections (particularly human papillomavirus), and (iv) a high risk of developing hematologic malignancies (myelodysplastic syndromes (MDS); acute myeloid leukemias (AML)). Considerable clinical heterogeneity exists among patients with GATA2 deficiency, but once infectious symptoms occur or MDS/AML arises, survival declines significantly. Allogeneic hematopoietic cell transplantation (HCT) currently provides the only curative treatment option for both MDS/AML and dysfunctional immunity with life-threatening opportunistic infections. Strategies regarding timing of allogeneic HCT, antimicrobial prophylaxis and treatment, intensity of the preparative regimen, and optimal donor and graft source have not been clearly defined due to the rarity of the disease. Here, we provide a comprehensive analysis of the available literature and published case reports on the use of allogeneic HCT in patients with GATA2 deficiency. In addition, a case of a young woman with GATA2 deficiency, who developed an immune reconstitution inflammatory syndrome in her mycobacterial skin lesions post allogeneic HCT is presented and illustrates distinct problems encountered in this disease context.

Germline GATA2 Mutation and Bone Marrow Failure

GATA2 deficiency is an immunodeficiency and bone marrow failure disorder caused by pathogenic variants in GATA2. It is inherited in an autosomal-dominant pattern or can be due to de novo sporadic germline mutation. Patients commonly have B-cell, dendritic cell, natural killer cell, and monocytopenias, and are predisposed to myelodysplastic syndrome, acute myeloid leukemia, and chronic myelomonocytic leukemia. Patients may suffer from disseminated human papilloma virus and mycobacterial infections, pulmonary alveolar proteinosis, and lymphedema. The bone marrow eventually takes on a characteristic hypocellular myelodysplasia with loss of monocytes and hematogones, megakaryocytes with separated nuclear lobes, micromegakaryocytes, and megakaryocytes with hypolobated nuclei.

Natural history of GATA2 deficiency in a survey of 79 French and Belgian patients

Heterozygous germline GATA2 mutations strongly predispose to leukemia, immunodeficiency, and/or lymphoedema. We describe a series of 79 patients (53 families) diagnosed since 2011, made up of all patients in France and Belgium, with a follow up of 2249 patients/years. Median age at first clinical symptoms was 18.6 years (range, 0-61 years). Severe infectious diseases (mycobacteria, fungus, and human papilloma virus) and hematologic malignancies were the most common first manifestations. The probability of remaining symptom-free was 8% at 40 years old. Among the 53 probands, 24 had missense mutations including 4 recurrent alleles, 21 had nonsense or frameshift mutations, 4 had a whole-gene deletion, 2 had splice defects, and 2 patients had complex mutations. There were significantly more cases of leukemia in patients with missense mutations (n=14 of 34) than in patients with nonsense or frameshift mutations (n=2 of 28). We also identify new features of the disease: acute lymphoblastic leukemia, juvenile myelomonocytic leukemia, fatal progressive multifocal leukoencephalopathy related to the JC virus, and immune/inflammatory diseases. A revised International Prognostic Scoring System (IPSS) score allowed a distinction to be made between a stable disease and hematologic transformation. Chemotherapy is of limited efficacy, and has a high toxicity with severe infectious complications. As the mortality rate is high in our cohort (up to 35% at the age of 40), hematopoietic stem cell transplantation (HSCT) remains the best choice of treatment to avoid severe infectious and/or hematologic complications. The timing of HSCT remains difficult to determine, but the earlier it is performed, the better the outcome.

GATA2 Deficiency Due to de Novo Complete Monoallelic Deletion in an Adolescent With Myelodysplasia

GATA2 deficiency is an inherited bone marrow failure syndrome that can manifest with myelodysplasia (myelodysplastic syndrome) with chromosomal aberrations and high risk of evolution to leukemia (particularly, acute myeloid leukemia); immunodeficiency with opportunistic infections; and/or lymphedema. It can be transmitted in families in autosomal-dominant fashion, or present de novo as sporadic disease in adults or children. The authors report a case of an adolescent male with features of GATA2 deficiency resulting from a complete monoallelic deletion, review chromosomal anomalies associated with this disorder, and discuss the management implications.

