Germline ETV6 mutations and predisposition to hematological malignancies

Germline predisposition to myeloid neoplasms: Characteristics and management of high versus variable penetrance disorders

Myeloid neoplasms with germline predisposition have been recognized increasingly over the past decade with numerous newly described disorders. Penetrance, age of onset, phenotypic heterogeneity, and somatic driver events differ widely among these conditions and sometimes even within family members with the same variant, making risk assessment and counseling of these individuals inherently difficult. In this review, we will shed light on high malignant penetrance (e.g., CEBPA, GATA2, SAMD9/SAMD9L, and TP53) versus variable malignant penetrance syndromes (e.g., ANKRD26, DDX41, ETV6, RUNX1, and various bone marrow failure syndromes) and their clinical features, such as variant type and location, course of disease, and prognostic markers. We further discuss the recommended management of these syndromes based on penetrance with an emphasis on somatic aberrations consistent with disease progression/transformation and suggested timing of allogeneic hematopoietic stem cell transplant. This review will thereby provide important data that can help to individualize and improve the management for these patients.

A new genomic framework to categorize pediatric acute myeloid leukemia

Recent studies on pediatric acute myeloid leukemia (pAML) have revealed pediatric-specific driver alterations, many of which are underrepresented in the current classification schemas. To comprehensively define the genomic landscape of pAML, we systematically categorized 887 pAML into 23 mutually distinct molecular categories, including new major entities such as UBTF or BCL11B, covering 91.4% of the cohort. These molecular categories were associated with unique expression profiles and mutational patterns. For instance, molecular categories characterized by specific HOXA or HOXB expression signatures showed distinct mutation patterns of RAS pathway genes, FLT3 or WT1, suggesting shared biological mechanisms. We show that molecular categories were strongly associated with clinical outcomes using two independent cohorts, leading to the establishment of a new prognostic framework for pAML based on these updated molecular categories and minimal residual disease. Together, this comprehensive diagnostic and prognostic framework forms the basis for future classification of pAML and treatment strategies.

Germline Variants and Characteristic Features of Hereditary Hematological Malignancy Syndrome

Due to the proliferation of genetic testing, pathogenic germline variants predisposing to hereditary hematological malignancy syndrome (HHMS) have been identified in an increasing number of genes. Consequently, the field of HHMS is gaining recognition among clinicians and scientists worldwide. Patients with germline genetic abnormalities often have poor outcomes and are candidates for allogeneic hematopoietic stem cell transplantation (HSCT). However, HSCT using blood from a related donor should be carefully considered because of the risk that the patient may inherit a pathogenic variant. At present, we now face the challenge of incorporating these advances into clinical practice for patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) and optimizing the management and surveillance of patients and asymptomatic carriers, with the limitation that evidence-based guidelines are often inadequate. The 2016 revision of the WHO classification added a new section on myeloid malignant neoplasms, including MDS and AML with germline predisposition. The main syndromes can be classified into three groups. Those without pre-existing disease or organ dysfunction; DDX41, TP53, CEBPA, those with pre-existing platelet disorders; ANKRD26, ETV6, RUNX1, and those with other organ dysfunctions; SAMD9/SAMD9L, GATA2, and inherited bone marrow failure syndromes. In this review, we will outline the role of the genes involved in HHMS in order to clarify our understanding of HHMS.

Germline Predisposition to Myeloid Neoplasms: Diagnostic Concepts and Classifications

Molecular and sequencing advances have led to substantial breakthroughs in the discovery of new genes and inherited mutations associated with increased risk of developing myeloid malignancies. Many of the same germline mutated genes are also drivers of malignancy in sporadic cancer. Recognition of myeloid malignancy associated with germline mutations is essential for proper therapy, disease surveillance, informing related donor selection for hematopoietic stem cell transplantation, and genetic counseling of the patient and affected family members. Some germline mutations are associated with syndromic features that precede the development of malignancy; however, penetrance may be highly variable leading to masking of the syndromic phenotype and/or inherited etiology.

Germline and somatic drivers in inherited hematologic malignancies

Inherited hematologic malignancies are linked to a heterogenous group of genes, knowledge of which is rapidly expanding using panel-based next-generation sequencing (NGS) or whole-exome/whole-genome sequencing. Importantly, the penetrance for these syndromes is incomplete, and disease development, progression or transformation has critical clinical implications. With the earlier detection of healthy carriers and sequential monitoring of these patients, clonal hematopoiesis and somatic driver variants become significant factors in determining disease transformation/progression and timing of (preemptive) hematopoietic stem cell transplant in these patients. In this review, we shed light on the detection of probable germline predisposition alleles based on diagnostic/prognostic 'somatic' NGS panels. A multi-tier approach including variant allele frequency, bi-allelic inactivation, persistence of a variant upon clinical remission and mutational burden can indicate variants with high pre-test probability. We also discuss the shared underlying biology and frequency of germline and somatic variants affecting the same gene, specifically focusing on variants in DDX41, ETV6, GATA2 and RUNX1. Germline variants in these genes are associated with a (specific) pattern or over-/underrepresentation of somatic molecular or cytogenetic alterations that may help identify the underlying germline syndrome and predict the course of disease in these individuals. This review is based on the current knowledge about somatic drivers in these four syndromes by integrating data from all published patients, thereby providing clinicians with valuable and concise information.

State-of-the-Art Targeted High-Throughput Sequencing for Detecting Inherited Platelet Disorders

Inherited platelet disorders (IPDs) are a heterogeneous group of rare entities caused by molecular divergence in genes relevant for platelet formation and function. A rational diagnostic approach is necessary to counsel and treat patients with IPDs. With the introduction of high-throughput sequencing at the beginning of this millennium, a more accurate diagnosis of IPDs has become available. We discuss advantages and limitations of genetic testing, technical issues, and ethical aspects. Additionally, we provide information on the clinical significance of different classes of variants and how they are correctly reported.

