Haematopoietic and immune defects associated with GATA2 mutation

Chronic neutropenia: how best to assess severity and approach management?

INTRODUCTION

Neutropenia is a relatively common finding in medical practice and the medical approach requires a gradual and pertinent diagnostic procedure as well as adapted management.

AREAS COVERED

The area of chronic neutropenia remains fragmented between diverse diseases or situations. Here physicians involved in different aspects of chronic neutropenia gather both the data from medical literature till the end of May 2021 and their experience to offer a global approach for the diagnosis of chronic neutropenia as well as their medical care.

EXPERT OPINION

In most cases, the neutropenia is transient, frequently related to a viral infection, and not harmful. However, neutropenia can be chronic (i.e. >3 months) and related to a number of etiologies, some clinically benign, such as so-called 'ethnic' neutropenia. Autoimmune neutropenia is the common form in young children, whereas idiopathic/immune neutropenia is a frequent etiology in young females. Inherited neutropenia (or congenital neutropenia) is exceptional, with approximately 30 new cases per 10⁶ births and 30 known subtypes. Such patients have a high risk of invasive bacterial infections, and oral infections. Supportive therapy, which is primarily based on daily administration of an antibiotic prophylaxis and/or treatment with granulocyte-colony stimulating factor (G-CSF), contributes to avoiding recurrent infections.

Gata2 heterozygous mutant mice exhibit reduced inflammatory responses and impaired bacterial clearance

Infectious diseases continually pose global medical challenges. The transcription factor GATA2 establishes gene networks and defines cellular identity in hematopoietic stem/progenitor cells and in progeny committed to specific lineages. GATA2-haploinsufficient patients exhibit a spectrum of immunodeficiencies associated with bacterial, viral, and fungal infections. Despite accumulating clinical knowledge of the consequences of GATA2 haploinsufficiency in humans, it is unclear how GATA2 haploinsufficiency compromises host anti-infectious defenses. To address this issue, we examined Gata2-heterozygous mutant (G2 Het) mice as a model for human GATA2 haploinsufficiency. In vivo inflammation imaging and cytokine multiplex analysis demonstrated that G2 Het mice had attenuated inflammatory responses with reduced levels of inflammatory cytokines, particularly IFN-γ, IL-12p40, and IL-17A, during lipopolysaccharide-induced acute inflammation. Consequently, bacterial clearance was significantly impaired in G2 Het mice after cecal ligation and puncture-induced polymicrobial peritonitis. These results provide direct molecular insights into GATA2-directed host defenses and the pathogenic mechanisms underlying observed immunodeficiencies in GATA2-haploinsufficient patients.

GATA2 and marrow failure

GATA2 gene encodes a zinc finger transcription factor crucial for normal hematopoiesis. Its haploinsufficiency, caused by a great variety of heterozygous loss-of-function mutations, underlies one of the most common causes of inherited bone marrow failure, recognized as GATA2 deficiency. Its phenotype is characterized by a broad spectrum of clinical presentations, including: haematological malignancies; immunodeficiency leading to invasive viral, mycobacterial and fungal infections; recurrent warts; lymphedema; pulmonary alveolar proteinosis; deafness; and miscarriage. The onset of symptoms ranges from early childhood to late adulthood, more frequently between adolescence and early adulthood. The only curative treatment is allogenic hematopoietic stem cell transplantation (HSCT), that can restore the function of both hematopoietic and immune system and prevent lung deterioration. Currently, there are no consensus guidelines about the management of patients affected by GATA2 deficiency, especially with regard to the optimal time to proceed to HSCT.

GATA2 deficiency syndrome: A decade of discovery

GATA2 deficiency syndrome (G2DS) is a rare autosomal dominant genetic disease predisposing to a range of symptoms, of which myeloid malignancy and immunodeficiency including recurrent infections are most common. In the last decade since it was first reported, there have been over 480 individuals identified carrying a pathogenic or likely pathogenic germline GATA2 variant with symptoms of G2DS, with 240 of these confirmed to be familial and 24 de novo. For those that develop myeloid malignancy (75% of all carriers with G2DS disease symptoms), the median age of onset is 17 years (range 0-78 years) and myelodysplastic syndrome is the first diagnosis in 75% of these cases with acute myeloid leukemia in a further 9%. All variant types appear to predispose to myeloid malignancy and immunodeficiency. Apart from lymphedema in which haploinsufficiency seems necessary, the mutational requirements of the other less common G2DS phenotypes is still unclear. These predominantly loss-of-function variants impact GATA2 expression and function in numerous ways including perturbations to DNA binding, protein structure, protein:protein interactions, and gene transcription, splicing, and expression. In this review, we provide the first expert-curated ACMG/AMP classification with codes of published variants compatible for use in clinical or diagnostic settings.

GATA2 rs2335052 and GATA2 rs78245253 single-nucleotide polymorphisms in Chinese patients with acute myelocytic leukemia

INTRODUCTION

GATA binding protein 2 (GATA2) gene, involved in progression of hematologic malignancies and various solid tumors, is a susceptibility gene for inherited acute myeloid leukemia (AML). However, the influence of its single-nucleotide polymorphisms (SNPs) on AML remains unknown.

METHODS

We used allele-specific PCR to genotype GATA2 rs2335052 and rs78245253 in 159 newly diagnosed AML (non-M3) patients and 300 healthy volunteers, and all of participants came from China. And 34 common hematological tumor gene mutations in 159 AML patients were detected by next-generation sequencing. Kaplan-Meier survival analysis and Cox proportional hazard regression were used to analyze the association between the two SNPs and the prognosis of AML.

