GATA2 Deficiency Research Articles

Inherited Predispositions to Myeloid Neoplasms: Pathogenesis and Clinical Implications.

Myeloid neoplasms with and without preexisting platelet disorders frequently develop in association with an underlying germline predisposition. Germline alterations affecting ANKRD26, CEBPA, DDX41, ETV6, and RUNX1 are associated with nonsyndromic predisposition to the development of myeloid neoplasms including acute myeloid leukemia and myelodysplastic syndrome. However, germline predisposition to myeloid neoplasms is also associated with a wide range of other syndromes, including SAMD9/9L associated predisposition, GATA2 deficiency, RASopathies, ribosomopathies, telomere biology disorders, Fanconi anemia, severe congenital neutropenia, Down syndrome, and others. In the fifth edition of the World Health Organization (WHO) series on the classification of tumors of hematopoietic and lymphoid tissues, myeloid neoplasms associated with germline predisposition have been recognized as a separate entity. Here, we review several disorders from this WHO entity as well as other related conditions with an emphasis on the molecular pathogenesis of disease and accompanying somatic alterations. Finally, we provide an overview of establishing the molecular diagnosis of these germline genetic conditions and general recommendations for screening and management of the associated hematologic conditions.

Renegotiation, uncertainty, imagination: Assemblage perspectives on reproductive and family planning with an Inborn Error of immunity

Advances within the new genetics expand our understanding of the scope and presentation of inherited conditions, particularly to include incompletely penetrant and variably expressive conditions. These features can complicate patients’ reproductive and family planning processes, in part because they expand the possibilities of life with an inherited condition. Despite many inquiries into reproductive planning with an inherited condition, accounts of experiential knowledge and reproductive planning fail to adequately describe the uncertainties experienced by people living with incompletely penetrant and variably expressive conditions. To address this gap, we conducted a qualitative, cross-sectional study using assemblage theory to characterize the impacts of experiential knowledge on reproductive planning for individuals living with Inborn Errors of Immunity (IEI) that exhibit incomplete penetrance and variable expressivity.Eligible participants were between ages 18 and 48, with a diagnosis of either GATA2 deficiency, PIK3CD gain-of-function disorder, or CTLA4 deficiency. Using an abductive thematic approach, attention was paid to the people, ideas, and non-human objects embedded within participants’ accounts of disease experience and reproductive planning. Organized around the objects of genetic diagnosis, the body, and hypothetical children, this analysis illustrates how disease can be conceptualized as an assemblage of human and non-human objects which provoke numerous actions and affective engagements in reproductive planning. These engagements include renegotiation, uncertainty, and imagination. By emphasizing the distribution of agency and action across systems, processes, and relationships, assemblage theory invites novel ways of understanding the role of experiential knowledge on reproductive planning.

Genetic predisposition to myelodysplastic syndrome: Genetic counseling and transplant implications

The development of myelodysplastic syndromes (MDS) is influenced by various genetic predispositions. Several important genes contribute to disease susceptibility. This paper explores common genetic predisposition genes in MDS, including DDX41, CEBPA, and SAMD9/SAMD9L, which are linked to hereditary conditions presenting diagnostic and clinical challenges. It delves into hereditary conditions that affect platelet production and count, such as RUNX1, ETV6, and ANKRD26, detailing their clinical features and how they contribute to an increased risk of MDS. The discussion extends to additional genetic syndromes like GATA2 deficiency, telomere biology disorders, Fanconi anemia, and Li-Fraumeni syndrome, along with new findings on genes like ERG that offer new insights into disease etiology. The importance of genetic counseling in MDS is underscored, outlining its goals, methods for evaluating family history, risk assessment, and the ethical considerations involved. Furthermore, the role of hematopoietic cell transplantation in managing MDS, particularly in patients with germline syndromes, is reviewed, emphasizing the need for optimal donor selection and personalized treatment approaches. This comprehensive overview illustrates the critical role of genetic factors in MDS and highlights the need for continued research and tailored clinical practices to improve patient outcomes.

AYA With GATA2 Deficiency Syndrome With Evolving Myeloid Neoplasia: Case Presentation

AYA With GATA2 Deficiency Syndrome With Evolving Myeloid Neoplasia: Case Presentation

Long-term outcome after allogeneic stem cell transplantation for GATA2 deficiency: An analysis of 67 adults and children from France and Belgium.