Transcription factor genetics and biology in predisposition to bone marrow failure and hematological malignancy

Transcription factors (TFs) play a critical role as key mediators of a multitude of developmental pathways, with highly regulated and tightly organized networks crucial for determining both the timing and pattern of tissue development. TFs can act as master regulators of both primitive and definitive hematopoiesis, tightly controlling the behavior of hematopoietic stem and progenitor cells (HSPCs). These networks control the functional regulation of HSPCs including self-renewal, proliferation, and differentiation dynamics, which are essential to normal hematopoiesis. Defining the key players and dynamics of these hematopoietic transcriptional networks is essential to understanding both normal hematopoiesis and how genetic aberrations in TFs and their networks can predispose to hematopoietic disease including bone marrow failure (BMF) and hematological malignancy (HM). Despite their multifaceted and complex involvement in hematological development, advances in genetic screening along with elegant multi-omics and model system studies are shedding light on how hematopoietic TFs interact and network to achieve normal cell fates and their role in disease etiology. This review focuses on TFs which predispose to BMF and HM, identifies potential novel candidate predisposing TF genes, and examines putative biological mechanisms leading to these phenotypes. A better understanding of the genetics and molecular biology of hematopoietic TFs, as well as identifying novel genes and genetic variants predisposing to BMF and HM, will accelerate the development of preventative strategies, improve clinical management and counseling, and help define targeted treatments for these diseases.

Rescuing biologically relevant consensus regions across replicated samples

BACKGROUND

Protein-DNA binding sites of ChIP-seq experiments are identified where the binding affinity is significant based on a given threshold. The choice of the threshold is a trade-off between conservative region identification and discarding weak, but true binding sites.

RESULTS

We rescue weak binding sites using MSPC, which efficiently exploits replicates to lower the threshold required to identify a site while keeping a low false-positive rate, and we compare it to IDR, a widely used post-processing method for identifying highly reproducible peaks across replicates. We observe several master transcription regulators (e.g., SP1 and GATA3) and HDAC2-GATA1 regulatory networks on rescued regions in K562 cell line.

CONCLUSIONS

We argue the biological relevance of weak binding sites and the information they add when rescued by MSPC. An implementation of the proposed extended MSPC methodology and the scripts to reproduce the performed analysis are freely available at https://genometric.github.io/MSPC/ ; MSPC is distributed as a command-line application and an R package available from Bioconductor ( https://doi.org/doi:10.18129/B9.bioc.rmspc ).

Clinical considerations at the intersection of hematopoietic cell transplantation and hereditary hematopoietic malignancy

In recent years, advances in genetics and the integration of clinical-grade next-generation sequencing (NGS) assays into patient care have facilitated broader recognition of hereditary hematopoietic malignancy (HHM) among clinicians, in addition to the identification and characterization of novel HHM syndromes. Studies on genetic risk distribution within affected families and unique considerations of HHM biology represent exciting areas of translational research. More recently, data are now emerging pertaining to unique aspects of clinical management of malignancies arising in the context of pathogenic germline mutations, with particular emphasis on chemotherapy responsiveness. In this article, we explore considerations surrounding allogeneic transplantation in the context of HHMs. We review pre- and post-transplant patient implications, including genetic testing donor selection and donor-derived malignancies. Additionally, we consider the limited data that exist regarding the use of transplantation in HHMs and safeguards that might be pursued to mitigate transplant-related toxicities.

Germline Predisposition to Myelodysplastic Syndromes

ABSTRACT

While germline predisposition to myelodysplastic syndromes is well-established, knowledge has advanced rapidly resulting in more cases of inherited hematologic malignancies being identified. Understanding the biological features and main clinical manifestations of hereditary hematologic malignancies is essential to recognizing and referring patients with myelodysplastic syndrome, who may underlie inherited predisposition, for appropriate genetic evaluation. Importance lies in individualized genetic counseling along with informed treatment decisions, especially with regard to hematopoietic stem cell transplant-related donor selection. Future studies will improve comprehension of these disorders, enabling better management of affected patients and their families.

Hereditary platelet disorders associated with germ line variants in RUNX1, ETV6, and ANKRD26

Hereditary platelet disorders (HPDs) are a group of blood disorders with variable severity and clinical impact. Although phenotypically there is much overlap, known genetic causes are many, prompting the curation of multigene panels for clinical use, which are being deployed in increasingly large-scale populations to uncover missing heritability more efficiently. For some of these disorders, in particular RUNX1, ETV6, and ANKRD26, pathogenic germ line variants in these genes also come with a risk of developing hematological malignancy (HM). Although they may initially present as similarly mild-moderate thrombocytopenia, each of these 3 disorders have distinct penetrance of HM and a different range of somatic alterations associated with malignancy development. As our ability to diagnose HPDs has improved, we are now faced with the challenges of integrating these advances into routine clinical practice for patients and how to optimize management and surveillance of patients and carriers who have not developed malignancy. The volume of genetic information now being generated has created new challenges in how to accurately assess and report identified variants. The answers to all these questions involve international initiatives on rare diseases to better understand the biology of these disorders and design appropriate models and therapies for preclinical testing and clinical trials. Partnered with this are continued technological developments, including the rapid sharing of genetic variant information and automated integration with variant classification relevant data, such as high-throughput functional data. Collective progress in this area will drive timely diagnosis and, in time, leukemia preventive therapeutic interventions.

The Clinical Spectrum, Diagnosis, and Management of GATA2 Deficiency

Hereditary myeloid malignancy syndromes (HMMSs) are rare but are becoming increasingly significant in clinical practice. One of the most well-known syndromes within this group is GATA2 deficiency. The GATA2 gene encodes a zinc finger transcription factor essential for normal hematopoiesis. Insufficient expression and function of this gene as a result of germinal mutations underlie distinct clinical presentations, including childhood myelodysplastic syndrome and acute myeloid leukemia, in which the acquisition of additional molecular somatic abnormalities can lead to variable outcomes. The only curative treatment for this syndrome is allogeneic hematopoietic stem cell transplantation, which should be performed before irreversible organ damage happens. In this review, we will examine the structural characteristics of the GATA2 gene, its physiological and pathological functions, how GATA2 genetic mutations contribute to myeloid neoplasms, and other potential clinical manifestations. Finally, we will provide an overview of current therapeutic options, including recent transplantation strategies.