RESULTS

We found GATA2 rs2335052 C/T genotype, rs2335052 T/T genotype and rs78245253 G/C genotype in 51.6%, 13.8% and 11.3% AML patients. Our results demonstrated that GATA2 rs2335052 and rs78245253 were associated with certain laboratory features in AML patients, which had no effect on the pathogeny, chemotherapy response and recurrence of patients. Nevertheless, Kaplan-Meier survival analysis showed that, compared with rs78245253 G/G genotype, rs78245253 G/C genotype was significantly related to a decrease in overall survival (OS) (P = .020). Additionally, multivariate cox regression analysis showed that GATA2 rs78245253 was an independent risk factor for OS of AML patients in China.

CONCLUSION

GATA2 rs78245253 was an independent predictor for prognosis of AML patients in China and may be used as a potential indicator to predict the survival of AML patients in China. Further studies are needed to validate these findings and clarify the underlying mechanism.

Mycobacterial diseases in patients with inborn errors of immunity

Clinical disease caused by the agent of tuberculosis, Mycobacterium tuberculosis, and by less virulent mycobacteria, such as bacillus Calmette-Guérin (BCG) vaccines and environmental mycobacteria, can result from inborn errors of immunity (IEIs). IEIs underlie more than 450 conditions, each associated with an impairment of the development and/or function of hematopoietic and/or non-hematopoietic cells involved in host defense. Only a minority of IEIs confer predisposition to mycobacterial disease. The IEIs underlying susceptibility to bona fide tuberculosis are less well delineated than those responsible for susceptibility to less virulent mycobacteria. However, all these IEIs share a defining feature: the impairment of immunity mediated by interferon gamma (IFN-γ). More profound IFN-γ deficiency is associated with a greater vulnerability to weakly virulent mycobacteria, whereas more selective IFN-γ deficiency is associated with a more selective predisposition to mycobacterial disease. We review here recent progress in the study of IEIs underlying mycobacterial diseases.

Single-cell ATAC-seq reveals GATA2-dependent priming defect in myeloid and a maturation bottleneck in lymphoid lineages

Germline heterozygous mutations in GATA2 are associated with a syndrome characterized by cytopenias, atypical infections, and increased risk of hematologic malignancies. Here, we generated a zebrafish mutant of gata2b that recapitulated the myelomonocytopenia and B-cell lymphopenia of GATA2 deficiency syndrome. Using single-cell assay for transposase accessible chromatin with sequencing of marrow cells, we showed that loss of gata2b led to contrasting alterations in chromosome accessibility in early myeloid and lymphoid progenitors, associated with defects in gene expression. Within the myeloid lineage in gata2b mutant zebrafish, we identified an attenuated myeloid differentiation with reduced transcriptional priming and skewing away from the monocytic program. In contrast, in early lymphoid progenitors, gata2b loss led to accumulation of B-lymphoid transcription factor accessibility coupled with increased expression of the B-cell lineage-specification program. However, gata2b mutant zebrafish had incomplete B-cell lymphopoiesis with loss of lineage-specific transcription factor accessibility in differentiating B cells, in the context of aberrantly reduced oxidative metabolic pathways. Our results establish that transcriptional events in early progenitors driven by Gata2 are required to complete normal differentiation.

Autoimmune pulmonary alveolar proteinosis successfully treated with lung lavage in an adolescent patient: a case report

Background

Pulmonary alveolar proteinosis is a rare interstitial lung disease characterized by accumulating surfactant materials in the alveoli. The autoimmune form is by far the most common in adults, while in the pediatric age group, the vast majority of cases are congenital. We report a case of an adolescent patient diagnosed with autoimmune pulmonary alveolar proteinosis, which is unusual in this age group.

Case presentation

A-15 year-old Saudi male presented to the emergency department with a history of shortness of breath and low oxygen saturation. High-resolution computed tomography of his chest showed a global crazy-paving pattern. Autoantibodies against granulocyte-macrophage colony-stimulating factor were detected in his serum. A diagnosis of the autoimmune form of pulmonary alveolar proteinosis was confirmed after excluding other possible causes. The patient improved after he underwent whole lung lavage under general anesthesia, and he was independent of oxygen therapy after 6 months of follow-up.

Conclusion

The autoimmune form of pulmonary alveolar proteinosis is rare in the pediatric age group and should be considered when no apparent cause of this disease was found. Whole lung lavage should be the first treatment modality offered in this setting with close follow-up and monitoring.

Approach to the diagnosis of aplastic anemia

Establishing a diagnosis of aplastic anemia (AA) can be challenging, but it is absolutely critical to appropriate management, especially differentiating between acquired and inherited forms of the disease. The hematology field requires updated diagnostic guidelines to ensure that appropriate clinical pathways are pursued for patients and their safety. There are increasing clinical options for patients with immunosuppressive therapy and transplant once the diagnosis is made. In a case-based format, this review emphasizes the newer data on molecular (somatic and germline) findings in AA and how they are (or are not) helpful during diagnosis. There are key details on somatic mutation profiles and stated evidence where available for prognostic and treatment indications. Germline details of newer syndromes are also outlined, which make this review modern and reflect areas of uncertainty for clinicians.

Pediatric Myelodysplastic Syndromes

Pediatric myelodysplastic syndromes (MDS) comprise less than 5% of childhood malignancies. Approximately 30% to 45% of pediatric MDS cases are associated with an underlying genetic predisposition syndrome. A subset of patients present with MDS/acute myeloid leukemia (AML) following intensive chemotherapy for an unrelated malignancy. A definitive diagnosis of MDS can often only be rendered pending a comprehensive clinical and laboratory-based evaluation, which frequently includes ancillary testing in a reference laboratory. Clinical subtypes, the current diagnostic schema, and the results of more recently performed next-generation sequencing studies in pediatric MDS are discussed here.

