Acquired and germline predisposition to bone marrow failure: Diagnostic features and clinical implications

A unified metric of human immune health

Immunological health has been challenging to characterize but could be defined as the absence of immune pathology. While shared features of some immune diseases and the concept of immunologic resilience based on age-independent adaptation to antigenic stimulation have been developed, general metrics of immune health and its utility for assessing clinically healthy individuals remain ill defined. Here we integrated transcriptomics, serum protein, peripheral immune cell frequency and clinical data from 228 patients with 22 monogenic conditions impacting key immunological pathways together with 42 age- and sex-matched healthy controls. Despite the high penetrance of monogenic lesions, differences between individuals in diverse immune parameters tended to dominate over those attributable to disease conditions or medication use. Unsupervised or supervised machine learning independently identified a score that distinguished healthy participants from patients with monogenic diseases, thus suggesting a quantitative immune health metric (IHM). In ten independent datasets, the IHM discriminated healthy from polygenic autoimmune and inflammatory disease states, marked aging in clinically healthy individuals, tracked disease activities and treatment responses in both immunological and nonimmunological diseases, and predicted age-dependent antibody responses to immunizations with different vaccines. This discriminatory power goes beyond that of the classical inflammatory biomarkers C-reactive protein and interleukin-6. Thus, deviations from health in diverse conditions, including aging, have shared systemic immune consequences, and we provide a web platform for calculating the IHM for other datasets, which could empower precision medicine.

Impaired Mitochondrial Function and Marrow Failure in Patients Carrying a Variant of the SRSF4 Gene

Serine/arginine-rich splicing factors (SRSFs) are a family of proteins involved in RNA metabolism, including pre-mRNA constitutive and alternative splicing. The role of SRSF proteins in regulating mitochondrial activity has already been shown for SRSF6, but SRSF4 altered expression has never been reported as a cause of bone marrow failure. An 8-year-old patient admitted to the hematology unit because of leukopenia, lymphopenia, and neutropenia showed a missense variant of unknown significance of the SRSF4 gene (p.R235W) found via whole genome sequencing analysis and inherited from the mother who suffered from mild leuko-neutropenia. Both patients showed lower SRSF4 protein expression and altered mitochondrial function and energetic metabolism in primary lymphocytes and Epstein-Barr-virus (EBV)-immortalized lymphoblasts compared to healthy donor (HD) cells, which appeared associated with low mTOR phosphorylation and an imbalance in the proteins regulating mitochondrial biogenesis (i.e., CLUH) and dynamics (i.e., DRP1 and OPA1). Transfection with the wtSRSF4 gene restored mitochondrial function. In conclusion, this study shows that the described variant of the SRSF4 gene is pathogenetic and causes reduced SRSF4 protein expression, which leads to mitochondrial dysfunction. Since mitochondrial function is crucial for hematopoietic stem cell maintenance and some genetic bone marrow failure syndromes display mitochondrial defects, the SRSF4 mutation could have substantially contributed to the clinical phenotype of our patient.

The psychological impact of genetic testing in childhood cancer: A systematic review

OBJECTIVE

Cancer predisposition syndromes are being more frequently recognized in the etiology of pediatric oncology and genetic-related technologies are evolving rapidly, leading to an increasing availability of genetic testing for families. This systematic review assessed the psychological impact of genetic testing on children and parents in the context of childhood cancer.

METHODS

Searches were performed using three databases (Web of Science, Pubmed and Embase) to identify relevant empirical studies. Following Cochrane guidelines, we screened 3838 articles and identified 18 eligible studies, representing the perspectives of children and/or parents.

RESULTS

The included studies described the impact of genetic testing in different contexts (e.g. predictive testing and diagnostic testing) and in different subgroups, (e.g. carriers and non-carriers). Overall, the studies did not identify clinically-relevant long-term increases in negative emotions (depression, anxiety, distress, uncertainty, guilt) as a result of genetic testing. Negative emotions were typically time-limited and generally occurred in families with particular characteristics (e.g. those with a history of multiple cancer diagnoses, families receiving an unfavorable result for one child and a favorable result in siblings, and those with pre-existing mental health difficulties). Positive emotions (hopefulness, relief and peace of mind) were also reported. Knowing their genetic risk status appeared to help to foster empowerment among families, regardless of the result and any associated emotions.

CONCLUSIONS

Genetic testing in pediatric oncology does not appear to cause significant additional harm and can lead to positive outcomes. Clinicians need to be especially attentive when counseling families at increased risk of distress.

A novel GATA2 distal enhancer mutation results in MonoMAC syndrome in 2 second cousins

Mutations in the transcription factor GATA2 can cause MonoMAC syndrome, a GATA2 deficiency disease characterized by several findings, including disseminated nontuberculous mycobacterial infections, severe deficiencies of monocytes, natural killer cells, and B lymphocytes, and myelodysplastic syndrome. GATA2 mutations are found in ∼90% of patients with a GATA2 deficiency phenotype and are largely missense mutations in the conserved second zinc-finger domain. Mutations in an intron 5 regulatory enhancer element are also well described in GATA2 deficiency. Here, we present a multigeneration kindred with the clinical features of GATA2 deficiency but lacking an apparent GATA2 mutation. Whole genome sequencing revealed a unique adenine-to-thymine variant in the GATA2 -110 enhancer 116,855 bp upstream of the GATA2 ATG start site. The mutation creates a new E-box consensus in position with an existing GATA-box to generate a new hematopoietic regulatory composite element. The mutation segregates with the disease in several generations of the family. Cell type-specific allelic imbalance of GATA2 expression was observed in the bone marrow of a patient with higher expression from the mutant-linked allele. Allele-specific overexpression of GATA2 was observed in CRISPR/Cas9-modified HL-60 cells and in luciferase assays with the enhancer mutation. This study demonstrates overexpression of GATA2 resulting from a single nucleotide change in an upstream enhancer element in patients with MonoMAC syndrome. Patients in this study were enrolled in the National Institute of Allergy and Infectious Diseases clinical trial and the National Cancer Institute clinical trial (both trials were registered at www.clinicaltrials.gov as #NCT01905826 and #NCT01861106, respectively).