ETV6 dependency in Ewing sarcoma by antagonism of EWS-FLI1-mediated enhancer activation

The EWS-FLI1 fusion oncoprotein deregulates transcription to initiate the paediatric cancer Ewing sarcoma. Here we used a domain-focused CRISPR screen to implicate the transcriptional repressor ETV6 as a unique dependency in this tumour. Using biochemical assays and epigenomics, we show that ETV6 competes with EWS-FLI1 for binding to select DNA elements enriched for short GGAA repeat sequences. Upon inactivating ETV6, EWS-FLI1 overtakes and hyper-activates these cis-elements to promote mesenchymal differentiation, with SOX11 being a key downstream target. We show that squelching of ETV6 with a dominant-interfering peptide phenocopies these effects and suppresses Ewing sarcoma growth in vivo. These findings reveal targeting of ETV6 as a strategy for neutralizing the EWS-FLI1 oncoprotein by reprogramming of genomic occupancy.

Myeloid neoplasm with ETV6::ACSl6 fusion: landscape of molecular and clinical features

OBJECTIVES

Since the publication of the third edition, the WHO classification of tumors of hematopoietic and lymphoid disorders has introduced the disease entity of 'myeloid/lymphoid neoplasms with eosinophilia and PDGFRB rearrangement', in which the most common chromosomal abnormality is t(5;12) (q32;p13.2), and this abnormality generates the ETV6::PDGFRB fusion gene. However, there have been patients with hematologic features and chromosomal abnormalities that are extremely similar to those carrying ETV6::PDGFRB fusion. These rare disorders harbor ETV6::ACSL6 fusion, and only sporadic cases have been reported at present.

METHODS

We report a patient with chronic eosinophilic leukemia (CEL) carrying chromosome translocation t(5;12)(q32;p13.2), and we present the clinical features. In addition, we conducted a literature review to collect all reported cases and summarized the genetic and clinical profiling as well as the treatments and outcomes.

RESULT

In addition to our patient, a total of 19 cases have been previously reported, including 6 variants of ETV6::ACSL6 and 3 reciprocals. We identified a novel variant of the ETV6::ACSL6 transcript in our patient, and the breakpoint was flanked by exon 2 of ETV6 and exon 2 of ACSL6. The cellular morphology features consisted of myeloproliferative neoplasm (MPN); myelodysplastic/myeloproliferative neoplasm (MDS/MPN), specifically CEL; and acute myelocytic leukemia (AML). The treatments and outcomes varied greatly depending on the type of disease, although tyrosine kinase inhibitors (TKIs) were not effective.

CONCLUSION

In contrast to neoplasms with ETV6::PDGFRB fusion, myeloid neoplasms with ETV6::ACSL6 fusion have unique characteristics.

The genetics of myelodysplastic syndromes and the opportunities for tailored treatments

Genomic instability, microenvironmental aberrations, and somatic mutations contribute to the phenotype of myelodysplastic syndrome and the risk for transformation to AML. Genes involved in RNA splicing, DNA methylation, histone modification, the cohesin complex, transcription, DNA damage response pathway, signal transduction and other pathways constitute recurrent mutational targets in MDS. RNA-splicing and DNA methylation mutations seem to occur early and are reported as driver mutations in over 50% of MDS patients. The improved understanding of the molecular landscape of MDS has led to better disease and risk classification, leading to novel therapeutic opportunities. Based on these findings, novel agents are currently under preclinical and clinical development and expected to improve the clinical outcome of patients with MDS in the upcoming years. This review provides a comprehensive update of the normal gene function as well as the impact of mutations in the pathogenesis, deregulation, diagnosis, and prognosis of MDS, focuses on the most recent advances of the genetic basis of myelodysplastic syndromes and their clinical relevance, and the latest targeted therapeutic approaches including investigational and approved agents for MDS.

Genetic Disorders with Predisposition to Paediatric Haematopoietic Malignancies—A Review

The view of paediatric cancer as a genetic disease arises as genetic research develops. Germline mutations in cancer predisposition genes have been identified in about 10% of children. Paediatric cancers are characterized by heterogeneity in the types of genetic alterations that drive tumourigenesis. Interactions between germline and somatic mutations are a key determinant of cancer development. In 40% of patients, the family history does not predict the presence of inherited cancer predisposition syndromes and many cases go undetected. Paediatricians should be aware of specific symptoms, which highlight the need of evaluation for cancer syndromes. The quickest possible identification of such syndromes is of key importance, due to the possibility of early detection of neoplasms, followed by presymptomatic genetic testing of relatives, implementation of appropriate clinical procedures (e.g., avoiding radiotherapy), prophylactic surgical resection of organs at risk, or searching for donors of hematopoietic stem cells. Targetable driver mutations and corresponding signalling pathways provide a novel precision medicine strategy.Therefore, there is a need for multi-disciplinary cooperation between a paediatrician, an oncologist, a geneticist, and a psychologist during the surveillance of families with an increased cancer risk. This review aimed to emphasize the role of cancer-predisposition gene diagnostics in the genetic surveillance and medical care in paediatric oncology.

Therapeutic targeting of RBPJ, an upstream regulator of ETV6 gene, abrogates ETV6-NTRK3 fusion gene transformations in glioblastoma

Fusion genes are abnormal genes resulting from chromosomal translocation, insertion, deletion, inversion, etc. ETV6, a rather promiscuous partner forms fusions with several other genes, most commonly, the NTRK3 gene. This fusion leads to the formation of a constitutively activated tyrosine kinase which activates the Ras-Raf-MEK and PI3K/AKT/MAPK pathways, leading the cells through cycles of uncontrolled division and ultimately resulting in cancer. Targeted therapies against this ETV6-NTRK3 fusion protein are much needed. Therefore, to find a targeted approach, a transcription factor RBPJ regulating the ETV6 gene was established and since the ETV6-NTRK3 fusion gene is downstream of the ETV6 promoter/enhancer, this fusion protein is also regulated. The regulation of the ETV6 gene via RBPJ was validated by ChIP analysis in human glioblastoma (GBM) cell lines and patient tissue samples. This study was further followed by the identification of an inhibitor, Furamidine, against transcription factor RBPJ. It was found to be binding with the DNA binding domain of RBPJ with antitumorigenic properties and minimal organ toxicity. Hence, a new target RBPJ, regulating the production of ETV6 and ETV6-NTRK3 fusion protein was found along with a potent RBPJ inhibitor Furamidine.