Modalities and timing of haematopoietic stem cell transplant (HSCT) in patients with GATA2 deficiency are still subject to debate. On June 2022, 67 patients (median age 20.6 years) underwent a first allogeneic HSCT among 21 centres. Indications for HSCT were myelodysplastic syndrome (MDS) ≤5% blasts ± immunodeficiency (66%), MDS >5% blasts (15%), acute myeloid leukaemia (19%). Conditioning regimen was myeloablative in 85% and anti-thymocyte globulins were used in 67%. The cumulative incidence (CInc) of acute graft versus host disease (GvHD) grade II-IV and III-IV at day 100 were 42% and 13%, and CInc of chronic and extensive chronic GvHD at 2 years were 42% and 23%. CInc of relapses was 3% and 11% at 1 and 5 years. Overall survival (OS) at 1 and 5 years was 83% and 72% (median follow-up 5.6 years). The factors associated with worse OS in multivariable analysis were the year of HSCT, a history of excess blasts before transplant and peripheral blood stem cell (PBSC) grafts. Age at HSCT, non-myeloablative conditioning and PBSC grafts were associated with increased non-relapse mortality. In conclusion, bone marrow monitoring to identify clonal evolution and perform HSCT before the appearance of excess blast is mandatory.

Prognostic significance of GATA2 in patients with MDS/AML: a systematic review and meta-analysis.

GATA2 deficiency syndrome is a heterogeneous disorder characterized by a high risk of developing myelodysplastic syndrome (MDS)/acute myeloid leukaemia (AML). We conducted a meta-analysis of the literature to explore the prognostic significance of GATA2 mutations in patients diagnosed with MDS/AML, as previous studies have yielded conflicting findings regarding the impact of GATA2 mutations on patient outcomes. We conducted a comprehensive literature search of databases such as PubMed, Embase, the Cochrane Library, and the Web of Science to obtain studies on the prognostic significance of GATA2 mutations in patients with MDS/AML that were published through January 2024. We extracted the hazard ratio (HR) and 95% confidence interval (CI) for overall survival (OS), disease-free survival (DFS), and event-free survival (EFS). The meta-analysis was conducted by choosing either a fixed-effect model or a random-effect model, depending on the variability observed among the studies. A total of 13 cohort studies were included in the final meta-analysis, including 2714 patients with MDS, of whom 644 had GATA2 mutations. The results revealed that GATA2 mutations had an adverse impact on OS (HR = 1.54, 95% CI = 1.08-2.18, P = 0.02) and EFS (HR = 1.32, 95% CI = 1.01-1.72, P = 0.04), but no significant effect on DFS (HR = 1.21, 95% CI = 0.89-1.64, P = 0.23). GATA2 mutations were associated with a significantly shorter OS in MDS patients (HR = 2.56, 95% CI = 1.42-4.06, P = 0.002) but not in AML patients (HR = 1.08, 95% CI = 0.92-1.26, P = 0.37). Our meta-analysis revealed that GATA2 mutations are associated with unfavourable outcomes in patients with MDS/AML. Furthermore, patients harbouring these mutations should be prioritized for aggressive therapeutic interventions.

GATA2 deficiency syndrome: A compensatory mechanism gone awry?

In their paper, using zebrafish models, Gioacchino etal. have demonstrated the GATA2 haploinsufficiency, the genetic hallmark of GATA2 deficiency syndrome, promotes erythroid and myeloid cytopenia, and have discovered a self-regulatory mechanism to compensate GATA2 levels and protein function. Commentary on: Gioacchino etal. GATA2 heterozygosity causes an epigenetic feedback mechanism resulting in myeloid and erythroid dysplasia. Br J Haematol 2024;205:580-593.