Gata2-L359V impairs primitive and definitive hematopoiesis and blocks cell differentiation in murine chronic myelogenous leukemia model

GATA2, a key transcription factor in hematopoiesis, is frequently mutated in hematopoietic malignancies. How the GATA2 mutants contribute to hematopoiesis and malignant transformation remains largely unexplored. Here, we report that Gata2-L359V mutation impeded hematopoietic differentiation in murine embryonic and adult hematopoiesis and blocked murine chronic myeloid leukemia (CML) cell differentiation. We established a Gata2-L359V knockin mouse model in which the homozygous Gata2-L359V mutation caused major defects in primitive erythropoiesis with an accumulation of erythroid precursors and severe anemia, leading to embryonic lethality around E11.5. During adult life, the Gata2-L359V heterozygous mice exhibited a notable decrease in bone marrow (BM) recovery under stress induction with cytotoxic drug 5-fluorouracil. Using RNA sequencing, it was revealed that homozygous Gata2-L359V suppressed genes related to embryonic hematopoiesis in yolk sac, while heterozygous Gata2-L359V dysregulated genes related to cell cycle and proliferation in BM Lin^-Sca1⁺c-kit⁺ cells. Furthermore, through chromatin immunoprecipitation sequencing and transactivation experiments, we found that this mutation enhanced the DNA-binding capacity and transcriptional activities of Gata2, which was likely associated with the altered expression of some essential genes during embryonic and adult hematopoiesis. In mice model harboring BCR/ABL, single-cell RNA-sequencing demonstrated that Gata2-L359V induced additional gene expression profile abnormalities and partially affected cell differentiation at the early stage of myelomonocytic lineage, evidenced by the increase of granulocyte-monocyte progenitors and monocytosis. Taken together, our study unveiled that Gata2-L359V mutation induces defective hematopoietic development and blocks the differentiation of CML cells.

Human GATA2 mutations and hematologic disease: how many paths to pathogenesis?

The surge of human genetic information, enabled by increasingly facile and economically feasible genomic technologies, has accelerated discoveries on the relationship of germline genetic variation to hematologic diseases. For example, germline variation in GATA2, encoding a vital transcriptional regulator of multilineage hematopoiesis, creates a predisposition to bone marrow failure and acute myeloid leukemia termed GATA2 deficiency syndrome. More than 300 GATA2 variants representing missense, truncating, and noncoding enhancer mutations have been documented. Although these variants can diminish GATA2 expression and/or function, the functional ramifications of many variants are unknown. Studies using genetic rescue and knockin mouse systems have established that GATA2 mutations differentially affect molecular processes in distinct target genes and within a single target cell. Considering that target genes for a transcription factor can differ in sensitivity to altered levels of the factor, and transcriptional mechanisms are often cell type specific, the context-dependent consequences of GATA2 mutations in experimental systems portend the complex phenotypes and interindividual variation of GATA2 deficiency syndrome. This review documents GATA2 human genetics and the state of efforts to traverse from physiological insights to pathogenic mechanisms.

Sequencing of RNA in single cells reveals a distinct transcriptome signature of hematopoiesis in GATA2 deficiency

Constitutional GATA2 deficiency caused by heterozygous germline GATA2 mutations has a broad spectrum of clinical phenotypes, including systemic infections, lymphedema, cytopenias, and myeloid neoplasms. Genotype-phenotype correlation is not well understood mechanistically in GATA2 deficiency. We performed whole transcriptome sequencing of single hematopoietic stem and progenitor cells from 8 patients, who had pathogenic GATA2 mutations and myelodysplasia. Mapping patients' cells onto normal hematopoiesis, we observed deficiency in lymphoid/myeloid progenitors, also evident from highly constrained gene correlations. HSPCs of patients exhibited distinct patterns of gene expression and coexpression compared with counterparts from healthy donors. Distinct lineages showed differently altered transcriptional profiles. Stem cells in patients had dysregulated gene expression related to apoptosis, cell cycle, and quiescence; increased expression of erythroid/megakaryocytic priming genes; and decreased lymphoid priming genes. The prominent deficiency in lympho-myeloid lineages in GATA2 deficiency appeared at least partly due to the expression of aberrant gene programs in stem cells prior to lineage commitment. We computationally imputed cells with chromosomal abnormalities and determined their gene expression; DNA repair genes were downregulated in trisomy 8 cells, potentially rendering these cells vulnerable to second-hit somatic mutations and additional chromosomal abnormalities. Cells with complex cytogenetic abnormalities showed defects in genes related to multilineage differentiation and cell cycle. Single-cell RNA sequencing is powerful in resolving transcriptomes of cell subpopulations despite a paucity of cells in marrow failure. Our study discloses previously uncharacterized transcriptome signatures of stem cells and progenitors in GATA2 deficiency, providing a broad perspective of potential mechanisms by which germline mutations modulate early hematopoiesis in a human disease. This trial was registered at www.clinicaltrials.gov as NCT01905826, NCT01861106, and NCT00001620.

Somatic GATA2 mutations define a subgroup of myeloid malignancy patients at high risk for invasive fungal disease

Invasive fungal disease (IFD) can be a severe treatment complication in patients with myeloid malignancies, but current risk models do not incorporate disease-specific factors, such as somatic gene mutations. Germline GATA2 deficiency is associated with a susceptibility to IFD. To determine whether myeloid gene mutations were associated with IFD risk, we identified 2 complementary cohorts of patients with myeloid malignancy, based on (1) the diagnosis of invasive aspergillosis (IA), or (2) the presence of GATA2 mutations identified during standard clinical sequencing. We found somatic GATA2 mutations in 5 of 27 consecutive patients who had myeloid malignancy and developed IA. Among 51 consecutive patients with GATA2 mutations identified in the evaluation of myeloid malignancy, we found that IFD was diagnosed and treated in 21 (41%), all of whom had received chemotherapy or had undergone an allogeneic stem cell transplant. Pulmonary infections and disseminated candidiasis were most common. The 90-day mortality was 52% among patients with IFD. Our results indicate that patients with somatic GATA2 mutations are a vulnerable subgroup of patients with myeloid malignancy who have high risk for treatment-associated IFD and suggest that a focused approach to antifungal prophylaxis be considered.