Lethal Influenza in Two Related Adults with Inherited GATA2 Deficiency

The pathogenesis of life-threatening influenza A virus (IAV) disease remains elusive, as infection is benign in most individuals. We studied two relatives who died from influenza. We Sanger sequenced GATA2 and evaluated the mutation by gene transfer, measured serum cytokine levels, and analyzed circulating T- and B-cells. Both patients (father and son, P1 and P2) died in 2011 of H1N1pdm IAV infection at the ages of 54 and 31 years, respectively. They had not suffered from severe or moderately severe infections in the last 17 (P1) and 15 years (P2). A daughter of P1 had died at 20 years from infectious complications. Low B-cell, NK- cell, and monocyte numbers and myelodysplastic syndrome led to sequence GATA2. Patients were heterozygous for a novel, hypomorphic, R396L mutation leading to haplo-insufficiency. B- and T-cell rearrangement in peripheral blood from P1 during the influenza episode showed expansion of one major clone. No T-cell receptor excision circles were detected in P1 and P3 since they were 35 and 18 years, respectively. Both patients presented an exuberant, interferon (IFN)-γ-mediated hypercytokinemia during H1N1pdm infection. No data about patients with viremia was available. Two previously reported adult GATA2-deficient patients died from severe H1N1 IAV infection; GATA2 deficiency may predispose to life-threatening influenza in adulthood. However, a role of other genetic variants involved in immune responses cannot be ruled out. Patients with GATA2 deficiency can reach young adulthood without severe infections, including influenza, despite long-lasting complete B-cell and natural killer (NK) cell deficiency, as well as profoundly diminished T-cell thymic output.

How I treat myelodysplastic syndromes of childhood

Pediatric myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal disorders with an annual incidence of 1 to 4 cases per million, accounting for less than 5% of childhood hematologic malignancies. MDSs in children often occur in the context of inherited bone marrow failure syndromes, which represent a peculiarity of myelodysplasia diagnosed in pediatric patients. Moreover, germ line syndromes predisposing individuals to develop MDS or acute myeloid leukemia have recently been identified, such as those caused by mutations in GATA2, ETV6, SRP72, and SAMD9/SAMD9-L Refractory cytopenia of childhood (RCC) is the most frequent pediatric MDS variant, and it has specific histopathologic features. Allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many children with MDSs and is routinely offered to all patients with MDS with excess of blasts, to those with MDS secondary to previously administered chemoradiotherapy, and to those with RCC associated with monosomy 7, complex karyotype, severe neutropenia, or transfusion dependence. Immune-suppressive therapy may be a treatment option for RCC patients with hypocellular bone marrow and the absence of monosomy 7 or a complex karyotype, although the response rate is lower than that observed in severe aplastic anemia, and a relevant proportion of these patients will subsequently need HSCT for either nonresponse or relapse.

Old and new tools in the clinical diagnosis of inherited bone marrow failure syndromes

Patients with inherited bone marrow failure syndromes (IBMFSs) classically present with specific patterns of cytopenias along with congenital anomalies and/or other physical features that are often recognizable early in life. However, increasing application of genomic sequencing and clinical awareness of subtle disease presentations have led to the recognition of IBMFS in pediatric and adult populations more frequently than previously realized, such as those with early onset myelodysplastic syndrome (MDS). Given the well-defined differences in clinical management needs and outcomes for aplastic anemia, acute myeloid leukemia, and MDS in patients with an IBMFS vs those occurring sporadically, as well as nonhematologic comorbidities in patients with IBMFSs, it is critical for hematologists to understand how to approach screening for the currently known IBMFSs. This review presents a practical approach for the clinical hematologist that outlines when to suspect an IBMFS and how to use various diagnostic tools, from physical examination to screening laboratory tests and genomics, for the diagnosis of the most frequent IBMFSs: Fanconi anemia, telomere biology disorders, Diamond-Blackfan anemia, GATA2 deficiency syndrome, Shwachman-Diamond syndrome, and severe congenital neutropenia.