Clinical Profile of Adults with Inherited Bone Marrow Failure Syndromes: Results of an Ambispective Clinical Single-Center Study

BACKGROUND. Inherited bone marrow failure syndromes (IBMFS) is a heterogenous group of rare genetically determined diseases with variable hematologic and nonhematologic manifestations. The implementation of highly specific methods of genetic diagnosis advanced the understanding of IBMFS and allowed its application also beyond pediatrics. That presupposes an awareness of clinical features and reference points for recognizing IBMFS in adults. AIM. To describe the clinical profile of adult IBMFS patients. MATERIALS & METHODS. This ambispective single-center study enrolled 35 patients (10 women and 25 men) with IBMFS. Patients were aged 18–51 years (median 26 years). The following IBMFS were identified: congenital dyskeratosis (n = 10; 28 %), Diamond-Blackfan anemia (n = 9; 26 %), Fanconi anemia (n = 7; 20 %), GATA2 deficiency (n = 3; 8 %), Shwachman-Diamond syndrome (n = 1; 3 %), GATA2 deficiency (n = 1; 3 %), amegakaryocytic thrombocytopenia (n = 1; 3 %), bone marrow failure syndrome type 3 (n = 1; 3 %), severe congenital neutropenia (n = 1; 3 %), bone marrow failure with SAMD9 mutation (n = 1; 3 %). These diseases were analyzed in terms of hematologic and nonhematologic manifestations as well as main diagnosis stages and factors that contribute to recognizing IBMFS. RESULTS. Monolinear cytopenia, bilinear cytopenia, and pancytopenia were identified at hematologic onset in 18 (52 %), 6 (17 %), and 11 (31 %) patients, respectively. The median age of patients by hematologic onset was 15 years (range 0–43 years), in 14 (40 %) patients cytopenia was newly diagnosed at the age of > 18 years. In 23 (63 %) patients hypocellular bone marrow was reported, 7 (20 %) and 5 (14 %) patients had pure red cell aplasia and multilineage myelodysplasia, respectively. Chromosomal aberrations were identified in 2 patients. Paroxysmal nocturnal hemoglobinuria clone was detected in none of 27 examined patients. In 12 (34 %) patients, the criteria for non-severe aplastic anemia were met. Temporary partial or complete spontaneous hematologic recovery was observed in 6 (17 %) patients. Abnormalities with partial or complete organ dysfunctions were identified in 14 patients, whereas all patients showed minor congenital defects. All 7 Fanconi anemia patients and 9 out of 10 congenital dyskeratosis patients demonstrated organ damage specific to these diseases. Family history predominantly showing malignant neoplasms in relatives was reported in 15 (43 %) patients. Initial hematological examination yielded suspect of IBMFS in 12 (34 %) patients with the median time to diagnosis of 6 months. In 23 (66 %) patients, hematologic defects with cytopenia were erroneously accounted for by various acquired diseases, which led to a delayed correct diagnosis (median 7 years). The key factors in suspecting IBMFS were organ abnormalities and positive family history. The IBMFS diagnosis was verified by the next-generation sequencing (NGS) in 29 (83 %) patients and by other specific methods in 4 (11 %) patients. In 2 patients, the diagnosis was established on the basis of complete clinical criteria alone. CONCLUSION. IBMFS is a matter of current concern and a difficult-to-recognize clinical challenge in adult hematology patients. Differential diagnosis of acquired and congenital bone marrow failure needs to be performed irrespective of patient’s age. A detailed physical examination of patients, family history, and critical analysis of clinical profile and disease course allow for early suspicion of IBMFS. Suspected IBMFS is an indication for referral of patients to specialized centers and performing genetic diagnostics including NGS.

GATA2 deficiency: a mystery myelodysplasia

SummaryGATA2 deficiency, arising from mutations in the GATA2 gene, is a rare genetic disorder with profound implications for hematopoiesis, immune function, and overall health. This case report provides a comprehensive exploration of the clinical manifestations, diagnostic challenges, and management of GATA2 deficiency, emphasizing the importance of early recognition and specialized care. A 55-year-old female presented with a complex clinical presentation that evolved from myalgias into a syndrome of symptoms, including fever, chest pain, dyspnea, and profound weakness. The diagnostic journey involved recurrent admissions, a delay in diagnosis, and the consideration of various differential diagnoses, reflecting the elusive nature of GATA2 deficiency. Pulmonary involvement, hematologic abnormalities, and the patient’s transfer to a specialized center further highlighted the multifaceted aspects of this disorder. This case underscores the diagnostic challenges and clinical heterogeneity of GATA2 deficiency. It emphasizes the need for a high index of suspicion, early diagnosis, and specialized care. The elusive nature of the disorder, pulmonary involvement, and the emergence of hematologic abnormalities exemplify the complexity of GATA2 deficiency. The case report advocates for enhanced awareness, early detection, and the importance of specialized expertise in managing this rare genetic condition.