Hematopoietic stem cell transplantation of aplastic anemia by relative with mutations and normal telomere length: A case report

BACKGROUND

Immunosuppressive therapy and matched sibling donor hematopoietic stem cell transplantation (MSD-HSCT) are the preferred treatments for aplastic anemia (AA).

CASE SUMMARY

In this report, we describe a 43-year-old male patient with severe AA who carried BRIP1 (also known as FANCJ), TINF2, and TCIRG1 mutations. Screening of the family pedigree revealed the same TINF2 mutation in his mother and older brother, with his older brother also carrying the BRIP1 variant and demonstrating normal telomere length and hematopoietic function. The patient was successfully treated with oral cyclosporine A, eltrombopag, and acetylcysteine, achieving remission 4 years after receiving MSD-HSCT from his older brother.

CONCLUSION

This case provides a valuable clinical reference for individuals with suspected pathogenic gene mutations, normal telomere length, and hematopoietic function, highlighting them as potential donors for patients with AA.

The Times, They Are A-Changing: The Impact of Next-Generation Sequencing on Diagnosis, Classification, and Prognostication of Myeloid Malignancies With Focus on Myelodysplastic Syndrome, AML, and Germline Predisposition

Myeloid malignancies are a manifestation of clonal expansion of hematopoietic cells driven by somatic genetic alterations that may arise in a potential background of deleterious germline variants. As next-generation sequencing technology has become more accessible, real-world experience has allowed integration of molecular genomic data with morphology, immunophenotype, and conventional cytogenetics to refine our understanding of myeloid malignancies. This has prompted revisions in the classification and the prognostication schema of myeloid malignancies and germline predisposition to hematologic malignancies. This review provides an overview of significant changes in the recently published classifications of AML and myelodysplastic syndrome, emerging prognostic scoring, and the role of germline deleterious variants in predisposing to MDS and AML.

A New Artificial Intelligence Approach Using Extreme Learning Machine as the Potentially Effective Model to Predict and Analyze the Diagnosis of Anemia

The procedure to diagnose anemia is time-consuming and resource-intensive due to the existence of a multitude of symptoms that can be felt physically or seen visually. Anemia also has several forms, which can be distinguished based on several characteristics. It is possible to diagnose anemia through a quick, affordable, and easily accessible laboratory test known as the complete blood count (CBC), but the method cannot directly identify different kinds of anemia. Therefore, further tests are required to establish a gold standard for the type of anemia in a patient. These tests are uncommon in settings that offer healthcare on a smaller scale because they require expensive equipment. Moreover, it is also difficult to discern between beta thalassemia trait (BTT), iron deficiency anemia (IDA), hemoglobin E (HbE), and combination anemias despite the presence of multiple red blood cell (RBC) formulas and indices with differing optimal cutoff values. This is due to the existence of several varieties of anemia in individuals, making it difficult to distinguish between BTT, IDA, HbE, and combinations. Therefore, a more precise and automated prediction model is proposed to distinguish these four types to accelerate the identification process for doctors. Historical data were retrieved from the Laboratory of the Department of Clinical Pathology and Laboratory Medicine, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia for this purpose. Furthermore, the model was developed using the algorithm for the extreme learning machine (ELM). This was followed by the measurement of the performance using the confusion matrix and 190 data representing the four classes, and the results showed 99.21% accuracy, 98.44% sensitivity, 99.30% precision, and an F1 score of 98.84%.

Inherited bone marrow failure syndromes: a review of current practices and potential future research directions

PURPOSE OF REVIEW

Recent advances in diagnosis and treatment of inherited bone marrow failure syndromes (IBMFS) have significantly improved disease understanding and patient outcomes. Still, IBMFS present clinical challenges that require further progress. This review aims to provide an overview of the current state of diagnosis and treatment modalities of the major IBMFS seen in paediatrics and present areas of prioritization for future research.

RECENT FINDINGS

Haematopoietic cell transplantation (HCT) for IBMFS has greatly improved in recent years, shifting the research and clinical focus towards cancer predispositions and adverse effects of treatment. Each year, additional novel genes and pathogenic variants are described, and genotype-phenotype mapping becomes more sophisticated. Moreover, novel therapeutics exploring disease-specific mechanisms show promise to complement HCT and treat patients who cannot undergo current treatment options.

SUMMARY

Research on IBMFS should have short-term and long-term goals. Immediate challenges include solidifying diagnostic and treatment guidelines, cancer detection and treatment, and continued optimization of HCT. Long-term goals should emphasize genotype-phenotype mapping, genetic screening tools and gene-targeted therapy.

Whole-exome sequencing identifies FANC heterozygous germline mutation as an adverse factor for immunosuppressive therapy in Chinese aplastic anemia patients aged 40 or younger: a single-center retrospective study

Acquired aplastic anemia (AA) is a bone marrow failure disorder characterized by pancytopenia, and immunosuppressive therapy (IST) is the optional first-line management. Several studies identified the influencing factors on IST response; however, there are still a considerable number of patients suffering from poor prognoses. In this study, we enrolled 61 AA patients aged ≤ 40 years old, and whole-exome sequencing (WES) found unexpected high FANC heterozygous germline mutations (28/61, 45.9%). Patients with FANC mutations have a significantly lower absolute reticulocyte count and CD34⁺ % in the bone marrow and also lower 3-, 6-, and 9-month IST response than that without mutation, which were 0% vs. 25% (P = 0.017), 26.3% vs. 42.1% (P = 0.495), and 29.4% vs. 72.2% (P = 0.011), especially in anti-thymocyte globulin combined with the cyclosporin A (ATG + CsA) group, which were 0% vs.33.4% (P = 0.143), 25% vs.83.3% (P = 0.103), and 25% vs. 100% (P = 0.003), respectively. The event-free survival in the FANC^wt group was also better than that in the FANC^mut group (P = 0.016) and also showed in patients who received ATG + CsA treatment (P = 0.045). In addition, all the adverse effects of FANC germline mutation were not significant in stem cell-transplanted group. Our result indicated that the WES-based detection of FANC heterozygous germline mutations may have a great meaning in predicting IST response of acquired AA. This study was registered at chictr.org.cn (# ChiCTR2100054992).