Difference in gene mutation profile in patients with refractory/relapsed versus newly diagnosed acute myeloid leukemia based on targeted next-generation sequencing

We have reported the genetic mutation profile in previously untreated acute myeloid leukemia (AML) patients using a targeted NGS screening method. In this study, we evaluated the characteristics and prognostic significance of gene mutations in refractory/relapsed (R/R) AML patients by comparing their gene mutation spectrum to those newly diagnosed. The frequencies of tumor suppressor mutations were increased, while the mutation frequencies of nucleophosmin and spliceosome complex were decreased in relapsed AML. The frequency of FLT3-ITD mutation was increased, while that of CEBPA biallelic mutation decreased in refractory AML. Activated signaling mutations predicted a lower complete remission rate. FLT3-ITD mutation predicted an inferior overall survival after relapse. DNMT3A mutation predicted an inferior relapse-free survival in R/R AML. These findings may shed light on the molecular mechanism study of leukemia refractory or relapse and provide new guidance for the dynamic risk assessment of AML.

Inherited deficiency of stress granule ZNFX1 in patients with monocytosis and mycobacterial disease

Human inborn errors of IFN-γ underlie mycobacterial disease, due to insufficient IFN-γ production by lymphoid cells, impaired myeloid cell responses to this cytokine, or both. We report four patients from two unrelated kindreds with intermittent monocytosis and mycobacterial disease, including bacillus Calmette-Guérin-osis and disseminated tuberculosis, and without any known inborn error of IFN-γ. The patients are homozygous for ZNFX1 variants (p.S959* and p.E1606Rfs*10) predicted to be loss of function (pLOF). There are no subjects homozygous for pLOF variants in public databases. ZNFX1 is a conserved and broadly expressed helicase, but its biology remains largely unknown. It is thought to act as a viral double-stranded RNA sensor in mice, but these patients do not suffer from severe viral illnesses. We analyze its subcellular localization upon overexpression in A549 and HeLa cell lines and upon stimulation of THP1 and fibroblastic cell lines. We find that this cytoplasmic protein can be recruited to or even induce stress granules. The endogenous ZNFX1 protein in cell lines of the patient homozygous for the p.E1606Rfs*10 variant is truncated, whereas ZNFX1 expression is abolished in cell lines from the patients with the p.S959* variant. Lymphocyte subsets are present at normal frequencies in these patients and produce IFN-γ normally. The hematopoietic and nonhematopoietic cells of the patients tested respond normally to IFN-γ. Our results indicate that human ZNFX1 is associated with stress granules and essential for both monocyte homeostasis and protective immunity to mycobacteria.

Inherited GATA2 Deficiency Is Dominant by Haploinsufficiency and Displays Incomplete Clinical Penetrance

PURPOSE

Germline heterozygous mutations of GATA2 underlie a variety of hematological and clinical phenotypes. The genetic, immunological, and clinical features of GATA2-deficient patients with mycobacterial diseases in the familial context remain largely unknown.

METHODS

We enrolled 15 GATA2 index cases referred for mycobacterial disease. We describe their genetic and clinical features including their relatives.

RESULTS

We identified 12 heterozygous GATA2 mutations, two of which had not been reported. Eight of these mutations were loss-of-function, and four were hypomorphic. None was dominant-negative in vitro, and the GATA2 locus was found to be subject to purifying selection, strongly suggesting a mechanism of haploinsufficiency. Three relatives of index cases had mycobacterial disease and were also heterozygous, resulting in 18 patients in total. Mycobacterial infection was the first clinical manifestation in 11 patients, at a mean age of 22.5 years (range: 12 to 42 years). Most patients also suffered from other infections, monocytopenia, or myelodysplasia. Strikingly, the clinical penetrance was incomplete (32.9% by age 40 years), as 16 heterozygous relatives aged between 6 and 78 years, including 4 older than 60 years, were completely asymptomatic.

CONCLUSION

Clinical penetrance for mycobacterial disease was found to be similar to other GATA2 deficiency-related manifestations. These observations suggest that other mechanisms contribute to the phenotypic expression of GATA2 deficiency. A diagnosis of autosomal dominant GATA2 deficiency should be considered in patients with mycobacterial infections and/or other GATA2 deficiency-related phenotypes at any age in life. Moreover, all direct relatives should be genotyped at the GATA2 locus.

Severe influenza in a paediatric patient with GATA2 deficiency and Emberger syndrome

A 9-year-old girl was admitted to the paediatric intensive care unit with acute respiratory failure due to influenza. Nine months earlier, she presented with unexplained lymphoedema of the lower extremities and monocytopenia. She had a history of occasional finger warts and onychomycoses. During hospitalisation, the patient was diagnosed with Emberger syndrome caused by GATA2 deficiency. The admission was complicated by thromboses in the right hand, leading to amputation of multiple fingers. From then on, the patient has been in good recovery, the function of her right hand was improving and an allogeneic haematopoietic cell transplantation has now been successfully performed.