New monogenic disorders identify more pathways to neutropenia: from the clinic to next-generation sequencing

Neutrophils are the most common type of leukocyte in human circulating blood and constitute one of the chief mediators for innate immunity. Defined as a reduction from a normal distribution of values, neutropenia results from a number of congenital and acquired conditions. Neutropenia may be insignificant, temporary, or associated with a chronic condition with or without a vulnerability to life-threatening infections. As an inherited bone marrow failure syndrome, neutropenia may be associated with transformation to myeloid malignancy. Recognition of an inherited bone marrow failure syndrome may be delayed into adulthood. The list of monogenic neutropenia disorders is growing, heterogeneous, and bewildering. Furthermore, greater knowledge of immune-mediated and drug-related causes makes the diagnosis and management of neutropenia challenging. Recognition of syndromic presentations and especially the introduction of next-generation sequencing are improving the accuracy and expediency of diagnosis as well as their clinical management. Furthermore, identification of monogenic neutropenia disorders is shedding light on the molecular mechanisms of granulopoiesis and myeloid malignancies.

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.

Congenital neutropenia in the era of genomics: classification, diagnosis, and natural history

This review focuses on the classification, diagnosis and natural history of congenital neutropenia (CN). CN encompasses a number of genetic disorders with chronic neutropenia and, for some, affecting other organ systems, such as the pancreas, central nervous system, heart, bone and skin. To date, 24 distinct genes have been associated with CN. The number of genes involved makes gene screening difficult. This can be solved by next-generation sequencing (NGS) of targeted gene panels. One of the major complications of CN is spontaneous leukaemia, which is preceded by clonal somatic evolution, and can be screened by a targeted NGS panel focused on somatic events.

Acquired Senescent T-Cell Phenotype Correlates with Clinical Severity in GATA Binding Protein 2-Deficient Patients

GATA binding protein 2 (GATA2) deficiency is a rare disorder of hematopoiesis, lymphatics, and immunity caused by spontaneous or autosomal dominant mutations in the GATA2 gene. Clinical manifestations range from neutropenia, lymphedema, deafness, to severe viral and mycobacterial infections, bone marrow failure, and acute myeloid leukemia. Patients also present with monocytopenia, dendritic cell, B- and natural killer (NK)-cell deficiency. We studied the T-cell and NK-cell compartments of four GATA2-deficient patients to assess if changes in these lymphocyte populations could be correlated with clinical phenotype. Patients with more severe clinical complications demonstrated a senescent T-cell phenotype whereas patients with lower clinical score had undetectable changes relative to controls. In contrast, patients’ NK-cells demonstrated an immature/activated phenotype that did not correlate with clinical score, suggesting an intrinsic NK-cell defect. These studies will help us to determine the contribution of T- and NK-cell dysregulation to the clinical phenotype of GATA2 patients, and may help to establish the most accurate therapeutic options for these patients. Asymptomatic patients may be taken into consideration for hematopoietic stem cell transplantation when dysregulation of T-cell and NK-cell compartment is present.

Differential effects on gene transcription and hematopoietic differentiation correlate with GATA2 mutant disease phenotypes

Heterozygous GATA2 mutations underlie an array of complex hematopoietic and lymphatic diseases. Analysis of the literature reporting three recurrent GATA2 germline (g) mutations (gT354M, gR396Q and gR398W) revealed different phenotype tendencies. Although all three mutants differentially predispose to myeloid malignancies, there was no difference in leukemia-free survival for GATA2 patients. Despite intense interest, the molecular pathogenesis of GATA2 mutation is poorly understood. We functionally characterized a GATA2 mutant allelic series representing major disease phenotypes caused by germline and somatic (s) mutations in zinc finger 2 (ZF2). All GATA2 mutants, except for sL359V, displayed reduced DNA-binding affinity and transactivation compared with wild type (WT), which could be attributed to mutations of arginines critical for DNA binding or amino acids required for ZF2 domain structural integrity. Two GATA2 mutants (gT354M and gC373R) bound the key hematopoietic differentiation factor PU.1 more strongly than WT potentially perturbing differentiation via sequestration of PU.1. Unlike WT, all mutants failed to suppress colony formation and some mutants skewed cell fate to granulocytes, consistent with the monocytopenia phenotype seen in GATA2-related immunodeficiency disorders. These findings implicate perturbations of GATA2 function shaping the course of development of myeloid malignancy subtypes and strengthen complete or nearly complete haploinsufficiency for predisposition to lymphedema.