[Sternal bone marrow cell morphology evaluation utility for diagnostic categorization in patients with acquired hypocellular bone marrow failure syndromes]

Objective: Diagnostic value assessment of sternal bone marrow cell morphology in patients with acquired hypocellular bone marrow failure syndromes (BMFS) characterized by normal cytogenetics. Methods: A total of 194 eligible patients with an acquired hypocellular BMFS pre-sternum diagnosis in Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Science & Peking Union Medical College from June 2014 to January 2019 were reviewed. Sternal bone marrow evaluation was performed, and a post-sternum diagnosis was made. Clinical characteristics and overall survival (OS) were then compared among patients with different post-sternum diagnosis. Binary logistic regression was used to develop a predictive scoring system. Results: In 152 patients with pre-sternum AA diagnosis, 29 patients with a pre-sternum idiopathic cytopenia of undetermined significance (ICUS) diagnosis, and 13 patients with a pre-sternum clonal cytopenia of undetermined significance (CCUS) diagnosis, sternal bone marrow evaluation resulted in a change of diagnosis to hypocellular myelodysplastic syndrome (hypo-MDS) in 42.8% (65/152) , 24.1% (7/29) , and 30.8% (4/13) , respectively. Patients with a post-sternum hypo-MDS diagnosis showed a significant difference in OS compared with patients with a post-sternum AA diagnosis (P=0.005) . Patients with ICUS/CCUS showed no difference in OS compared with AA and hypo-MDS (P=0.095 and P=0.480, respectively) . A 4-item predictive scoring system to identify hypocellular BMFS patients that need sternal bone marrow evaluation was developed, including age > 60 years old (OR=6.647, 95% CI 1.954-22.611, P=0.002, 2 points) , neutrophil alkaline phosphatase score ≤ 160 (OR=2.654, 95% CI 1.214-5.804, P=0.014, 1 point) , abnormal erythroid markers evaluated by flow cytometry on iliac bone marrow (OR=6.200, 95% CI 1.165-32.988, P=0.032, 2 points) , and DAT (DNMT3A, ASXL1, TET2) genes mutation (OR=4.809, 95% CI 1.587-14.572, P=0.005, 1 point) . The Akaike information criterin (AIC) was 186.1. Conclusion: Patients with a pre-sternum acquired hypocellular BMFS diagnosis characterized by normal cytogenetics may not reach accurate diagnostic categorization without sternal bone marrow cell morphology evaluation, which could be considered a diagnostic tool for this patient population. A predictive scoring system was developed, and when the total score is ≥ 2 points, sternal bone marrow evaluation should be performed for accurate diagnostic categorization that is critical to optimal patient care.

Targeting CD38 in Neoplasms and Non-Cancer Diseases

Simple Summary

CD38 remains an interesting target for anticancer therapy. Its relatively high abundance in neoplasms and crucial impact on NAD+/cADPR metabolism and the activity of T cells allows for changing the immune response in autoimmune diseases, neoplasms, and finally the induction of cell death. Antibody-dependent cell cytotoxicity is responsible for cell death induced by targeting the tumor with anti-CD38 antibodies, such as daratumumab. A wide range of laboratory experiments and clinical trials show an especially promising role of anti-CD38 therapy against multiple myeloma, NK cell lymphomas, and CD19- B-cell malignancies. More studies are required to include more diseases in the therapeutic protocols involving the modulation of CD38 activity.

Abstract

CD38 is a myeloid antigen present both on the cell membrane and in the intracellular compartment of the cell. Its occurrence is often enhanced in cancer cells, thus making it a potential target in anticancer therapy. Daratumumab and isatuximab already received FDA approval, and novel agents such as MOR202, TAK079 and TNB-738 undergo clinical trials. Also, novel therapeutics such as SAR442085 aim to outrank the older antibodies against CD38. Multiple myeloma and immunoglobulin light-chain amyloidosis may be effectively treated with anti-CD38 immunotherapy. Its role in other hematological malignancies is also important concerning both diagnostic process and potential treatment in the future. Aside from the hematological malignancies, CD38 remains a potential target in gastrointestinal, neurological and pulmonary system disorders. Due to the strong interaction of CD38 with TCR and CD16 on T cells, it may also serve as the biomarker in transplant rejection in renal transplant patients. Besides, CD38 finds its role outside oncology in systemic lupus erythematosus and collagen-induced arthritis. CD38 plays an important role in viral infections, including AIDS and COVID-19. Most of the undergoing clinical trials focus on the use of anti-CD38 antibodies in the therapy of multiple myeloma, CD19- B-cell malignancies, and NK cell lymphomas. This review focuses on targeting CD38 in cancer and non-cancerous diseases using antibodies, cell-based therapies and CD38 inhibitors. We also provide a summary of current clinical trials targeting CD38.

Genetics and genomics of bone marrow failure syndrome

Inherited bone marrow failure syndrome (IBMFS) is a group of clinically heterogeneous disorders characterized by significant hematological cytopenias of one or more hematopoietic cell lineages and is associated with an increased risk of cancer. The genetic etiology of IBMFS includes germline mutations impacting several key biological processes, such as DNA repair, telomere biology, and ribosome biogenesis, which may cause four major syndromes: Fanconi anemia, dyskeratosis congenita, Diamond-Blackfan anemia, and Shwachman-Diamond syndrome. Although the clinical features of some patients may be typical of a particular IBMFS, overlapping and atypical clinical manifestations and variable penetrance pose diagnostic challenges. Here, we review the clinical and genetic features of the major forms of IBMFS and discuss their molecular genetic diagnosis. Next-generation sequencing-based gene panel testing or whole exome sequencing will help elucidate the genetic causes and underlying mechanisms of this genetically heterogeneous group of diseases.