14 Unmasking the Mimic: Cytomegalovirus Pneumonia masquerading as CVID unravels as GATA2 Deficiency with Two Unique Pathological Mutations

14 Unmasking the Mimic: Cytomegalovirus Pneumonia masquerading as CVID unravels as GATA2 Deficiency with Two Unique Pathological Mutations

Allogeneic hematopoietic stem cell transplantation in a patient with MonoMAC syndrome and hematopoietic dysplasia which was induced by GATA2 deficiency: a case report and literature review

A retrospective analysis was conducted on a MonoMAC syndrome case admitted in October 2022 to the First Affiliated Hospital of Zhejiang University School of Medicine. The patient, a 16-year-old female with a history of persistent monocytopenia and mild anemia for several years, experienced recurrent symptoms of cough, expectoration, and fever, leading to multiple visits to the hospital. The diagnosis of MonoMAC syndrome was confirmed through comprehensive assessments including routine blood tests, pathogen metagenomic sequencing, lung and bone marrow biopsies, and next-generation sequencing of peripheral blood. The patient underwent haploidentical hematopoietic stem cell transplantation, with a smooth course of transplantation, achieving neutrophil engraftment on + 16 d and platelet engraftment on + 17 d, eventually restoring normal monocyte and NK cell counts. MonoMAC syndrome patients often initially present with infectious symptoms, and the diagnosis can be established based on significant monocytopenia in routine blood tests, history of non-tuberculous mycobacterial infections, and GATA2 germline mutations. Allogeneic hematopoietic stem cell transplantation may be required for some patients to improve their prognosis.

Pathogenic GATA2 genetic variants utilize an obligate enhancer mechanism to distort a multilineage differentiation program

Mutations in genes encoding transcription factors inactivate or generate ectopic activities to instigate pathogenesis. By disrupting hematopoietic stem/progenitor cells, GATA2 germline variants create a bone marrow failure and leukemia predisposition, GATA2 deficiency syndrome, yet mechanisms underlying the complex phenotypic constellation are unresolved. We used a GATA2-deficient progenitor rescue system to analyze how genetic variation influences GATA2 functions. Pathogenic variants impaired, without abrogating, GATA2-dependent transcriptional regulation. Variants promoted eosinophil and repressed monocytic differentiation without regulating mast cell and erythroid differentiation. While GATA2 and T354M required the DNA-binding C-terminal zinc finger, T354M disproportionately required the N-terminal finger and N terminus. GATA2 and T354M activated a CCAAT/Enhancer Binding Protein-ε (C/EBPε) enhancer, creating a feedforward loop operating with the T-cell Acute Lymphocyte Leukemia-1 (TAL1) transcription factor. Elevating C/EBPε partially normalized hematopoietic defects of GATA2-deficient progenitors. Thus, pathogenic germline variation discriminatively spares or compromises transcription factor attributes, and retaining an obligate enhancer mechanism distorts a multilineage differentiation program.

Susceptibility to mycobacterial infection in VEXAS syndrome.

VEXAS is a recently described acquired auto-inflammatory and hematologic syndrome caused by somatic mutations in UBA1. To date, VEXAS is not a recognized cause of acquired immunodeficiency. Two of our 10 VEXAS patients developed a disseminated Mycobacterium avium infection. To shed light on this observation, we retrospectively studied all patients with disseminated non-tuberculous mycobacterial infections (NTMi) seen at our institution over 13 years. Inclusion criteria were a positive blood/bone marrow culture, or 2 positive cultures from distinct sites, or one positive culture with 2 involved sites. patient 1 presented with fever, rash, orbital cellulitis and lung infiltrates. Patient 2 presented with fever and purpura. In both cases, Mycobacterium avium was identified on bone marrow culture. Twenty cases of disseminated NTMi were reviewed. Among 11 HIV-negative patients, three had chronic immune-mediated disease; three had untreated myeloid neoplasm; two had VEXAS; one had undergone kidney transplantation; one had GATA-2 deficiency; and one had no identified aetiology. None had lymphoid neoplasia or had undergone bone marrow transplantation. HIV-negative cases had higher CD4 counts than HIV-positive patients (median CD4: 515/mm3 vs 38/mm3, p< 0.001). Monocytopenia was present in seven cases. At 2 years, six patients had died, including both VEXAS patients. VEXAS patients have an intrinsic susceptibility to disseminated NTMi, which may result from monocytic dysfunction. NTMi can mimic VEXAS flare. Clinicians should maintain a high suspicion for opportunistic infections before escalating immunosuppressive therapy. Further studies are needed to confirm and better decipher the herein reported observations.