Next generation sequencing in therapy-related myeloid neoplasms compared to de novo myeloid neoplasms

INTRODUCTION

Therapy-related myeloid neoplasms (t-MN) are frequently categorized according to previous therapy or pattern of cytogenetic abnormalities. Our objective was to evaluate and compare the mutational profile of de novo and t-MN by next generation sequencing.

METHODS

Sixty-four samples from patients with t-MN, previously treated for a solid tumor (mainly breast), or de novo AML, MDS, MDS/MPN were selected for our study. The library was prepared using diagnostic samples and the TruSight Myeloid sequencing panel targeting 54 genes. Samples were sequenced on a MiSeq. The classification system of the Belgian ComPerMed Expert Panel was used for the biological variant classification.

RESULTS

Taking only pathogenic, probably pathogenic variants and variants of unknown significance into account 141 variants in 33 genes were found in 52 of 64 samples (81%; mean number of variants per patient = 2; range = [1-11]; 67 variants in 25 genes in t-MN and 74 variants in 25 genes in de novo MN). Overall, the most frequently detected variants included TET2 (n = 22), TP53 (n = 12), DNMT3A (n = 10) and FLT3, NPM1, RUNX1 (n = 8 each).

CONCLUSION

Our study revealed a high variety of variants both in t-MN and de novo MN patients. There was a higher incidence of FLT3 and TP53 variants in t-MN compared to de novo MN.

Prevalence and natural history of variants in the ANKRD26 gene: a short review and update of reported cases

ANKRD26 is a highly conserved gene located on chromosome 10p12.1 which has shown to play a role in normal megakaryocyte differentiation. ANKRD26-related thrombocytopenia, or thrombocytopenia 2, is an inherited thrombocytopenia with mild bleeding diathesis resulting from point mutations the 5ʹUTR of the ANKRD26 gene. Point mutations in the 5ʹUTR region have been shown to prevent transcription factor-mediated downregulation of ANKRD26 in normal megakaryocyte differentiation. Patients with ANKRD26-related thrombocytopenia have a predisposition to developing hematological malignancies, with acute myeloid leukemia and myelodysplastic syndrome most commonly described in the literature. We review the clinical features and biological mechanisms of ANKRD26-related thrombocytopenia and summarize known cases in the literature.

Pedigree investigation, clinical characteristics, and prognosis analysis of haematological disease patients with germline TET2 mutation

Background

Increasing germline gene mutations have been discovered in haematological malignancies with the development of next-generation sequencing (NGS), which is critical for proper clinical management and long-term follow-up of affected individuals. Tet methylcytosine dioxygenase 2 (TET2) is one of the most common mutations in haematological neoplasms. We aimed to compare the clinical characteristics of patients with germline and somatic TET2 mutations in haematological diseases and to analyse whether germline TET2 mutations have a family aggregation and tumour predisposition.

Methods

Out of 612 patients who underwent NGS of 34 recurrently mutated genes in haematological diseases, 100 haematological patients with TET2 mutations were selected for further study. Somatic mutations were detected by NGS in bone marrow/peripheral blood genomic DNA (gDNA). Germline TET2 mutations were validated in nail/hair gDNA by Sanger sequencing. Digital data were extracted from the haematology department of the West China Hospital of Sichuan University. TET2 mutation results were analysed by referencing online public databases (COSMIC and ClinVar).

Results

One hundred patients were studied, including 33 patients with germline and 67 patients with somatic TET2 mutations. For germline TET2 mutations, the variant allele frequency (VAF) was more stable (50.58% [40.5–55], P < 0.0001), and mutation sites recurrently occurred in three sites, unlike somatic TET2 mutations. Patients with germline TET2 mutations were younger (median age 48, 16–82 years) (P = 0.0058) and mainly suffered from myelodysplastic syndromes (MDS) (n = 13, 39.4%), while patients with somatic TET2 mutations were mainly affected by acute myeloid leukemia (AML) (n = 26, 38.8%) (P = 0.0004). Germline TET2 mutation affected the distribution of cell counts in the peripheral blood and bone marrow (P < 0.05); it was a poor prognostic factor for MDS patients via univariate analysis (HR = 5.3, 95% CI: 0.89–32.2, P = 0.0209) but not in multivariate analysis using the Cox regression model (P = 0.062).

Conclusions

Germline TET2 mutation might have a family aggregation, and TET2 may be a predisposition gene for haematological malignancy under the other gene mutations as the second hit. Germline TET2 mutation may play a role in the proportion of blood and bone marrow cells and, most importantly, may be an adverse factor for MDS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09347-0.

Inherited Susceptibility to Hematopoietic Malignancies in the Era of Precision Oncology

As germline predisposition to hematopoietic malignancies has gained increased recognition and attention in the field of oncology, it is important for clinicians to use a systematic framework for the identification, management, and surveillance of patients with hereditary hematopoietic malignancies (HHMs). In this article, we discuss strategies for identifying individuals who warrant diagnostic evaluation and describe considerations pertaining to molecular testing. Although a paucity of prospective data is available to guide clinical monitoring of individuals harboring pathogenic variants, we provide recommendations for clinical surveillance based on consensus opinion and highlight current advances regarding the risk of progression to overt malignancy in HHM variant carriers. We also discuss the prognosis of HHMs and considerations surrounding the utility of allogeneic stem-cell transplantation in these individuals. We close with an overview of contemporary issues at the intersection of HHMs and precision oncology.

ETV6 Regulates Hemin-Induced Erythroid Differentiation of K562 Cells through Mediating the Raf/MEK/ERK Pathway

As a member of transcription factor E-Twenty Six (ETS) family, ETS variant 6 (ETV6) plays significant role in hematopoiesis and embryonic development. ETV6 dysexpression also involved in the occurrence, development and progression of cancers and leukemia. In current work, we hypothesized that ETV6 plays a role in erythroid differentiation of chronic myeloid leukemia (CML). We found the protein expression level of ETV6 was significantly upregulated during hemin-induced erythroid differentiation of K562 cells. Moreover, overexpression of ETV6 inhibited erythroid differentiation in hemin-induced K562 cells with decreased numbers of benzidine-positive cells and decreased expression levels of erythroid differentiation specific markers glycophorin (GPA), CD71, hemoglobin A (HBA), α-globin, γ-globin and ε-globin. Conversely, ETV6 knockdown promoted erythroid differentiation in hemin-induced K562 cells. Furthermore, ETV6 expression level slightly positively with the proliferation capacity of K562 cells treated with hemin. Mechanistically, ETV6 overexpression inhibited fibrosarcoma/mitogen activated extracellular signal-regulated kinase/extracellular regulated protein kinase (Raf/MEK/ERK) pathway, ETV6 knockdown activated the Raf/MEK/ERK pathway. Collectively, the current work demonstrates that ETV6 plays an inhibitory role in the regulation of K562 cell erythroid differentiation via Raf/MEK/ERK pathway, it would be a potentially therapeutic target for dyserythropoiesis.