A family with cytotoxic T-lymphocyte-associated protein 4 haploinsufficiency presenting with aplastic anaemia

Acquired aplastic anaemia is a rare disease, and occurrence in more than one member of the same family is uncommon. With this case report, we wish to highlight the importance of searching for an underlying genetic cause when this occurs. It may have consequences for future generations in affected families. CTLA4 haploinsufficiency is a heterogeneous disease entity with severe systemic immune dysregulation associated with several autoimmune diseases including aplastic anaemia.

ASXL1 and STAG2 are common mutations in GATA2 deficiency patients with bone marrow disease and myelodysplastic syndrome

Patients with GATA2 deficiencyharbor de novo or inherited germline mutations in the GATA2 transcription factor gene, predisposing them to myeloid malignancies. There is considerable variation in disease progression, even among family members with the same mutation in GATA2. We investigated somatic mutations in 106 patients with GATA2 deficiency to identify acquired mutations that are associated with myeloid malignancies. Myelodysplastic syndrome (MDS) was the most common diagnosis (∼44%), followed by GATA2 bone marrow immunodeficiency disorder (G2BMID; ∼37%). Thirteen percent of the cohort had GATA2 mutations but displayed no disease manifestations. There were no correlations between age or sex with disease progression or survival. Cytogenetic analyses showed a high incidence of abnormalities (∼43%), notably trisomy 8 (∼23%) and monosomy 7 (∼12%), but the changes did not correlate with lower survival. Somatic mutations in ASXL1 and STAG2 were detected in ∼25% of patients, although the mutations were rarely concomitant. Mutations in DNMT3A were found in ∼10% of patients. These somatic mutations were found similarly in G2BMID and MDS, suggesting clonal hematopoiesis in early stages of disease, before the onset of MDS. ASXL1 mutations conferred a lower survival probability and were more prevalent in female patients. STAG2 mutations also conferred a lower survival probability, but did not show a statistically significant sex bias. There was a conspicuous absence of many commonly mutated genes associated with myeloid malignancies, including TET2, IDH1/2, and the splicing factor genes. Notably, somatic mutations in chromatin-related genes and cohesin genes characterized disease progression in GATA2 deficiency.

A new frontier in Fanconi anemia: From DNA repair to ribosome biogenesis

Described by Guido Fanconi almost 100 years ago, Fanconi anemia (FA) is a rare genetic disease characterized by developmental abnormalities, bone marrow failure (BMF) and cancer predisposition. The proteins encoded by FA-mutated genes (FANC proteins) and assembled in the so-called FANC/BRCA pathway have key functions in DNA repair and replication safeguarding, which loss leads to chromosome structural aberrancies. Therefore, since the 1980s, FA has been considered a genomic instability and chromosome fragility syndrome. However, recent findings have demonstrated new and unexpected roles of FANC proteins in nucleolar homeostasis and ribosome biogenesis, the alteration of which impacts cellular proteostasis. Here, we review the different cellular, biochemical and molecular anomalies associated with the loss of function of FANC proteins and discuss how these anomalies contribute to BMF by comparing FA to other major inherited BMF syndromes. Our aim is to determine the extent to which alterations in the DNA damage response in FA contribute to BMF compared to the consequences of the loss of function of the FANC/BRCA pathway on the other roles of the pathway.

Immune Phenomena in Myeloid Neoplasms: An "Egg or Chicken" Question

Immune phenomena are increasingly reported in myeloid neoplasms, and include autoimmune cytopenias/diseases and immunodeficiency, either preceding or complicating acute myeloid leukemia, myelodysplastic syndromes (MDS), chronic myeloproliferative neoplasms, and bone marrow failure (BMF) syndromes. Autoimmunity and immunodeficiency are the two faces of a dysregulated immune tolerance and surveillance and may result, along with contributing environmental and genetic factors, in an increased incidence of both tumors and infections. The latter may fuel both autoimmunity and immune activation, triggering a vicious circle among infections, tumors and autoimmune phenomena. Additionally, alterations of the microbiota and of mesenchymal stem cells (MSCs) pinpoint to the importance of a permissive or hostile microenvironment for tumor growth. Finally, several therapies of myeloid neoplasms are aimed at increasing host immunity against the tumor, but at the price of increased autoimmune phenomena. In this review we will examine the epidemiological association of myeloid neoplasms with autoimmune diseases and immunodeficiencies, and the pivotal role of autoimmunity in the pathogenesis of MDS and BMF syndromes, including the paroxysmal nocturnal hemoglobinuria conundrum. Furthermore, we will briefly examine autoimmune complications following therapy of myeloid neoplasms, as well as the role of MSCs and microbiota in these settings.

Clinical and Pathologic Spectrum of DDX41-Mutated Hematolymphoid Neoplasms

OBJECTIVES

This study seeks to further characterize the clinicopathologic spectrum of DDX41-mutated hematolymphoid malignancies.

METHODS

We identified DDX41 mutations from a cohort of known or suspected hematologic disorders and reviewed the corresponding clinical, genetic, phenotypic, and morphologic findings.

RESULTS

DDX41 mutations were identified in 20 (1.4%) of 1,371 cases, including 8 cases of acute myeloid leukemia (AML), 5 cases of myelodysplastic syndrome (MDS), 2 cases of therapy-related MDS/AML, 1 case of primary myelofibrosis, 1 case of chronic myeloid leukemia, 1 case of clonal cytopenia of uncertain significance (CCUS), 1 case of T-cell large granular lymphocytic leukemia (T-LGL), and 1 case of multiple myeloma. DDX41-mutated neoplasms were morphologically heterogeneous with a median cellularity of 20% (range, 10%-100%). Megakaryocyte dysplasia occurred in 7 (35%) of 20 cases and trilineage dysplasia in 1 (5%). Frequently comutated genes include a second, somatic DDX41 mutation (8/19, 42%) followed by mutations in TET2 (20%), DNMT3A (20%), ASXL1 (20%), and CUX1 (20%). Karyotypes were noncomplex in 17 (89%) of 19.