One GATA2 three… a case series of hematologic presentations in GATA2 deficiency

One GATA2 three… a case series of hematologic presentations in GATA2 deficiency

The different faces of GATA2 deficiency: implications for therapy and surveillance.

GATA2 deficiency is one of the most common genetic predispositions to pediatric myelodysplastic syndrome (MDS) in children and adolescents. The wide spectrum of disease comprises, among others, hematological, immunological and pulmonary manifestations, as well as occasionally distinct organ anomalies. Due to the elevated risk of progression, nearly all individuals with GATA2-related MDS eventually undergo a hematopoietic stem cell transplantation (HSCT) at some point in their lives. Nevertheless, the optimal timing, method, and even the indication for HSCT in certain cases are still matter of debate and warrant further research. In this article, we report five patients with different hematological and immunological manifestations of GATA2 deficiency ranging from immunodeficiency and refractory cytopenia of childhood without chromosomal aberrations to relapsed MDS-related acute myeloid leukemia. We discuss the adopted strategies, including intensity of surveillance, indication and timing of HSCT, based on morphological, clinical and molecular markers, as well as individual patient needs. We conclude that a better characterization of the natural disease course, a better understanding of the prognostic significance of somatic aberrations and a thorough evaluation of patients´ perspectives and preferences are required to achieve a personalized approach aimed at improving the care of these patients.

Genetic Characteristics of Patients with Young-Onset Myelodysplastic Neoplasms.

Myelodysplastic neoplasm (MDS) is a heterogeneous group of myeloid neoplasms affected by germline and somatic genetic alterations. The incidence of MDS increases with age but rarely occurs at a young age. We investigated the germline and somatic genetic alterations of Korean patients with young-onset MDS (<40 years). Among the thirty-one patients, five (16.1%) had causative germline variants predisposing them to myeloid neoplasms (three with GATA2 variants and one each with PGM3 and ETV variants). We found that PGM3 deficiency, a subtype of severe immunodeficiency, predisposes patients to MDS. Somatic mutations were identified in 14 patients (45.2%), with lower rates in patients aged < 20 years (11.1%). Nine (29%) patients had U2AF1 S34F/Y mutations, and patients with U2AF1 mutations showed significantly worse progression-free survival (p < 0.001) and overall survival (p = 0.006) than those without U2AF1 mutations. A UBA1 M41T mutation that causes VEXAS syndrome was identified in a male patient. In conclusion, a germline predisposition to myeloid neoplasms occurred in ~16% of young-onset MDS patients and was largely associated with primary immunodeficiencies, including GATA2 deficiency. Furthermore, the high frequency of somatic U2AF1 mutations in patients with young-onset MDS suggests the presence of a distinct MDS subtype.