Integrating germline variant assessment into routine clinical practice for myelodysplastic syndrome and acute myeloid leukaemia: current strategies and challenges

Over the last decade, the field of hereditary haematological malignancy syndromes (HHMSs) has gained increasing recognition among clinicians and scientists worldwide. Germline mutations now account for almost 10% of adult and paediatric myelodysplasia/acute myeloid leukaemia (MDS/AML). As our ability to diagnose HHMSs has improved, we are now faced with the challenges of integrating these advances into routine clinical practice for patients with MDS/AML and how to optimise management and surveillance of patients and asymptomatic carriers. Discoveries of novel syndromes combined with clinical, genetic and epigenetic profiling of tumour samples, have highlighted unique patterns of disease evolution across HHMSs. Despite these advances, causative lesions are detected in less than half of familial cases and evidence-based guidelines are often lacking, suggesting there is much still to learn. Future research efforts are needed to sustain current momentum within the field, led not only by advancing genetic technology but essential collaboration between clinical and academic communities.

Germline mutations among Polish patients with acute myeloid leukemia

BACKGROUND

A small but important proportion of patients (4-10 %) with AML have germline mutations. They can cause the development of AML at an earlier age, confer a higher risk of relapse or predispose to secondary leukemias, including therapy-related leukemias. The analysis of germline mutations in a patient and his/her family is also critical for the selection of suitable family donors if the patient is a candidate for hematopoietic stem cell transplantation (HSCT).

METHODS

103 unrelated consecutive patients with de novo AML were enrolled in the study. Control group consisted of 103 persons from the general population. We performed NGS sequencing of bone marrow cells and buccal swabs DNA of six genes: CEBPA, DDX41, ETV6, TERT, GATA2, and IDH2 to detect germline pathogenic mutations.

RESULTS

In the investigated group, 49 variants were detected in six genes. 26 of them were somatic and 23 germline. Germline variants were detected in all six tested genes. Eight pathogenic germline mutations were detected in 7 AML patients, in three genes: CEBPA, ETV6, and IDH2. One patient had two pathogenic germinal mutations, one in ETV6 and one in CEBPA gene. We identified one novel pathogenic germline mutation in CEBPA gene. The difference in frequency of all pathogenic germline mutations between the tested (7.77 %) and control groups (0.97 %) was statistically significant (p = 0.046). In the tested group, the median age at AML diagnosis was 11 years lower in patients with pathogenic germline mutations than in patients without them (p = 0.028).

CONCLUSIONS

We showed higher frequency of CEBPA, ETV6, and IDH2 germline mutations in AML patients than in control group, which confirms the role of these mutations in the development of AML. We also showed that the median age at the onset of AML in patients with pathogenic germline mutations is significantly lower than in patients without them.

Application of Next-Generation Sequencing-Based Mutational Profiling in Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Recent efforts to characterize hematologic cancers with genetic and molecular detail have largely relied on mutational profiling via next-generation sequencing (NGS). The application of NGS-guided disease prognostication and clinical decision making requires a basic understanding of sequencing advantages, pitfalls, and areas where clinical care might be enhanced by the knowledge generated. This article identifies avenues within the landscape of adult acute lymphoblastic leukemia (ALL) where mutational data hold the opportunity to enhance understanding of disease biology and patient care.

RECENT FINDINGS

NGS-based assessment of measurable residual disease (MRD) after ALL treatment allows for a sensitive and specific molecular survey that is at least comparable, if not superior, to existing techniques. Mutational assessment by NGS has unraveled complex signaling networks that drive pathogenesis of T-cell ALL. Sequencing of patients with familial clustering of ALL has also identified novel germline mutations whose inheritance predisposes to disease development in successive generations. While NGS-based assessment of hematopoietic malignancies often provides actionable information to clinicians, patients with acute lymphoblastic leukemia are left underserved due to a lack of disease classification and prognostication schema that integrate molecular data. Ongoing research is positioned to enrich the molecular toolbox available to clinicians caring for adult ALL patients and deliver new insights to guide therapeutic selection, monitor clinical response, and detect relapse.

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.

Functional analysis of germline ETV6 W380R mutation causing inherited thrombocytopenia and secondary acute lymphoblastic leukemia or essential thrombocythemia

Germline mutations in ETV6 gene cause inherited thrombocytopenia with leukemia predisposition. Here, we report on functional validation of ETV6 W380R mutation segregating with thrombocytopenia in a family where two family members also suffered from acute lymphoblastic leukemia (ALL) or essential thrombocythemia (ET). In-silico analysis predicted impaired DNA binding due to W380R mutation. Functional analysis showed that this mutation prevents the ETV6 protein from localizing into the cell nucleus and impairs the transcriptional repression activity of ETV6. Based on the germline ETV6 mutation, ET probably started with somatic JAK2 V617F mutation, whereas ALL could be caused by diverse mechanisms: high-hyperdiploidity; somatic deletion of exon 1 IKZF1 gene; or somatic mutations of other genes found by exome sequencing of the ALL sample taken at the diagnosis.

ETV6-related thrombocytopenia associated with a transient decrease in von Willebrand factor

ETV6-related thrombocytopenia is an autosomal dominant thrombocytopenia, characterized by a bleeding tendency and predisposition to hematological malignancies. The similarity in symptoms makes differentiating immune and congenital thrombocytopenia challenging. We report a 5-year-old girl who presented with chronic thrombocytopenia associated with repetitive and long-lasting epistaxis, leading to blood transfusion for severe anemia. Blood tests showed thrombocytopenia (52 × 103/µL) with normal-sized platelets and transiently low von Willebrand factor (VWF) levels (VWF:RCo 13%, VWF:Ag 50%); therefore, von Willebrand disease type 2 was initially suspected. Repetition of the blood tests revealed normal levels of VWF. Exome and Sanger sequencing identified a germline ETV6 heterozygous variant, c.641C > T:p.(P214L). No additional pathogenic variants were found, including VWF, in the gene panel testing of the 53 known target causative genes for thrombocytopenia. High-throughput exome sequencing for chronic thrombocytopenia can be utilized to differentially diagnose ETV6-related thrombocytopenia from chronic/intractable immune thrombocytopenia and to effectively monitor malignancy.