CONCLUSIONS

This report extends the spectrum of DDX41-mutated disorders to include CCUS, T-LGL, and plasma cell disorders. The morphologic features are heterogeneous and nonspecific, highlighting the importance of DDX41 testing during routine workup of hematolymphoid neoplasms.

Inducible Sbds Deletion Impairs Bone Marrow Niche Capacity to Engraft Donor Bone Marrow After Transplantation

Bone marrow (BM) niche-derived signals are critical for facilitating engraftment after hematopoietic stem cell (HSC) transplantation (HSCT). HSCT is required for restoration of hematopoiesis in patients with inherited bone marrow failure syndromes (iBMFS). Shwachman-Diamond syndrome (SDS) is a rare iBMFS associated with mutations in SBDS. Previous studies have demonstrated that SBDS deficiency in osteolineage niche cells causes bone marrow dysfunction that promotes leukemia development. However, it is unknown whether BM niche defects caused by SBDS deficiency also impair efficient engraftment of healthy donor HSC following HSCT, a hypothesis that could explain morbidity seen after clinical HSCT for patients with SDS. Here, we report a mouse model with inducible Sbds deletion in hematopoietic and osteolineage cells. Primary and secondary BM transplantation (BMT) studies demonstrated that SBDS deficiency within BM niches caused poor donor hematopoietic recovery and specifically poor HSC engraftment after myeloablative BMT. We have additionally identified multiple molecular and cellular defects within niche populations that are driven by SBDS deficiency and that are accentuated or develop specifically following myeloablative conditioning. These abnormalities include altered frequencies of multiple niche cell subsets including mesenchymal lineage cells, macrophages and endothelial cells; disruption of growth factor signaling, chemokine pathway activation, and adhesion molecule expression; and p53 pathway activation, and signals involved in cell cycle arrest. Taken together, this study demonstrates that SBDS deficiency profoundly impacts recipient hematopoietic niche function in the setting of HSCT, suggesting that novel therapeutic strategies targeting host niches could improve clinical HSCT outcomes for patients with SDS.

Hematopoietic stem cell transplantation for classical inherited bone marrow failure syndromes: an update

INTRODUCTION

Inherited bone marrow failure syndromes (IBMFS) feature complex molecular pathophysiology resulting in ineffective hematopoiesis and increased risk of progression to myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Allogenic hematopoietic stem cell transplantation (HSCT) is the only well-established cure for the hematological manifestations of these diseases.

AREAS COVERED

In recent years, analysis of large series from international databases (mainly from the European Bone Marrow Transplantation [EBMT] database) has improved knowledge about HSCT in IBMFS. This review, following a thorough Medline search of the pertinent published studies, reports the most recent data on HSCT in IBMFS.

EXPERT OPINION

Despite the common features, IBMFS are very different in their manifestations and in the occurrence and management of HSCT complications. Thus, a 'disease-specific' HSCT using an optimized conditioning regimen based on the characteristics of the disease is essential for achieving long-term survival. The phenotypical heterogeneity associated with extramedullary abnormalities has to be carefully evaluated before HSCT because transplantation may only correct impaired hematopoiesis. HSCT may be associated with the risk of treatment-related mortality and with significant early and late morbidity. For these reasons, the benefits should be carefully weighed against the risks.

A Patient with Kabuki Syndrome Mutation Presenting with Very Severe Aplastic Anemia

Kabuki syndrome (KS) is a rare congenital disorder commonly complicated by humoral immunodeficiency. Patients with KS present with mutation in the histone-lysine N-methyltransferase 2D (KMT2D) gene. Although various KMT2D mutations are often identified in lymphoma and leukemia, those encountered in aplastic anemia (AA) are limited. Herein, we present the case of a 45-year-old Japanese man who developed severe pancytopenia and hypogammaglobulinemia. He did not present with any evident malformations, intellectual disability, or detectable levels of autoantibodies. However, B-cell development was impaired. Therefore, a diagnosis of very severe AA due to a hypoplastic marrow, which did not respond to granulocyte colony-stimulating factor, was made. The patient received umbilical cord blood transplantation but died from a Pseudomonas infection before neutrophil engraftment. Trio whole-exome sequencing revealed a novel missense heterozygous mutation c.15959G >A (p.R5320H) in exon 50 of the KMT2D gene. Moreover, Sanger sequencing of peripheral blood and bone marrow mononuclear cells and a skin biopsy specimen obtained from this patient identified this heterozygous mutation, suggesting that de novo mutation associated with KS occurred in the early embryonic development. Our case showed a novel association between KS mutation and adult-onset AA.

Genetic screening of children with marrow failure. The role of primary Immunodeficiencies

The differential diagnosis of marrow failure (MF) is crucial in the diagnostic work-up, since genetic forms require specific care. We retrospectively studied all patients with single/multi-lineage MF evaluated in a single-center to identify the type and incidence of underlying molecular defects. The diepoxybutane test was used to screen Fanconi Anemia. Other congenital MFs have been searched using Sanger and/or Next Generation Sequencing analysis, depending on the available tools over the years. Between 2009-2019, 97 patients (aged 0-32 years-median 5) with single-lineage (29%) or multilineage (68%) MF were evaluated. Fifty-three (54%) and 28 (29%) were diagnosed with acquired and congenital MF, respectively. The remaining 16 (17%), with trilinear (n=9) and monolinear (n=7) MF, were found to have an underlying primary immunodeficiency (PID) and showed clinical and biochemical signs of immune-dysregulation in 10/16 (62%) and in 14/16 (87%) of cases, respectively. Clinical signs were also found in 22/53 (41%) and 8/28 (28%) patients with idiopathic and classical cMF, respectively. Eight out of 16 PIDs patients were successfully transplanted, four received immunosuppression, two did not require treatment, and the remaining two died. We show that patients with single/multi-lineage MF may have underlying PIDs in a considerable number of cases and that MF may represent a relevant clinical sign in patients with PIDs, thus widening their clinical phenotype. An accurate immunological work-up should be performed in all patients with MF, and PID-related genes should be considered when screening MF in order to identify disorders that may receive targeted treatments and/or appropriate conditioning regimens before transplant.