Maladaptive Somatic Rescue in FLT3 Mutations of Suspected Germline Nature

Somatic genetic rescue (SGR) is a very rare process in which the occurrence of a somatic genetic event offsets the consequences of a germline (GL) mutation resulting in genetic mosaicism and, in some cases, in a milder disease phenotype 1. Acquired somatic mutations may be adaptive by countering the negative effects of the primary mutation ( e.g., improving hematopoiesis) or maladaptive by overcorrecting the initial impairment causing a different, possibly opposite, disease phenotype ( e.g., leading to the development of a myeloid malignancy) 2. Exemplary cases of the latter scenario are mainly represented by severe congenital neutropenia (SCN) cases developing AML as consequence of somatic CSF3R mutations 3 and, sporadically, by adaptive SGR in the context of germline GATA2 and secondary acquisition of somatic GATA2 mutation, counterbalancing the germline effect 4. Although SGR has been functionally demonstrated in these two above mentioned cases, given the molecular heterogeneity of myeloid neoplasia (MN) and the rarity of such genetic events, one can suspect that, in various clinical contexts, any mutation in any gene could be the SG rescuer. During our clinical experience, we encountered a case of a 57yo. woman with newly diagnosed aplastic anemia (AA) who was found to harbor a rare germline FLT3R311W mutation (VAF 50%; predicted to be a loss-of-function/hypomorphic alteration; Fig1) who subsequently evolved to MDS with monosomy 7. Coexisting somatic hits included non RUNT-homology domain, RUNX1P398L mutation (VAF 19%). Ultimately, the patient progressed to AML with emergence of a FLT3D825V (VAF 14%) and a NRASG13D (24%) lesions. In this case carrying GL FLT3 variant, biallelic somatic FLT3 mutation may represent maladaptive SGR. Therefore, we reviewed NGS sequencing results of 5,308 patients with MN and found three other suspected cases harboring GL variants in FLT3 gene, which inspired further investigations. In total we identified 3 additional cases (total of 4/5308 screened patients and among 248 somatic FLT3 mutations. Interestingly, the other case GL FLT3A680T occurred in a patient with AA (35yo.) who subsequently progressed to MDS and AML and acquired somatic NPM1L258fs, PTPN11 A72V, WT1 A365fs and most importantly, a somatic CSF3RL619S . The latter may represent an illustrative case of SGR, in analogy to AML developing in the context of SCN. In addition, 2 other cases with MDS or MDS/MPN were identified both presenting with cytopenia. A 53yo. woman diagnosed with MDS/MPN and GL FLT3L262F (gnomAD: 0.00000399) with a compound heterozygous somatic JAK2V617F mutation, again possibly serving as maladaptive clonal SGR event. Finally, we have identified a GL FLT3A291P mutation (VAF 60%, gnomAD frequency: 1.59×10-5) in a 58yo. man who eventually developed AML. In sum, similar to other phosphotyrosine receptor kinases (PTRKs) such as CSF3R, somatic FLT3 mutations may in rare biallelic cases correspond to SGR events of hypomorphic GL mutation or alternatively but not exclusively somatic mutations in other PTRK could evolve to reveal the GL FLT3 deficiency. Indeed, in another abstract by our group (Abstract#187151) we show that somatic FLT3 mutations can accompany GL variants in CSF3R, CSF2RB, and CSF1R. References 1 Revy P, Kannengiesser C, Fischer A. Somatic genetic rescue in Mendelian haematopoietic diseases. Nat Rev Genet. 2019 Oct;20(10):582-598. 2 Kennedy AL, Shimamura A. Genetic predisposition to MDS: clinical features and clonal evolution. Blood. 2019 Mar 7;133(10):1071-1085. 3 Germeshausen M, Kratz CP, Ballmaier M, Welte K. RAS and CSF3R mutations in severe congenital neutropenia. Blood. 2009 Oct 15;114(16):3504-5. 4 Catto LFB, Borges G, Pinto AL, Clé DV, Chahud F, Santana BA, Donaires FS, Calado RT. Somatic genetic rescue in hematopoietic cells in GATA2 deficiency.

Noncoding GATA2 Genetic Variation As a Determinant of Hematopoietic Stem/Progenitor Cell Activity and Mobilization Efficiency