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.

Review of guidelines for the identification and clinical care of patients with genetic predisposition for hematological malignancies

Since WHO has recognized myeloid neoplasms with germline predisposition as a new entity in 2016, it has become increasingly clear that diagnosing familial leukemia has critical implications for both the patient and his/her family, and that interdisciplinary teams of hematologists and clinical geneticists should provide care for this specific patient group. Here, we summarize consensus criteria for the identification and screening of patients with genetic predisposition for hematologic malignancies, as provided by different working groups, e.g. by the Nordic MDS group and the AACR. In addition to typical clinical features, results from targeted deep sequencing may point to a genetic predisposition. We review strategies to distinguish somatic and germline variants and discuss recommendations for genetic analyses aiming to identify the underlying genetic variant that should follow established quality criteria to detect both SNVs and CNVs and to determine the pathogenicity of genetic variants. To enhance the knowledge about hematologic neoplasms with germline predisposition we recommend archiving clinical and genetic data and archiving them in international registries.

Diagnosis and treatment of mixed phenotype (T-myeloid/lymphoid) acute leukemia with novel ETV6-FGFR2 rearrangement

Myeloid/lymphoid neoplasms with eosinophilia are driven by aberrant tyrosine kinases in pluripotent cells and display variable phenotypes. FGFR-driven hematolymphoid neoplasms are targetable by TKI inhibitors such as ponatinib; studies of specific FGFR inhibitors are ongoing.

Heterozygous germ line CSF3R variants as risk alleles for development of hematologic malignancies

Colony-stimulating factor 3 receptor (CSF3R) encodes the receptor for granulocyte colony-stimulating factor (G-CSF), a cytokine vital for granulocyte proliferation and differentiation. Acquired activating heterozygous variants in CSF3R are the main cause of chronic neutrophilic leukemia, a hyperproliferative disorder. In contrast, biallelic germ line hypomorphic variants in CSF3R are a rare cause of severe congenital neutropenia, a hypoproliferative condition. The impact of heterozygous germ line CSF3R variants, however, is unknown. We identified CSF3R as a new germ line hematologic malignancy predisposition gene through analysis of 832 next-generation sequencing tests conducted in 632 patients with hematologic malignancies. Among germ line CSF3R variants, 3 were abnormal in functional testing, indicating their deleterious nature. p.Trp547* was identified in 2 unrelated men with myelodysplastic syndromes diagnosed at 76 and 33 years of age, respectively. p.Trp547* is a loss-of-function nonsense variant in the extracellular domain that results in decreased CSF3R messenger RNA expression and abrogation of CSF3R surface expression and proliferative responses to G-CSF. p.Ala119Thr is a missense variant found in 2 patients with multiple myeloma and acute lymphoblastic leukemia, respectively. This variant is located between the extracellular immunoglobulin-like and cytokine receptor homology domains and results in decreased G-CSF sensitivity. p.Pro784Thr was identified in a 67-year-old man with multiple myeloma. p.Pro784Thr is a missense variant in the cytoplasmic domain that inhibits CSF3R internalization, producing a gain-of-function phenotype and G-CSF hypersensitivity. Our findings identify germ line heterozygous CSF3R variants as risk factors for development of myeloid and lymphoid malignancies.

Unique ethnic features of DDX41 mutations in patients with idiopathic cytopenia of undetermined significance, myelodysplastic syndrome, or acute myeloid leukemia

DDX41 mutations are associated with hematologic malignancies including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but the incidence in idiopathic cytopenia of undetermined significance (ICUS) is unknown. We investigated the incidence, genetic characteristics, and clinical features of DDX41 mutations in Korean patients with ICUS, MDS, or AML. We performed targeted deep sequencing of 61 genes including DDX41 in 457 patients with ICUS (n=75), MDS (n=210), or AML (n=172). The germline DDX41 mutations with causality were identified in 28 (6.1%) patients, of whom 27 (96.4%) had somatic mutations in the other position of DDX41. Germline origins of the DDX41 mutations were confirmed in all of the 11 patients who performed germline-based testing. Of the germline DDX41 mutations, p.V152G (n=10) was most common, followed by p.Y259C (n=8), p.A500fs (n=6), and p.E7* (n=3). Compared with non-mutated patients, DDX41-mutated patients showed male predominance, old age, normal karyotype, low leukocyte count, and hypocellular marrow at diagnosis. Three of the 4 ICUS patients with germline DDX41 mutations progressed to MDS. DDX41 mutations in Korean patients showed a high incidence and distinct mutation patterns, in that p.V152G was a unique germline variant. ICUS harboring germline DDX41 mutations may be regarded as a hereditary myeloid neoplasm. Germline DDX41 mutations are not uncommon and should be explored when treating the patients with myeloid malignancies.

Molecular basis of ETV6-mediated predisposition to childhood acute lymphoblastic leukemia

There is growing evidence supporting an inherited basis for susceptibility to acute lymphoblastic leukemia (ALL) in children. In particular, we and others reported recurrent germline ETV6 variants linked to ALL risk, which collectively represent a novel leukemia predisposition syndrome. To understand the influence of ETV6 variation on ALL pathogenesis, we comprehensively characterized a cohort of 32 childhood leukemia cases arising from this rare syndrome. Of 34 nonsynonymous germline ETV6 variants in ALL, we identified 22 variants with impaired transcription repressor activity, loss of DNA binding, and altered nuclear localization. Missense variants retained dimerization with wild-type ETV6 with potentially dominant-negative effects. Whole-transcriptome and whole-genome sequencing of this cohort of leukemia cases revealed a profound influence of germline ETV6 variants on leukemia transcriptional landscape, with distinct ALL subsets invoking unique patterns of somatic cooperating mutations. 70% of ALL cases with damaging germline ETV6 variants exhibited hyperdiploid karyotype with characteristic recurrent mutations in NRAS, KRAS, and PTPN11. In contrast, the remaining 30% cases had a diploid leukemia genome and an exceedingly high frequency of somatic copy-number loss of PAX5 and ETV6, with a gene expression pattern that strikingly mirrored that of ALL with somatic ETV6-RUNX1 fusion. Two ETV6 germline variants gave rise to both acute myeloid leukemia and ALL, with lineage-specific genetic lesions in the leukemia genomes. ETV6 variants compromise its tumor suppressor activity in vitro with specific molecular targets identified by assay for transposase-accessible chromatin sequencing profiling. ETV6-mediated ALL predisposition exemplifies the intricate interactions between inherited and acquired genomic variations in leukemia pathogenesis.