The predictive value of PNH clones, 6p CN-LOH, and clonal TCR gene rearrangement for aplastic anemia diagnosis

Acquired aplastic anemia (AA) is a life-threatening bone marrow aplasia caused by the autoimmune destruction of hematopoietic stem and progenitor cells. There are no existing diagnostic tests that definitively establish AA, and diagnosis is currently made via systematic exclusion of various alternative etiologies, including inherited bone marrow failure syndromes (IBMFSs). The exclusion of IBMFSs, which requires syndrome-specific functional and genetic testing, can substantially delay treatment. AA and IBMFSs can have mimicking clinical presentations, and their distinction has significant implications for treatment and family planning, making accurate and prompt diagnosis imperative to optimal patient outcomes. We hypothesized that AA could be distinguished from IBMFSs using 3 laboratory findings specific to the autoimmune pathogenesis of AA: paroxysmal nocturnal hemoglobinuria (PNH) clones, copy-number-neutral loss of heterozygosity in chromosome arm 6p (6p CN-LOH), and clonal T-cell receptor (TCR) γ gene (TRG) rearrangement. To test our hypothesis, we determined the prevalence of PNH, acquired 6p CN-LOH, and clonal TRG rearrangement in 454 consecutive pediatric and adult patients diagnosed with AA, IBMFSs, and other hematologic diseases. Our results indicated that PNH and acquired 6p CN-LOH clones encompassing HLA genes have ∽100% positive predictive value for AA, and they can facilitate diagnosis in approximately one-half of AA patients. In contrast, clonal TRG rearrangement is not specific for AA. Our analysis demonstrates that PNH and 6p CN-LOH clones effectively distinguish AA from IBMFSs, and both measures should be incorporated early in the diagnostic evaluation of suspected AA using the included Bayesian nomogram to inform clinical application.

An update on Fanconi anemia: Clinical, cytogenetic and molecular approaches (Review)

Fanconi anemia is a genetic syndrome clinically characterized by congenital malformations that affect several human systems, leads to progressive bone marrow failure and predisposes an individual to cancer, particularly in the urogenital area as well as the head and neck. It is commonly caused by the biallelic compromise of one of 22 genes involved in the FA/BRCA repair pathway in most cases. The diagnosis is based on clinical suspicion and confirmation using genetic analysis, where the chromosomal breakage test is considered the gold standard. Other diagnostic methods used include western blotting, multiplex ligation-dependent probe amplification and next-generation sequencing. This genetic condition has variable expressiveness, which makes early diagnosis difficult in certain cases. Although early diagnosis does not currently allow for improved cure rates for this condition, it does enable healthcare professionals to perform a specific systematic follow-up and, if indicated, a bone marrow transplantation that improves the mobility and mortality of affected individuals. The present review article is a theoretical revision of the pathophysiology, clinical manifestations and diagnosis methods intended for different specialists and general practitioners to improve the diagnosis of this condition.

Biology and clinical management of hypoplastic MDS: MDS as a bone marrow failure syndrome

Hypoplastic MDS is a subset of MDS characterized by marrow hypocellularity diagnosed in 10-15% of MDS patients. The pathogenesis of this disease shares features of aplastic anemia with activation of the effector T cells against hematopoietic stem and progenitor cells and high-risk MDS with acquisition of somatic mutations that provide survival and growth advantage of these cells in the inflammatory bone marrow microenvironment. Clonal evolution in hypoplastic MDS may be associated with accumulation of DNA damage and progression to AML while clonal hematopoiesis in aplastic anemia is strongly related to immune escape of the hematopoietic cells. Distinction of hypoplastic MDS from other acquired and inherited bone marrow failure syndromes is frequently challenging but it is critical for the appropriate clinical management of the patients. Treatment with immunosuppression is an important component of the clinical approach to patients with hypoplastic MDS while hypomethylating agents and early allogeneic bone marrow transplantation are also considerations in some patients. In this review, we summarize the current literature on the biology of hypoplastic MDS, the differences between this disease and other bone marrow failure syndromes, and the treatment algorithm for patients with this subtype of MDS.

Distinguishing constitutional from acquired bone marrow failure in the hematology clinic

Distinguishing constitutional from immune bone marrow failure (BMF) has important clinical implications. However, the diagnosis is not always straightforward, and immune aplastic anemia, the commonest BMF, is a diagnosis of exclusion. In this review, we discuss a general approach to the evaluation of BMF, focusing on clinical presentations particular to immune and various constitutional disorders as well as the interpretation of bone marrow histology, flow cytometry, and karyotyping. Additionally, we examine the role of specialized testing in both immune and inherited BMF, and discuss genetic testing, both its role in patient evaluation and interpretation of results.

Germline mutations in MDS/AML predisposition disorders

PURPOSE OF REVIEW

Recognition of hereditary hematopoietic malignancies impacts patient management as well as health surveillance strategies for the patient and relatives who share the causative DNA variant. In this review, barriers to the diagnosis and management of patients are outlined.

RECENT FINDINGS

Increasingly, individuals are being recognized as having germline predisposition to hematopoietic malignancies. Clinical testing for these syndromes is difficult for most clinicians given the need to send true germline samples and the lack of standardization in the field with regard to which genes are covered and the types of DNA changes detected. Additional barriers such as insurance coverage, especially for older individuals, and access to clinical experts need to be overcome in the future.