Many signs, one mutation: Early onset of de novo GATA2 deficiency syndrome. A case report

We report a case with a broad spectrum of symptoms, related to GATA2 deficiency syndrome, which emerged as early as at 6 months of age. They ranged from lymphedema, deafness to myelodysplastic syndrome (MDS).

A Next-Generation Sequencing Test for Severe Congenital Neutropenia: Utility in a Broader Clinicopathologic Spectrum of Disease

Severe congenital neutropenia (SCN) is a collection of diverse disorders characterized by chronically low absolute neutrophil count in the peripheral blood, increased susceptibility to infection, and a significant predisposition to the development of myeloid malignancies. SCN can be acquired or inherited. Inherited forms have been linked to variants in a group of diverse genes involved in the neutrophil-differentiation process. Variants that promote resistance to treatment have also been identified. Thus, genetic testing is important for the diagnosis, prognosis, and management of SCN. Herein we describe clinically validated assay developed for assessing patients with suspected SCN. The assay is performed from a whole-exome backbone. Variants are called across all coding exons, and results are filtered to focus on 48 genes that are clinically relevant to SCN. Validation results indicated 100% analytical sensitivity and specificity for the detection of constitutional variants among the 48 reportable genes. To date, 34 individuals have been referred for testing (age range: birth to 67 years). Several pathogenic and likely pathogenic variants have been identified, including one in a patient with late-onset disease. The pattern of cases referred for testing suggests that this assay has clinical utility in a broader spectrum of patients beyond those in the pediatric population who have classic early-onset symptoms characteristic of SCN.

Efferocytic Defects in Early Atherosclerosis Are Driven by GATA2 Overexpression in Macrophages

The loss of efferocytosis-the phagocytic clearance of apoptotic cells-is an initiating event in atherosclerotic plaque formation. While the loss of macrophage efferocytosis is a prerequisite for advanced plaque formation, the transcriptional and cellular events in the pre-lesion site that drive these defects are poorly defined. Transcriptomic analysis of macrophages recovered from early-stage human atherosclerotic lesions identified a 50-fold increase in the expression of GATA2, a transcription factor whose expression is normally restricted to the hematopoietic compartment. GATA2 overexpression in vitro recapitulated many of the functional defects reported in patient macrophages, including deficits at multiple stages in the efferocytic process. These findings included defects in the uptake of apoptotic cells, efferosome maturation, and in phagolysosome function. These efferocytic defects were a product of GATA2-driven alterations in the expression of key regulatory proteins, including Src-family kinases, Rab7 and components of both the vacuolar ATPase and NADPH oxidase complexes. In summary, these data identify a mechanism by which efferocytic capacity is lost in the early stages of plaque formation, thus setting the stage for the accumulation of uncleared apoptotic cells that comprise the bulk of atherosclerotic plaques.

GATA2 Related Conditions and Predisposition to Pediatric Myelodysplastic Syndromes

Simple Summary

GATA2 deficiency is considered one of the most common cancer predisposition syndromes determining myelodysplastic syndrome in children. Little is known of this recently described syndrome, often resulting in a misdiagnosis and unclear management. In this review, we describe GATA2 deficiency clinical presentation in order to focus on phenotypes that, in patients with myelodysplastic syndrome, may be suggestive of GATA2 deficiency. Moreover, due to the lack of clear guidelines, we performed an overview on literature data regarding management of GATA2-related myelodysplastic syndrome, in order to understand the best choice of treatment for these patients.

Abstract

Myelodysplastic syndromes (MDS) are hematopoietic disorders rare in childhood, often occurring in patients with inherited bone marrow failure syndromes or germinal predisposition syndromes. Among the latter, one of the most frequent involves the gene GATA binding protein 2 (GATA2), coding for a transcriptional regulator of hematopoiesis. The genetic lesion as well as the clinical phenotype are extremely variable; many patients present hematological malignancies, especially MDS with the possibility to evolve into acute myeloid leukemia. Variable immune dysfunction, especially resulting in B- and NK-cell lymphopenia, lead to severe infections, including generalized warts and mycobacterial infection. Defects of alveolar macrophages lead to pulmonary alveolar proteinosis through inadequate clearance of surfactant proteins. Currently, there are no clear guidelines for the monitoring and treatment of patients with GATA2 mutations. In patients with MDS, the only curative treatment is allogeneic hematopoietic stem cell transplantation (HSCT) that restores normal hematopoiesis preventing the progression to acute myeloid leukemia and clears long-standing infections. However, to date, the donor type, conditioning regimen, and the optimal time to proceed to HSCT, as well as the level of chimerism needed to reverse the phenotype, remain unclear highlighting the need for consensus guidelines.

Donor-derived myelodysplastic syndrome after allogeneic stem cell transplantation in a family with germline GATA2 mutation

Germline GATA2 heterozygous mutations were identified as complex immunodeficiency and hematological syndromes characterized by cytopenia (monocytes, B-cells, NK-cells), susceptibility to mycobacterium, fungus, or Epstein-Barr virus (EBV) infection, and myelodysplastic syndrome (MDS)/acute myelogenous leukemia (AML) development. Herein, we report a patient with AML who had a fatal infection after allogeneic hematopoietic stem cell transplantation (HSCT) due to impaired immune reconstitution associated with GATA2 mutation. A 15-year-old man was diagnosed with AML with monosomy 7. His family history was negative for immunodeficiency and hematological disorders. He attained complete remission after HSCT from an HLA-identical sister. Post-HSCT examinations performed 15 months later revealed pancytopenia, especially monocytopenia and the absence of B and NK cells, resulting in the occurrence of donor-type MDS. Twenty-one months after HSCT, he developed central nervous system aspergillosis and finally died of the disease. Two months later (24 months after PBSCT), the donor was diagnosed with persistent EBV infection accompanied by MDS with multilineage dysplasia. Genetic analysis of GATA2 revealed a novel heterozygous mutation (c.1023_1026dupCGCC) in both siblings. GATA2 mutations were highly prevalent among adolescent MDS/AML patients with monosomy 7. Therefore, the screening of GATA2 mutations in relatives is necessary when performing HSCT from a relative donor.