The Genomics of Myelodysplastic Syndromes: Origins of Disease Evolution, Biological Pathways, and Prognostic Implications

The molecular pathogenesis of myelodysplastic syndrome (MDS) is complex due to the high rate of genomic heterogeneity. Significant advances have been made in the last decade which elucidated the landscape of molecular alterations (cytogenetic abnormalities, gene mutations) in MDS. Seminal experimental studies have clarified the role of diverse gene mutations in the context of disease phenotypes, but the lack of faithful murine models and/or cell lines spontaneously carrying certain gene mutations have hampered the knowledge on how and why specific pathways are associated with MDS pathogenesis. Here, we summarize the genomics of MDS and provide an overview on the deregulation of pathways and the latest molecular targeted therapeutics.

Pediatric acute lymphoblastic leukemia

The last decade has witnessed great advances in our understanding of the genetic and biological basis of childhood acute lymphoblastic leukemia (ALL), the development of experimental models to probe mechanisms and evaluate new therapies, and the development of more efficacious treatment stratification. Genomic analyses have revolutionized our understanding of the molecular taxonomy of ALL, and these advances have led the push to implement genome and transcriptome characterization in the clinical management of ALL to facilitate more accurate risk-stratification and, in some cases, targeted therapy. Although mutation- or pathway-directed targeted therapy (e.g., using tyrosine kinase inhibitors to treat Philadelphia chromosome [Ph]-positive and Phlike B-cell-ALL) is currently available for only a minority of children with ALL, many of the newly identified molecular alterations have led to the exploration of approaches targeting deregulated cell pathways. The efficacy of cellular or humoral immunotherapy has been demonstrated with the success of chimeric antigen receptor T-cell therapy and the bispecific engager blinatumomab in treating advanced disease. This review describes key advances in our understanding of the biology of ALL and optimal approaches to risk-stratification and therapy, and it suggests key areas for basic and clinical research.

Functional characterization of a germline ETV6 variant associated with inherited thrombocytopenia, acute lymphoblastic leukemia, and salivary gland carcinoma in childhood

Germline pathogenic ETV6 variants have been discovered in families with inherited thrombocytopenia and predisposition to hematological and solid malignancies. We present a patient with short stature who was initially diagnosed with chronic immune thrombocytopenia. Subsequently, the patient developed acute lymphoblastic leukemia, followed by mammary analog secretory carcinoma. Sequencing analysis identified an ETV6 c.641C > T (p.Pro214Leu) germline variant. The variant protein exhibited attenuated nuclear localization, increased protein degradation, and reduced transcription repression function. Our findings suggest that the ETV6 gene should be sequenced in patients with inherited thrombocytopenia and malignancy, and emphasize the importance of careful follow-up to identify secondary cancer in patients with pathogenic ETV6 variants.

ETV6 gene aberrations in non-haematological malignancies: A review highlighting ETV6 associated fusion genes in solid tumors

ETV6 (translocation-Ets-leukemia virus) gene is a transcriptional repressor mainly involved in haematopoiesis and maintenance of vascular networks and has developed to be a major oncogene with the potential ability of forming fusion partners with many other genes with carcinogenic consequences. ETV6 fusions function primarily by constitutive activation of kinase activity of the fusion partners, modifications in the normal functions of ETV6 transcription factor, loss of function of ETV6 or the partner gene and activation of a proto-oncogene near the site of translocation. The role of ETV6 fusion gene in tumorigenesis has been well-documented and more variedly found in haematological malignancies. However, the role of the ETV6 oncogene in solid tumors has also risen to prominence due to an increasing number of cases being reported with this malignancy. Since, solid tumors can be well-targeted, the diagnosis of this genre of tumors based on ETV6 malignancy is of crucial importance for treatment. This review highlights the important ETV6 associated fusions in solid tumors along with critical insights as to existing and novel means of targeting it. A consolidation of novel therapies such as immune, gene, RNAi, stem cell therapy and protein degradation hitherto unused in the case of ETV6 solid tumor malignancies may open further therapeutic avenues.

The Biology of B-Progenitor Acute Lymphoblastic Leukemia

Genomic analyses have revolutionized our understanding of the biology of B-progenitor acute lymphoblastic leukemia (ALL). Studies of thousands of cases across the age spectrum have revised the taxonomy of B-ALL by identifying multiple new subgroups with diverse sequence and structural initiating events that vary substantially by age at diagnosis and prognostic significance. There is a growing appreciation of the role of inherited genetic variation in predisposition to ALL and drug responsiveness and of the nature of genetic variegation and clonal evolution that may be targeted for improved diagnostic, risk stratification, disease monitoring, and therapeutic intervention. This review provides an overview of the current state of knowledge of the genetic basis of B-ALL, with an emphasis on recent discoveries that have changed our approach to diagnosis and monitoring.

ETV6: A Candidate Gene for Predisposition to "Blend Pedigrees"? A Case Report from the NEXT-Famly Clinical Trial

Background

The identification of germline mutations in familial leukemia predisposition genes by next generation sequencing is of pivotal importance. Lately, some “blend pedigrees” characterized by both solid and hematologic malignancies have been described. Some genes were recognized as related to this double predisposition, while the involvement of others is still a matter of debate. ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known. Case Presentation. We present our recent experience in the identification of an ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known. ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known. ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known.

Conclusion

This evidence supports the involvement of ETV6 in the predisposition to both solid and hematologic neoplasia and the importance of the investigation of the noncoding regions of the genes as recently suggested by different expert groups.ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known.