Germlinecoding and enhancer variants within the hematopoietic regulator GATA2 create a bone marrow failure and leukemia predisposition (Soukup and Bresnick, 2020). We generated a mouse model of GATA2 deficiency syndrome by engineering mice with a single-nucleotide variant in an intronic enhancer (+9.5) from GATA2 deficiency patients combined with deletion of the enhancer from the second allele (compound heterozygous; CH). This system models patients harboring a germline pathogenic allele accompanied by epigenetic silencing of the normal allele. Unlike homozygous Gata2 coding or regulatory deletions that are embryonic lethal, CH represents a unique system to analyze postnatal GATA2 function. We demonstrated that adult germline Gata2 variation alters steady-state HSPCs, blocks HSPC expansion and differentiation upon chemotherapy, attenuates long-term repopulating activity following bone marrow transplantation, leads to bone marrow failure following chronic inflammation by the viral mimetic polyI:C, alters HSPC response to the bacterial cell wall component LPS and attenuates HSPC mobilization in response to granulocyte colony stimulating factor (G-CSF) (Soukup et al., 2019, Soukup et al., 2021). As short-term G-CSF treatment induces HSPC metabolic gene signatures (Fast et al., 2021) and expansion and cell cycle entry (Schuettpelz et al., 2014), and CH have decreased MPPs (LSKCD150 -CD48 -) and common myeloid progenitors (CMPs) (Lin −Sca1 −Kit +FcγR −CD34 +) (Soukup et al., 2021), we asked if mobilization defects reflected decreased functional HSPCs in bone marrow. CH had 2.2-fold fewer colony forming units (CFU) from bone marrow (p = 0.007) than wild type (WT), reflecting a paucity of functional HSPCs. 16 hours following a single G-CSF dose, WT bone marrow immunophenotypic HSCs (LSKCD150 +CD48 -) and MPPs expanded 1.8-fold (p = 0.001 and 0.01, respectively); CH HSCs and MPPs were unchanged. CH led to decreased HSPCs and failed to induce rapid HSPC expansion post-G-CSF. We tested whether Gata2 variation impairs mobilization in response to different stimuli, or if select pathways are impacted via disrupting the CXCR4/CXCL12 chemokine axis with the CXCR4 antagonist plerixafor, stromal/neutrophil CXCR2 activation with rhIL-8, or VLA-4/VCAM1 binding with VLA-4 inhibitor BIO5192. IL-8 or BIO5192 resulted in 3.9- and 2.2-fold increased WT CFU, respectively (p &amp;lt; 0.0001 and 0.0014) without altering CH CFU. By contrast, mobilization with plerixafor resulted in a 4.3-fold increase in WT CFU (p &amp;lt; 0.0001) and 4.5-fold increase in CH CFU (p = 0.004). Targeting these pathways collectively with G-CSF was insufficient to restore normal mobilization in CH. Competitive transplantations with peripheral blood revealed G-CSF + plerixafor increased WT donor-derived hematopoiesis 24- and 20-fold at 8 and 12 weeks, respectively, versus vehicle control. Treatment of CH did not increase donor-derived contributions. Since GATA2 deficiency syndrome and somatic GATA2 variation involve heterozygous alleles, we tested whether monoallelic +9.5 Ets motif variation disrupts mobilization. G-CSF increased CFU 28.5-fold (p &amp;lt; 0.0001) relative to vehicle-treated WT. Mobilization of Gata2 Ets +/- HSPCs were reduced significantly (p = 0.003). CH variation severely disrupted mobilization, with 7.3-fold fewer CFU than Gata2 Ets +/- (p = 0.02). Synergistic G-CSF/plerixafor treatment increased CFU 89-fold in WT versus untreated (p &amp;lt; 0.0001), and Gata2 Ets +/- mobilization was reduced (p = 0.006) and not improved relative to Gata2 Ets -/- or CH, resembling G-CSF/BIO5192. Thus, Gata2 heterozygosity impaired G-CSF-induced HSPC mobilization with all regimens. Although GATA2 noncoding variation is not commonly evaluated, analysis of human data will be performed to assess relationships between variation and poor mobilization outcomes. Gata2 variation depletes functional HSPCs in the bone marrow, reducing the available HSPCs to mobilize and rendering most mobilization regimens inefficient. Ongoing studies are elucidating molecular mechanisms underlying the mobilization blockade. Our mobilization-defective system offers unique utility for elucidating fundamental HSPC mechanisms e.g., in the context of additional environmental and/or genetic insults. Future knowledge linking functionality of mobilization regimens in these contexts may unveil insights into mechanisms operational in poor mobilizers.