Heterogeneity of GATA2-related myeloid neoplasms

The GATA2 gene codes for a master hematopoietic transcription factor that is essential for the proliferation and maintenance of hematopoietic stem and progenitor cells. Heterozygous germline mutations in GATA2 have been initially associated with several clinical entities that are now collectively defined as GATA2 deficiency. Despite pleiotropic clinical manifestations, the high propensity for the development of myelodysplastic syndromes (MDS) constitutes the most common clinical denominator of this major MDS predisposition syndrome. The immunological phenotypes can be variable and mostly include deficiency of monocytes and/or B cells. Thus far, nearly 380 GATA2-deficient patients had been reported, with a roughly estimated prevalence of myeloid neoplasia of at least 75%. The most common abnormal karyotypes associated with GATA2-related MDS are monosomy 7, der(1;7) and trisomy 8. The overall clinical penetrance seems to be nearly complete for this transcriptopathy disorder. The high-risk MDS subtypes and karyotypes, and the underlying immunodeficiency guide decision-making toward timely stem cell transplantation.

Allogeneic Hematopoietic Cell Transplantation Using Treosulfan-Based Conditioning for Treatment of Marrow Failure Disorders

Hematopoietic cell transplantation (HCT) is effective in the treatment of inherited marrow failure disorders and other nonmalignant diseases. Conventional myeloablative conditioning regimens have been associated with high transplant-related mortality, particularly in patients with comorbid conditions. Here we report on 14 patients with marrow failure disorders (Shwachman-Diamond syndrome, n = 3; Diamond Blackfan anemia, n = 4; GATA2 deficiency, n = 2; paroxysmal nocturnal hemoglobinuria, n = 4; and an undefined marrow failure disorder, n = 1) who underwent HCT on a prospective, phase II, multicenter clinical trial. Patients were given HLA-matched related (n = 2) or unrelated (n = 12) grafts after conditioning with treosulfan (42 g/m²), fludarabine (150 mg/m²), ± thymoglobulin (n = 11; 6 mg/kg). All patients engrafted. At a median follow-up of 3 years, 13 patients are alive with complete correction of their underlying disease. These results indicate that the combination of treosulfan, fludarabine, and thymoglobulin is effective at establishing donor engraftment with a low toxicity profile and excellent disease-free survival in patients with marrow failure disorders.

GATA2 deficiency and related myeloid neoplasms

The GATA2 gene codes for a hematopoietic transcription factor that through its two zinc fingers (ZF) can occupy GATA-DNA motifs in a countless number of genes. It is crucial for the proliferation and maintenance of hematopoietic stem cells. During the past 5 years, germline heterozygous mutations in GATA2 were reported in several hundred patients with various phenotypes ranging from mild cytopenia to severe immunodeficiency involving B cells, natural killer cells, CD4+ cells, monocytes and dendritic cells (MonoMAC/DCML), and myeloid neoplasia. Some patients additionally show syndromic features such as congenital deafness and lymphedema (originally defining the Emberger syndrome) or pulmonary disease and vascular problems. The common clinical denominator in all reported cohorts is the propensity for myeloid neoplasia (myelodysplastic syndrome [MDS], myeloproliferative neoplasms [MPN], chronic myelomonocytic leukemia [CMML], acute myeloid leukemia [AML]) with an overall prevalence of approximately 75% and a median age of onset of roughly 20 years. Three major mutational types are encountered in GATA2-deficient patients: truncating mutations prior to ZF2, missense mutations within ZF2, and noncoding variants in the +9.5kb regulatory region of GATA2. Recurrent somatic lesions comprise monosomy 7 and trisomy 8 karyotypes and mutations in SETBP1 and ASXL1 genes. The high risk for progression to advanced myeloid neoplasia and life-threatening infectious complications guide decision-making towards timely stem cell transplantation.