Analysis of 153 115 patients with hematological malignancies refines the spectrum of familial risk

Estimating familial cancer risks is clinically important in being able to discriminate between individuals in the population at differing risk for malignancy. To gain insight into the familial risk for the different hematological malignancies and their possible inter-relationship, we analyzed data on more than 16 million individuals from the Swedish Family-Cancer Database. After identifying 153 115 patients diagnosed with a primary hematological malignancy, we quantified familial relative risks (FRRs) by calculating standardized incident ratios (SIRs) in 391 131 of their first-degree relatives. The majority of hematological malignancies showed increased FRRs for the same tumor type, with the highest FRRs being observed for mixed cellularity Hodgkin lymphoma (SIR, 16.7), lymphoplasmacytic lymphoma (SIR, 15.8), and mantle cell lymphoma (SIR, 13.3). There was evidence for pleiotropic relationships; notably, chronic lymphocytic leukemia was associated with an elevated familial risk for other B-cell tumors and myeloproliferative neoplasms. Collectively, these data provide evidence for shared etiological factors for many hematological malignancies and provide information for identifying individuals at increased risk, as well as informing future gene discovery initiatives.

Hematological Malignancies in Adults With a Family Predisposition

BACKGROUND

Some hematological malignancies arise in persons with a hereditary predisposition. The hereditary nature of these diseases often goes unrecognized, particularly when symptoms begin in adulthood.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

Many rare germline mutations have been identified that lead to acute leukemia and myelodysplastic syndromes. They differ from one another with respect to their penetrance, the age of onset of disease, and the clinical manifestations. In view of this heterogeneity, no uniform recommendations have yet been formulated for their diagnosis and treatment. The most common types of hematological malig- nancy with a hereditary predisposition are traceable to an underlying disturbance of DNA damage response and repair mechanisms and to mutations of hematological transcription factors. With regard to the selection of patients for testing, the con- sensus is that cytogenetic and molecular-genetic findings that are suspect for a hereditary predisposition, such as CEBPA and RUNX1 mutations, call for further investigation, as do any clinical features that are typical of tumor syndromes, or a positive family history. The knowledge that a hereditary predisposition may be present is highly stressful for patients; testing should only be carried out after the patient has received genetic counseling. The confirmation of a germline mutation always requires a comparison with healthy tissue. A fibroblast culture is recom- mended as the gold standard for this purpose.

CONCLUSION

The detection of a hereditary predisposition to hematological neoplasia is often relevant to treatment and follow-up care: for example, it may motivate early allogeneic stem-cell transplantation. Counseling, predictive testing, and follow-up care are available to the patients' relatives as well.

Inherited thrombocytopenia and platelet disorders with germline predisposition to myeloid neoplasia

Advances in molecular genetic sequencing techniques have contributed to the elucidation of previously unknown germline mutations responsible for inherited thrombocytopenia (IT). Regardless of age of presentation and severity of symptoms related to thrombocytopenia and/or platelet dysfunction, a subset of patients with IT are at increased risk of developing myeloid neoplasms during their life time, particularly those with germline autosomal dominant mutations in RUNX1, ANKRD26, and ETV6. Patients may present with isolated thrombocytopenia and megakaryocytic dysmorphia or atypia on baseline bone marrow evaluation, without constituting myelodysplasia (MDS). Bone marrow features may overlap with idiopathic thrombocytopenic purpura (ITP) or sporadic MDS leading to misdiagnosis. Progression to myelodysplastic syndrome/ acute myeloid leukemia (MDS/AML) may be accompanied by progressive bi- or pancytopenia, multilineage dysplasia, increased blasts, cytogenetic abnormalities, acquisition of bi-allelic mutations in the underlying gene with germline mutation, or additional somatic mutations in genes associated with myeloid malignancy. A subset of patients may present with MDS/AML at a young age, underscoring the growing concern for evaluating young patients with MDS/AML for germline mutations predisposing to myeloid neoplasm. Early recognition of germline mutation and predisposition to myeloid malignancy permits appropriate treatment, adequate monitoring for disease progression, proper donor selection for hematopoietic stem cell transplantation, as well as genetic counseling of the affected patients and their family members. Herein, we describe the clinical and diagnostic features of IT with germline mutations predisposing to myeloid neoplasms focusing on mutations involving RUNX1, ANKRD26, and ETV6.

Epidemiology of acute myeloid leukemia: Recent progress and enduring challenges

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

Inherited Platelet Disorders: A Modern Approach to Evaluation and Treatment

The inherited platelet disorders are a heterogeneous group of disorders that can be pleotropic in their clinical presentations. They may present with variable platelet counts and bleeding, making their diagnosis difficult. New diagnostic tools range from flow cytometric platelet function assessments to next-generation sequencing. Several platelet disorders may now be treated with gene therapy or bone marrow transplant. Improved understanding of the molecular and biologic mechanisms of the inherited platelet disorders may lead to novel targeted therapies.

Transcription factor mutations as a cause of familial myeloid neoplasms

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

Germline SAMD9 and SAMD9L mutations are associated with extensive genetic evolution and diverse hematologic outcomes

Germline SAMD9 and SAMD9L mutations cause a spectrum of multisystem disorders that carry a markedly increased risk of developing myeloid malignancies with somatic monosomy 7. Here, we describe 16 siblings, the majority of which were phenotypically normal, from 5 families diagnosed with myelodysplasia and leukemia syndrome with monosomy 7 (MLSM7; OMIM 252270) who primarily had onset of hematologic abnormalities during the first decade of life. Molecular analyses uncovered germline SAMD9L (n = 4) or SAMD9 (n = 1) mutations in these families. Affected individuals had a highly variable clinical course that ranged from mild and transient dyspoietic changes in the bone marrow to a rapid progression of myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) with monosomy 7. Expression of these gain-of-function SAMD9 and SAMD9L mutations reduces cell cycle progression, and deep sequencing demonstrated selective pressure favoring the outgrowth of clones that have either lost the mutant allele or acquired revertant mutations. The myeloid malignancies of affected siblings acquired cooperating mutations in genes that are also altered in sporadic cases of AML characterized by monosomy 7. These data have implications for understanding how SAMD9 and SAMD9L mutations contribute to myeloid transformation and for recognizing, counseling, and treating affected families.