SUMMARY

New research addressing whether use of hematopoietic stem cells with deleterious variants are permissive to transplantation; effective means of delivering genetic counseling and results disclosure to decrease the psychological impact of these diagnoses; and a comprehensive list of all predisposition genes will advance our ability to provide the best treatment possible for our patients and facilitate strategies to maintain excellent health throughout their lifetimes and for members of younger generations.

VIDEO ABSTRACT

Submitted, http://links.lww.com/COH/A22.

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.

Germline predisposition to haematopoietic malignancies

Once thought to be exceedingly rare, the advent of next-generation sequencing has revealed a plethora of germline predisposition disorders that confer risk for haematopoietic malignancies (HMs). These syndromes are now recognized to be much more common than previously thought. The recognition of a germline susceptibility risk allele in an individual impacts the clinical management and health surveillance strategies in the index patient and relatives who share the causative DNA variant. Challenges to accurate clinical testing include a lack of familiarity in many health care providers, the requirement for DNA samples that reasonably approximate the germline state, and a lack of standardization among diagnostic platforms as to which genes are sequenced and their capabilities in detecting the full range of variant types that confer risk. Current knowledge gaps include a comprehensive understanding of all predisposition genes; whether scenarios exist in which an allogeneic stem cell transplant using donor haematopoietic stem cells with deleterious variants is permissive; and effective means of delivering genetic counseling and results disclosure for these conditions. We are hopeful that comprehensive germline genetic testing, universal germline testing for all patients with an HM, universal germline testing for allogeneic haematopoietic stem cell donors, and the development of preventive strategies to delay or even prevent malignancies will be available in the near future. These factors will likely contribute to improved health outcomes for at-risk individuals and their family members.

The Emerging Role of Hematopathologists and Molecular Pathologists in Detection, Monitoring, and Management of Myeloid Neoplasms with Germline Predisposition

PURPOSE OF REVIEW

Awareness, widespread availability, and routine use of sequencing techniques in work-up of myelodysplastic syndromes and acute myeloid leukemia have facilitated increased recognition of these entities arising in a background of germline predisposition disorders (GPD).

RECENT FINDINGS

The latest revisions to the WHO classification of myeloid neoplasms incorporate "myeloid neoplasms with germline predisposition" as a separate entity due to the therapeutic implications of this diagnosis. It has become apparent that some of these entities have unique recognizable morphologic findings that can be challenging to interpret at time. Hence, much needs to be studied, posing a new layer of complexity to hematopathologists and oncologists. A thorough understanding of cytogenetic and molecular findings during disease evolution is essential. Consequently, hematopathologists and molecular pathologists play an increasing role in recognition of bone marrow morphologic features that help in recognition of underlying GPD, monitoring, and prompt identification of progression.

Special issues related to the diagnosis and management of acquired aplastic anemia in countries with restricted resources, a report on behalf of the Eastern Mediterranean blood and marrow transplantation (EMBMT) group and severe aplastic anemia working party of the European Society for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia is a relatively rare but potentially fatal disorder, with a reported higher incidence in developing countries in comparison to the West. There are significant variations in epidemiological as well as etiological factors of bone marrow failure syndromes in the developing countries in comparison to the developed world. Furthermore, the management of bone marrow failure syndromes in resource constraint settings has significant challenges including delayed diagnosis and referral, limited accessibility to healthcare facilities, treatment modalities as well as limitations related to patients who require allogeneic stem cell transplantation. Here we will provide a review of the available evidence related to specific issues of aplastic anemia in the developing countries and we summarize suggested recommendations from the Eastern Mediterranean blood and bone marrow transplantation (EMBMT) group and the severe aplastic anemia working party of the European Society of blood and marrow transplantation (SAAWP of EBMT) related to the diagnosis and therapeutic options in countries with restricted resources.

When Should We Think of Myelodysplasia or Bone Marrow Failure in a Thrombocytopenic Patient? A Practical Approach to Diagnosis

Thrombocytopenia can arise from various conditions, including myelodysplastic syndromes (MDS) and bone marrow failure (BMF) syndromes. Meticulous assessment of the peripheral blood smear, identification of accompanying clinical conditions, and characterization of the clinical course are important for initial assessment of unexplained thrombocytopenia. Increased awareness is required to identify patients with suspected MDS or BMF, who are in need of further investigations by a step-wise approach. Bone marrow cytomorphology, histopathology, and cytogenetics are complemented by myeloid next-generation sequencing (NGS) panels. Such panels are helpful to distinguish reactive cytopenia from clonal conditions. MDS are caused by mutations in the hematopoietic stem/progenitor cells, characterized by cytopenia and dysplasia, and an inherent risk of leukemic progression. Aplastic anemia (AA), the most frequent acquired BMF, is immunologically driven and characterized by an empty bone marrow. Diagnosis remains challenging due to overlaps with other hematological disorders. Congenital BMF, certainly rare in adulthood, can present atypically with thrombocytopenia and can be misdiagnosed. Analyses for chromosome fragility, telomere length, and germline gene sequencing are needed. Interdisciplinary expert teams contribute to diagnosis, prognostication, and choice of therapy for patients with suspected MDS and BMF. With this review we aim to increase the awareness and provide practical approaches for diagnosis of these conditions in suspicious cases presenting with thrombocytopenia.

Inherited predisposition to haematopoietic malignancies: overcoming barriers and exploring opportunities

Inherited predisposition to haematopoietic malignancies, due to deleterious germline variants in a variety of genes, is an important clinical entity with implications for the health and management of patients and their family members. Unfortunately, there remain several common misconceptions in this field that can result in patients going unrecognised and/or having incomplete or improper testing including: the impression that inherited haematological malignancy syndromes are rare, that myeloid and lymphoid malignancy predisposition syndromes are mutually exclusive, and that solid tumour predisposition syndromes are unique and distinct from haematopoietic malignancy predisposition syndromes. In the present review, we challenge these ideas with our insights into germline genetic testing for these conditions with the hope that increased awareness and knowledge will overcome barriers and lead to improved diagnosis and management.