Successful Myeloablative Matched Unrelated Donor Hematopoietic Stem Cell Transplantation in a Young Girl With GATA2 Deficiency and Emberger Syndrome

Patients with GATA2 (Emberger syndrome) deficiency needs early hematopoietic stem cell transplant (HSCT) before evolving in to myelodysplastic syndrome or acute myeloid leukemia and with time given compromised organ dysfunction leads to increase regimen-related toxicities. Most published cases have used nonmyeloablative conditioning regimens, show higher incidences of rejection and relapse rates and umbilical cord blood transplant has been reported to be suboptimal in patients with GATA2 deficiency because of longer period of engraftment leads to more infections and mortality. We report a 4.5-year-old girl with GATA2 deficiency who underwent matched unrelated donor HSCT utilizing a myeloablative conditioning regimen including intravenous busulfan (total dose of 12.8 mg/kg) and fludarabine (total dose of 160 mg/m) She tolerated the conditioning regimen and bone marrow infusion well. Her initial chimerism was mixed (90% donor), cyclosporine was gradually weaned and discontinued at day+85 and this resulted in conversion to full-donor chimerism. Bone marrow assessment 3 months post-HSCT revealed normal hematopoiesis and absence of monosomy 7. At 20 months of follow-up she had full-donor chimerism with complete reconstitution of the all hematopoietic stem cells. Myeloablative matched unrelated donor HSCT represents an effective option for cure in patients with GATA2 deficiency and Emberger syndrome.

Adaptive NK cells can persist in patients with GATA2 mutation depleted of stem and progenitor cells

Heterozygous GATA2 mutation is associated with immunodeficiency, lymphedema, and myelodysplastic syndrome. Disease presentation is variable, often coinciding with loss of circulating dendritic cells, monocytes, B cells, and natural killer (NK) cells. Nonetheless, in a proportion of patients carrying GATA2 mutation, NK cells persist. We found that peripheral blood NK cells in symptomatic patients uniformly lacked expression of the transcription factor promyelocytic leukemia zinc finger (PLZF), as well as expression of intracellular signaling proteins FcεRγ, spleen tyrosine kinase (SYK), and EWS/FLI1-Activated Transcript 2 (EAT-2) in a variegated manner. Moreover, consistent with an adaptive identity, NK cells from patients with GATA2 mutation displayed altered expression of cytotoxic granule constituents and produced interferon-γ upon Fc-receptor engagement but not following combined interleukin-12 (IL-12) and IL-18 stimulation. Canonical, PLZF-expressing NK cells were retained in asymptomatic carriers of GATA2 mutation. Developmentally, GATA-binding protein-2 (GATA-2) was expressed in hematopoietic stem cells, but not in NK-cell progenitors, CD3^-CD56^bright, canonical, or adaptive CD3^-CD56^dim NK cells. Peripheral blood NK cells from individuals with GATA2 mutation proliferated normally in vitro, whereas lineage-negative progenitors displayed impaired NK-cell differentiation. In summary, adaptive NK cells can persist in patients with GATA2 mutation, even after NK-cell progenitors expire. Moreover, our data suggest that adaptive NK cells are more long-lived than canonical, immunoregulatory NK cells.

The GATA factor revolution in hematology

The discovery of the GATA binding protein (GATA factor) transcription factor family revolutionized hematology. Studies of GATA proteins have yielded vital contributions to our understanding of how hematopoietic stem and progenitor cells develop from precursors, how progenitors generate red blood cells, how hemoglobin synthesis is regulated, and the molecular underpinnings of nonmalignant and malignant hematologic disorders. This thrilling journey began with mechanistic studies on a β-globin enhancer- and promoter-binding factor, GATA-1, the founding member of the GATA family. This work ushered in the cloning of related proteins, GATA-2-6, with distinct and/or overlapping expression patterns. Herein, we discuss how the hematopoietic GATA factors (GATA-1-3) function via a battery of mechanistic permutations, which can be GATA factor subtype, cell type, and locus specific. Understanding this intriguing protein family requires consideration of how the mechanistic permutations are amalgamated into circuits to orchestrate processes of interest to the hematologist and more broadly.

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.