General Overview of Nontuberculous Mycobacteria Opportunistic Pathogens: Mycobacterium avium and Mycobacterium abscessus

Nontuberculous mycobacteria (NTM) are emerging human pathogens, causing a wide range of clinical diseases affecting individuals who are immunocompromised and who have underlying health conditions. NTM are ubiquitous in the environment, with certain species causing opportunistic infection in humans, including Mycobacterium avium and Mycobacterium abscessus. The incidence and prevalence of NTM infections are rising globally, especially in developed countries with declining incidence rates of M. tuberculosis infection. Mycobacterium avium, a slow-growing mycobacterium, is associated with Mycobacterium avium complex (MAC) infections that can cause chronic pulmonary disease, disseminated disease, as well as lymphadenitis. M. abscessus infections are considered one of the most antibiotic-resistant mycobacteria and are associated with pulmonary disease, especially cystic fibrosis, as well as contaminated traumatic skin wounds, postsurgical soft tissue infections, and healthcare-associated infections (HAI). Clinical manifestations of diseases depend on the interaction of the host’s immune response and the specific mycobacterial species. This review will give a general overview of the general characteristics, vulnerable populations most at risk, pathogenesis, treatment, and prevention for infections caused by Mycobacterium avium, in the context of MAC, and M. abscessus.

Allogeneic hematopoietic cell transplantation in the management of GATA2 deficiency and pulmonary alveolar proteinosis

Human hematopoiesis is critically dependent on the transcription factor GATA2. Patients with GATA2 deficiency typically present with myelodysplastic syndrome, reduced numbers of monocytes, NK cells and B cells, and/or opportunistic infections. Here, we present two families that harbor distinct GATA2 mutations with highly variable onset and course of disease. We discuss the use of allogeneic hematopoietic cell transplantation in these patients, especially as treatment for pulmonary alveolar proteinosis.

Connecting the Dots From Fever of Unknown Origin to Myelodysplastic Syndrome: GATA2 Haploinsufficiency

Leukemia-predisposing conditions, such as GATA2 haploinsufficiency, are known for their high penetrance and expressivity profiles. These disorders pose a difficult diagnostic challenge to even the most experienced clinician when they first present. We describe the case of a 17-year-old male presenting with features of nontuberculous mycobacterial infection, pulmonary fibrinoid granulomatous vasculitis, and myelodysplasia in the setting of a pathogenic GATA2 frameshift mutation confirmed by next-generation sequencing. The broad differential for GATA2 haploinsufficiency requires prompt recognition of key clinical features and laboratory abnormalities towards directing diagnosis and guiding appropriate and perhaps life-saving therapy.

C/EBPα and GATA-2 Mutations Induce Bilineage Acute Erythroid Leukemia through Transformation of a Neomorphic Neutrophil-Erythroid Progenitor

Acute erythroid leukemia (AEL) commonly involves both myeloid and erythroid lineage transformation. However, the mutations that cause AEL and the cell(s) that sustain the bilineage leukemia phenotype remain unknown. We here show that combined biallelic Cebpa and Gata2 zinc finger-1 (ZnF1) mutations cooperatively induce bilineage AEL, and that the major leukemia-initiating cell (LIC) population has a neutrophil-monocyte progenitor (NMP) phenotype. In pre-leukemic NMPs Cebpa and Gata2 mutations synergize by increasing erythroid transcription factor (TF) expression and erythroid TF chromatin access, respectively, thereby installing ectopic erythroid potential. This erythroid-permissive chromatin conformation is retained in bilineage LICs. These results demonstrate that synergistic transcriptional and epigenetic reprogramming by leukemia-initiating mutations can generate neomorphic pre-leukemic progenitors, defining the lineage identity of the resulting leukemia.

Transcriptional landscape of SARS-CoV-2 infection dismantles pathogenic pathways activated by the virus, proposes unique sex-specific differences and predicts tailored therapeutic strategies

The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) has posed a serious threat to global health. As no specific therapeutics are yet available to control disease evolution, more in-depth understanding of the pathogenic mechanisms induced by SARS-CoV-2 will help to characterize new targets for the management of COVID-19. The present study identified a specific set of biological pathways altered in primary human lung epithelium upon SARS-CoV-2 infection, and a comparison with SARS-CoV from the 2003 pandemic was studied. The transcriptomic profiles were also exploited as possible novel therapeutic targets, and anti-signature perturbation analysis predicted potential drugs to control disease progression. Among them, Mitogen-activated protein kinase kinase (MEK), serine-threonine kinase (AKT), mammalian target of rapamycin (mTOR) and I kappa B Kinase (IKK) inhibitors emerged as candidate drugs. Finally, sex-specific differences that may underlie the higher COVID-19 mortality in men are proposed.

Insights from Patients with Dendritic Cell Immunodeficiency

Dendritic Cells (DCs), derived from haematopoietic stem cells, are critical to the dynamic and balanced functioning of the intact immune system and are of great interest as vehicles of immunotherapy. Genetically modified mouse models have proved powerful tools to map DC development and function in vivo but human studies have previously relied heavily on in vitro systems. Human dendritic cell immunodeficiency, resulting from single gene mutations, offers new opportunities to dissect the role of human DCs in vivo, determine the genetic requirements for their development and map their haematopoietic differentiation pathways. This review will summarise the clinical phenotypes of mutations in GATA2, IRF8 and IKZF1 genes which result in global or subset specific dendritic cell deficiencies, discuss the functional consequences of these cytopenias and how these syndromes have informed our knowledge of DC differentiation and human haematopoiesis.