2701. Mycobacterial Immune Reconstitution Inflammatory Syndrome Following Hematopoietic Cell Transplantation for GATA2 Deficiency

Abstract Background Immune reconstitution inflammatory syndrome (IRIS) was first described in patients with HIV and opportunistic infections starting antiretroviral therapy, but may be seen following hematopoietic cell transplantation (HCT) in patients with pre-existing infections. GATA2 deficiency is a genetic disorder with a marked susceptibility to mycobacterial infections, and is treated definitively with HCT. The clinical factors and pathogenesis of IRIS in HCT require further investigation. Methods We conducted a retrospective review of 32 patients with GATA2 deficiency and mycobacterial infections who completed &amp;gt; 6 months of follow-up after HCT. Uniform criteria were used to define cases of IRIS (Image 1). IRIS cases were classified as either early (post-HCT day &amp;lt; 60), intermediate (days 61-120), or late (day &amp;gt; 120). Image 1. Post-Hematopoietic Cell Transplant IRIS Criteria Criteria were adapted to hematopoietic cell transplantation from the AIDS Clinical Trial Group IRIS criteria. Results Clinical characteristics are shown in Image 2. IRIS was identified in 12 (35%) patients (Images 2-3). These patients were more likely to have disseminated infection (P=0.03), an elevated pre-HCT ferritin (P=0.03), and a lower day 30 post-HCT CD4 count (P=0.04). Median time to IRIS was 100 days (Image 4). Pre-transplant duration of mycobacterial therapy correlated with time to IRIS (Pearson’s r=0.58, P=0.05). Conditioning regimens using total body irradiation with or without cyclophosphamide were associated with longer time to IRIS (hazard ratio=0.04, P=0.02). A rise in CD3 chimerism was seen during early cases of IRIS, but not intermediate to late (P=0.002). IRIS emerged during tapering of systemic immunosuppressive therapy in 33% of cases. IRIS was managed conservatively (50%), by intensification of anti-mycobacterial treatment (8%) or by intensification of immunosuppression (42%). Conclusion Development of mycobacterial IRIS after HCT for GATA2 deficiency was associated with disseminated infection, a high pre-transplant ferritin, and low day 30 CD4 count. These findings suggest that antigen burden, a hyperinflammatory state leading into transplantation, and CD4 nadir after HCT have a role in its pathogenesis. Early cases of IRIS may emerge during lymphoid engraftment and CD4 recovery, whereas late cases may emerge with decreases in immunosuppressive therapy and more intensive conditioning regimens. Clinical outcomes were similar to non-IRIS patients. Disclosures All Authors: No reported disclosures

Development of MDS in Pediatric Patients with GATA2 Deficiency: Increased Histone Trimethylation and Deregulated Apoptosis as Potential Drivers of Transformation

GATA2 deficiency is a heterogeneous, multisystem disorder associated with a high risk of developing myelodysplastic syndrome (MDS) and the progression to acute myeloid leukemia. The mechanisms underlying malignant transformation in GATA2 deficiency remain poorly understood, necessitating predictive markers to assess an individual’s risk of progression and guide therapeutic decisions. In this study, we performed a systematic analysis of bone marrow biopsies from 57 pediatric MDS patients. Focusing on hematopoiesis and the hematopoietic niche, including its microenvironment, we used multiplex immunofluorescence combined with multispectral imaging, gene expression profiling, and multiplex RNA in situ hybridization. Patients with a GATA2 deficiency exhibited a dysregulated GATA2 transcriptional network. Disease progression (GATA2-EB, n = 6) was associated with increased GATA2 mRNA levels, restored expression of the GATA2 target EZH2, and increased H3K27me3. GATA2-EB was further characterized by the high expression of the anti-apoptotic protein BCL2, a feature absent in children with a GATA2 deficiency and refractory cytopenia of childhood (GATA2-RCC, n = 24) or other pediatric MDS subgroups (RCC, n = 17; MDS-EB, n = 10). The multispectral imaging analysis of additional BCL2 family members revealed significantly elevated Mediators of Apoptosis Combinatorial (MAC) scores in GATA2-EB patients. Taken together, our findings highlight the potential drivers of disease progression in GATA2 deficiency, particularly increased histone trimethylation and dysregulated apoptosis. Furthermore, upregulated BCL2 and EZH2 and increased MAC scores provide a strong rationale for the use of venetoclax and azacitidine in therapeutic regimens for GATA2-EB.