The Role of Bone Marrow Evaluation in Clinical Allergy and Immunology Practice: When and Why

Allergists and immunologists rely on other specialists for higher risk procedures such as biopsies of the lung or gastrointestinal tract. However, we perform and interpret a handful of procedures ourselves. Training programs have historically required competency for prescribing immunoglobulin infusions, patch testing, rhino laryngoscopy, lung function testing, and provocation testing for airway hyperreactivity even though other specialists often perform them. Bone marrow aspirations and biopsies are not included in fellowship training assessments despite a significant number of marrow evaluations being requested by allergists and immunologists. For example, nearly 1 marrow assessment per month has been requested over 2 years for patients in the Allergy Immunology Clinic at Walter Reed National Military Medical Center. Marrow assessments are often required for diagnosis, monitoring, and treatment-related toxicities. Interpretive and procedural competency would benefit the field given the range of diseases in clinical immunology practice that require marrow assessment. We have generated a comprehensive list of the major conditions that might require bone marrow assessments in any Allergy and Immunology practice. We then summarize the specific tests that must be ordered and show how to determine sample quality. Finally, some providers may desire procedural competency and for those individuals we discuss tips for the procedure.

Germline mutations: many roles in leukemogenesis

PURPOSE OF REVIEW

The purpose of this review is to summarize the current understanding of germline mutations as they contribute to leukemia development and progression. We also discuss how these new insights may help improve clinical management of germline mutations associated with leukemia.

RECENT FINDINGS

Germline mutations may represent important initial mutations in the development of leukemia where interaction with somatic mutations provide further hits in leukemic progression. In addition, germline mutations may also contribute to leukemogenesis by impacting bone marrow stem-cell microenvironment and immune cell development and function.

SUMMARY

Leukemia is characterized by the clonal expansion of malignant cells secondary to somatic or germline mutations in a variety of genes. Understanding somatic mutations that drive leukemogenesis has drastically improved our knowledge of leukemia biology and led to novel therapeutic strategies. Advances have also been made in identifying germline mutations that may affect leukemic development and progression. This review will discuss the biological and clinical relationship of germline mutations with clonal hematopoiesis, bone marrow microenvironment, and immunity in the progression of leukemia.

Genetic Predisposition to Myelodysplastic Syndrome in Clinical Practice

Myelodysplastic syndromes (MDSs) are a heterogeneous group of marrow failure disorders that primarily affect older persons but also occur at a lower frequency in children and young adults. There is increasing recognition of an inherited predisposition to MDS as well as other myeloid malignancies for patients of all ages. Germline predisposition to MDS can occur as part of a syndrome or sporadic disease. The timely diagnosis of an underlying genetic predisposition in the setting of MDS is important. This article delineates germline genetic causes of MDS and provides a scaffold for the diagnosis and management of patients in this context.

Monitoring and treatment of MDS in genetically susceptible persons

Genetic susceptibility to myelodysplastic syndrome (MDS) occurs in children with inherited bone marrow failure syndromes, including Fanconi anemia, Shwachman Diamond syndrome, and dyskeratosis congenita. Available evidence (although not perfect) supports annual surveillance of the blood count and bone marrow in affected persons. Optimal treatment of MDS in these persons is most commonly transplantation. Careful consideration must be given to host susceptibility to DNA damage when selecting a transplant strategy, because significant dose reductions and avoidance of radiation are necessary. Transplantation before evolution to acute myeloid leukemia (AML) is optimal, because outcomes of AML are extremely poor. Children and adults can present with germline mutations in GATA2 and RUNX1, both of which are associated with a 30% to 40% chance of evolution to MDS. GATA2 deficiency may be associated with a clinically important degree of immune suppression, which can cause severe infections that can complicate transplant strategies. GATA2 and RUNX1 deficiency is not associated with host susceptibility to DNA damage, and therefore, conventional treatment strategies for MDS and AML can be used. RUNX1 deficiency has a highly variable phenotype, and MDS can occur in childhood and later in adulthood within the same families, making annual surveillance with marrow examination burdensome; however, such strategies should be discussed with affected persons, allowing an informed choice.

Genetic predisposition to MDS: diagnosis and management

Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders characterized by clonal hematopoiesis with a propensity to evolve into acute myeloid leukemia. MDS presenting in children and young adults is associated with features clinically and biologically distinct from MDS arising in older adults. MDS presenting in children and young adults is associated with a higher likelihood of an underlying genetic predisposition; however, genetic predisposition is increasingly recognized in a subset of older adults. The diagnosis of a genetic predisposition to MDS informs clinical care and treatment selection. Early diagnosis allows a tailored approach to management and surveillance. Genetic testing now offers a powerful diagnostic approach but also poses new challenges and caveats. Clinical expertise in these disorders together with scientific expertise regarding the affected genes is essential for diagnosis. Understanding the basic mechanisms of genetic predisposition to myeloid malignancies may inform surveillance strategies and lead to novel therapies. The cases presented in this article illustrate challenges to the diagnosis of germline genetic predisposition to MDS and how the diagnosis affects clinical management and treatment.

Transcriptional control of blood cell emergence

The haematopoietic system is established during embryonic life through a series of developmental steps that culminates with the generation of haematopoietic stem cells. Characterisation of the transcriptional network that regulates blood cell emergence has led to the identification of transcription factors essential for this process. Among the many factors wired within this complex regulatory network, ETV2, SCL and RUNX1 are the central components. All three factors are absolutely required for blood cell generation, each one controlling a precise step of specification from the mesoderm germ layer to fully functional blood progenitors. Insight into the transcriptional control of blood cell emergence has been used for devising protocols to generate blood cells de novo, either through reprogramming of somatic cells or through forward programming of pluripotent stem cells. Interestingly, the physiological process of blood cell generation and its laboratory-engineered counterpart have very little in common.