Advances in Understanding Human Genetic Variations That Influence Innate Immunity to Fungi

Fungi are ubiquitous. Yet, despite our frequent exposure to commensal fungi of the normal mammalian microbiota and environmental fungi, serious, systemic fungal infections are rare in the general population. Few, if any, fungi are obligate pathogens that rely on infection of mammalian hosts to complete their lifecycle; however, many fungal species are able to cause disease under select conditions. The distinction between fungal saprophyte, commensal, and pathogen is artificial and heavily determined by the ability of an individual host's immune system to limit infection. Dramatic examples of commensal fungi acting as opportunistic pathogens are seen in hosts that are immune compromised due to congenital or acquired immune deficiency. Genetic variants that lead to immunological susceptibility to fungi have long been sought and recognized. Decreased myeloperoxidase activity in neutrophils was first reported as a mechanism for susceptibility to Candida infection in 1969. The ability to detect genetic variants and mutations that lead to rare or subtle susceptibilities has improved with techniques such as single nucleotide polymorphism (SNP) microarrays, whole exome sequencing (WES), and whole genome sequencing (WGS). Still, these approaches have been limited by logistical considerations and cost, and they have been applied primarily to Mendelian impairments in anti-fungal responses. For example, loss-of-function mutations in CARD9 were discovered by studying an extended family with a history of fungal infection. While discovery of such mutations furthers the understanding of human antifungal immunity, major Mendelian susceptibility loci are unlikely to explain genetic disparities in the rate or severity of fungal infection on the population level. Recent work using unbiased techniques has revealed, for example, polygenic mechanisms contributing to candidiasis. Understanding the genetic underpinnings of susceptibility to fungal infections will be a powerful tool in the age of personalized medicine. Future application of this knowledge may enable targeted health interventions for susceptible individuals, and guide clinical decision making based on a patient's individual susceptibility profile.

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.

All-trans retinoic acid (ATRA)-induced TFEB expression is required for myeloid differentiation in acute promyelocytic leukemia (APL)

OBJECTIVE

In acute promyelocytic leukemia (APL), normal retinoid signaling is disrupted by an abnormal PML-RARα fusion oncoprotein, leading to a block in cell differentiation. Therapeutic concentrations of all-trans-retinoic acid (ATRA) can restore retinoid-induced transcription and promote degradation of the PML-RARα protein. Autophagy is a catabolic pathway that utilizes lysosomal machinery to degrade intracellular material and facilitate cellular re-modeling. Recent studies have identified autophagy as an integral component of ATRA-induced myeloid differentiation.

METHODS

As the molecular communication between retinoid signaling and the autophagy pathway is not defined, we performed RNA sequencing of NB4 APL cells treated with ATRA and examined autophagy-related transcripts.

RESULTS

ATRA altered the expression of >80 known autophagy-related transcripts, including the key transcriptional regulator of autophagy and lysosomal biogenesis, TFEB (11.5-fold increase). Induction of TFEB and its transcriptional target, sequestosome 1 (SQSTM1, p62), is reduced in ATRA-resistant NB4R cells compared to NB4 cells. TFEB knockdown in NB4 cells alters the expression of transcriptional targets of TFEB and reduces CD11b transcript levels in response to ATRA.

CONCLUSIONS

We show for the first time that TFEB plays an important role in ATRA-induced autophagy during myeloid differentiation and that autophagy induction potentiates leukemic cell differentiation (Note: this study includes data obtained from NCT00195156, https://clinicaltrials.gov/show/NCT00195156).

Combining gene variants with clinical characteristics improves outcome prediction in Chinese patients with myelodysplastic syndromes

Genetic variants have been identified in the majority of myelodysplastic syndromes (MDS) patients and have considerably influenced the diagnosis, classification, risk stratification and treatment of MDS. To explore the prognostic significance of genomic variants and build a new prognostic scoring model, we performed next-generation sequencing of 51 known genes in 499 Chinese patients with MDS. Ultimately, the TP53, GATA2, DNMT3A, age and the revised International Prognostic Scoring System (IPSS-R) risk stratification were included in a new Cox model and divided into three prognostic categories, and had a better prediction of overall survival. The C-index of the new prognostic scoring model (0.772) was clearly better than IPSS-R risk stratification (0.717), which was validated in 163 cases. Moreover, the new model was also suitable for the prediction of OS for patients undergoing allogeneic hematopoietic stem cell transplantation. The inclusion of genomic variants and age into the IPSS-R could improve prognostic algorithms for MDS patients.

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.

Heterogeneity of human bone marrow and blood natural killer cells defined by single-cell transcriptome

Natural killer (NK) cells are critical to both innate and adaptive immunity. However, the development and heterogeneity of human NK cells are yet to be fully defined. Using single-cell RNA-sequencing technology, here we identify distinct NK populations in human bone marrow and blood, including one population expressing higher levels of immediate early genes indicative of a homeostatic activation. Functionally matured NK cells with high expression of CX3CR1, HAVCR2 (TIM-3), and ZEB2 represents terminally differentiated status with the unique transcriptional profile. Transcriptomic and pseudotime analyses identify a transitional population between CD56^bright and CD56^dim NK cells. Finally, a donor with GATA2^T354M mutation exhibits reduced percentage of CD56^bright NK cells with altered transcriptome and elevated cell death. These data expand our understanding of the heterogeneity and development of human NK cells.

Natural killer (NK) cells are important innate immune cells with diverse functions. Here the authors use single-cell RNA-sequencing of purified human bone marrow and peripheral blood NK cells to define five populations of NK cells with distinct transcriptomic profile to further our understanding of NK development and heterogeneity.

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.

The genetics of human hematopoiesis and its disruption in disease

Hematopoiesis, or the process of blood cell production, is a paradigm of multi-lineage cellular differentiation that has been extensively studied, yet in many aspects remains incompletely understood. Nearly all clinically measured hematopoietic traits exhibit extensive variation and are highly heritable, underscoring the importance of genetic variation in these processes. This review explores how human genetics have illuminated our understanding of hematopoiesis in health and disease. The study of rare mutations in blood and immune disorders has elucidated novel roles for regulators of hematopoiesis and uncovered numerous important molecular pathways, as seen through examples such as Diamond-Blackfan anemia and the GATA2 deficiency syndromes. Additionally, population studies of common genetic variation have revealed mechanisms by which human hematopoiesis can be modulated. We discuss advances in functionally characterizing common variants associated with blood cell traits and discuss therapeutic insights, such as the discovery of BCL11A as a modulator of fetal hemoglobin expression. Finally, as genetic techniques continue to evolve, we discuss the prospects, challenges, and unanswered questions that lie ahead in this burgeoning field.

GATA2 Deficiency: Early Identification for Improved Clinical Outcomes

BACKGROUND

Patients with GATA2 deficiency present with nontuberculous mycobacterial infections, severe viral infections (particularly refractory human papillomavirus disease), lymphedema, myelodysplastic syndrome (MDS), and acute myeloid leukemia. Patients with GATA2 deficiency who undergo allogeneic hematopoietic stem cell transplantation prior to the development of life-threatening infections or cytogenetic abnormalities may have optimal clinical outcomes.

OBJECTIVES

The aim of this article is to determine ways in which oncology nurses can identify GATA2 deficiency in patients early and optimize treatment decisions.

METHODS

A case study is presented of a 33-year-old man with recurrent infections and MDS and his two sons, all of whom were found to have the same GATA2 mutation.

FINDINGS

Oncology nurses play an important role in early detection and identification by interviewing patients and obtaining a complete and thorough family history.

GATA2 mutation underlies hemophagocytic lymphohistiocytosis in an adult with primary cytomegalovirus infection

We report a case of a 27-year old woman with persistent fever and pancytopenia who had multiple episodes of a hemophagocytic lymphohistiocytosis (HLH) like condition. The criterion for HLH was satisfied; primary cytomegalovirus (CMV) infection was identified as the cause. Further examination revealed a GATA binding protein 2 mutation. Reports of GATAs deficiency presenting with HLH after primary CMV infection is very limited. As early recognition and diagnosis will improve patients' outcomes, internists and infectious disease specialists should be aware of this disease.

The independent prognostic impact of the GATA2 pioneering factor is restricted to ERG-negative prostate cancer

GATA2 is a pioneering transcription factor governing androgen receptor expression and signaling in prostate cells. To understand the prognostic potential of GATA2 assessment in prostate cancer, we analyzed nuclear GATA2 expression on an annotated tissue microarray with 12,427 prostate cancer samples. Normal prostate glands were negative to weakly positive. GATA2 staining was found in almost all prostate cancers (95%). Strong GATA2 staining was linked to advanced tumor stage, high classical and quantitative Gleason grade (p < 0.0001 each), positive nodal stage (p = 0.0116), and early biochemical recurrence (p < 0.0001). GATA2 was linked to ERG-fusion-type cancers, with strong GATA2 staining in 29% of ERG-negative and 53% of ERG-positive cancers (p < 0.0001). Separate calculations in 3854 cancers with and 4768 cancers without TMPRSS2:ERG fusion revealed that these associations with tumor phenotype and patient outcome were largely driven by the subset of ERG-negative tumors. GATA2 expression was further linked to androgen receptor expression: Only 8% of androgen receptor-negative, but 56% of strongly androgen receptor expressing cancers had strong GATA2 expression (p < 0.0001). In conclusion, the results of our study demonstrate that increasing GATA2 levels are linked to prostate cancer progression and aggressiveness. The prognostic value of GATA2 is remarkable in ERG-negative cancers. However, the upregulation of GATA2 in ERG-positive cancers makes it unsuitable as a prognostic marker in this patient subset.

The Ontogeny of Monocyte Subsets

Classical and non-classical monocytes, and the macrophages and monocyte-derived dendritic cells they produce, play key roles in host defense against pathogens, immune regulation, tissue repair and many other processes throughout the body. Recent studies have revealed previously unappreciated heterogeneity among monocytes that may explain this functional diversity, but our understanding of mechanisms controlling the functional programming of distinct monocyte subsets remains incomplete. Resolving monocyte heterogeneity and understanding how their functional identity is determined holds great promise for therapeutic immune modulation. In this review, we examine how monocyte origins and developmental influences shape the phenotypic and functional characteristics of monocyte subsets during homeostasis and in the context of infection, inflammation, and cancer. We consider how extrinsic signals and transcriptional regulators impact monocyte production and functional programming, as well as the influence of epigenetic and metabolic mechanisms. We also examine the evidence that functionally distinct monocyte subsets are produced via different developmental pathways during homeostasis and that inflammatory stimuli differentially target progenitors during an emergency response. We highlight the need for a more comprehensive understanding of the relationship between monocyte ontogeny and heterogeneity, including multiparametric single-cell profiling and functional analyses. Studies defining mechanisms of monocyte subset production and maintenance of unique monocyte identities have the potential to facilitate the design of therapeutic interventions to target specific monocyte subsets in a variety of disease contexts, including infectious and inflammatory diseases, cancer, and aging.