Anna L. Brown

Inherited bone marrow failure syndromes (IBMFS) are monogenic disorders characterized by single or multilineage cytopenias from hypoproliferative dyshematopoiesis. Diagnosis is challenging because of substantial clinical and pathological overlap between individual IBMFS entities and acquired diseases such as immune aplastic anemia. Conventional genetic testing using targeted panels or whole exome sequencing incompletely captures the spectrum of pathogenic variation, leaving a substantial proportion of cases undiagnosed. We evaluated the utility of upfront whole genome and transcriptome sequencing (WGTS) in 237 patients with suspected IBMFS using non-hematopoietic DNA. Median age was 29 years (range 3 months-76 years) and 34.6% were under 18 years. Clinically-accredited sequencing was performed with real-time return of results to guide patient management and familial testing. A molecular diagnosis was established in 87/237 patients (36.7%), spanning hereditary thrombocytopenia, telomere biology disorders, Diamond-Blackfan anemia, severe congenital neutropenia, Shwachman-Diamond syndrome, Fanconi anemia and other IBMFS. A further four patients were diagnosed with non-hematological genetic conditions and seven patients with secondary actionable findings. Novel pathogenic mechanisms including retrotransposon-mediated gene disruption were identified. Further, novel associations with primary IBMFS-like presentations (THRA) as well as definitive evidence of gene-disease associations (MEIS1, TUBB) were established. Acceptability of WGTS based on the established Theoretical Framework of Acceptability was high among patients and carers. Upfront WGTS in suspected IBMFS provides a high diagnostic yield when compared with other genomic approaches, identifies actionable genomic abnormalities, and expands the spectrum of disease mechanisms and gene associations in IBMFS.

Germline GATA2 deficiency is a pleiotropic condition 1-8 characterized by numerous phenotypes, including monocytopenia, immunodeficiency, microbial susceptibilities, and high rates of myeloid malignancies 1,8. Accurate curation of germline GATA2 variants is critical for patient care and requires well-defined phenotypes associated with GATA2 deficiency. The many phenotypes attributed to the condition render a simple description of GATA2 deficiency difficult, complicating the development of GATA2 variant curation rules. Therefore, the Myeloid Malignancy Variant Curation Expert Panel (MM-VCEP) sought to define GATA2 deficiency based on a statistical comparison of phenotype data. To do so, the MM-VCEP systematically analyzed phenotype data and applied statistical comparisons to define the phenotypic features of GATA2 deficiency to inform germline variant curation. The MM-VCEP assembled an international cohort of 339 people with clinically diagnosed GATA2 deficiency from 16 centers in seven countries. The 73 phenotypes of these individuals were compared statistically to those of control participants from the UK Biobank (UKBB). We compared single phenotypes as well as combinations of two, three, and four phenotypes in people with clinically diagnosed GATA2 deficiency to UKBB controls. We defined GATA2 deficiency as any of the 2,903 combinations of two or three phenotypes with log10Odds Ratio ≥3 (OR ≥ 1000). This definition of GATA2 deficiency will inform gene-specific phenotypic criteria used in GATA2 variant curation guidelines that will facilitate standardized variant curation by clinical laboratories worldwide.

Purpose of Review Despite increased recognition of FPDMM and advancements in genetic technologies that have improved carrier identification and our understanding of RUNX1 function, the mechanisms driving hematologic malignancy (HM) development in this disorder remain incompletely understood. Currently, there are no FPDMM-specific therapeutic strategies, and clinical management is largely confined to surveillance and supportive measures. This review aims to summarise emerging therapeutic strategies across all stages of disease progression, from early preventive interventions to treatments post-malignant transformation. Recent Findings Recent studies have explored multiple experimental strategies addressing distinct aspects of RUNX1-FPDMM pathobiology. These include CRISPR/Cas9-mediated correction of pathogenic germline RUNX1 variants, approaches that stabilize or enhance RUNX1 protein function by preventing its degradation or inhibition, and modulation of deregulated signaling pathways downstream of RUNX1 dysfunction. In addition, emerging therapies aim to target high-risk somatic variants that arise during disease progression. Interventions directed at hyperactivated inflammatory pathways, including JAK1/2 and mTOR, have also shown potential in mitigating the proinflammatory environment that contributes to hematologic malignancy development in FPDMM. Summary Therapeutic approaches for FPDMM are multi-modal with approaches including; correcting pathogenic RUNX1 gene variants, enhancing RUNX1 protein stability and protection, and modulating signaling pathways disrupted by its dysfunction to normalise the underlying hematological disturbances. Although several agents are in clinical studies, all approaches are at an early stage and there remains much work to be done to translate treatments for clinical benefit.

This retrospective analysis aimed to provide evidence-based risk stratification of TP53-mutated (TP53mut) myeloid neoplasms (MNs). Of 580 MNs harboring TP53mut with variant allele frequency (VAF) ≥2%, 219 (37.8%), 194 (33.4%), 92 (15.9%), and 75 (12.9%) were classified as acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) with low blasts (MDS-LB), MDS with excess blasts (MDS-EB)-2, and -EB1 according to the revised fourth edition of the World Health Organization (WHO) classification, respectively. Hierarchical analysis identified the following 4 risk groups with distinct survival: (1) MDS-LB, (2) MDS-EB1/EB2/AML VAF <10%, (3) MDS-EB1/EB2 VAF ≥10%, and (4) AML VAF ≥10%. We next evaluated the impact of allelic status, VAF, and complex karyotype (CK). In our cohort, the significance of biallelic status was limited to MDS with <5% blasts and not for blasts 5% to 9%, as proposed by the International Consensus Classification (ICC), or 5% to 19%, as proposed by the fifth edition of the WHO (WHO-5). MDS-EB1 and -EB2 with VAF ≥10% had comparable survival (9.6 vs 7.2 months; P = .12), regardless of allelic status. Contrary to the ICC proposal, MDS-EB1/EB2 with VAF <10% and CK had poor survival compared with those without CK, comparable to MDS-EB1/EB2 with VAF ≥10% (5.6 vs 26.2 vs 6.3 months; P = .003). Survival of TP53mut AML was poor (median 3.9 months) regardless of allelic/CK status. Thus, using ICC or WHO-5 may underestimate prognosis of MDS with blasts 5% to 19% and 5% to 9%, respectively. Collectively, the hierarchical model acknowledges poor survival of 91.9% TP53mut MDS and AML compared with 36.5% and 80.7% by WHO-5 and ICC, respectively.

The World Health Organization (WHO-5) and International Consensus Classification (ICC) acknowledge the poor prognosis of TP53-mutated (TP53 ^mut) myeloid neoplasm (MN). However, there are substantial differences between the two classifications that may lead to under- or overestimation of the prognostic risk. We retrospectively applied WHO-5 and ICC to 603 MN cases harboring TP53 ^mut (variant allele frequency, VAF ≥ 2%). WHO-5 and ICC would not classify 64% and 20% of these cases as TP53 ^mut MN, respectively. Moreover, of those classified, 67.5% would be classified discrepantly. Primary drivers of discrepancies included: (i) prognostic importance of TP53 ^mut acute myeloid leukemia (AML), (ii) interaction of the blast percentage and allelic status, (iii) 17p.13.1 deletion detected by cytogenetics, (iv) complex karyotype (CK) as multi-hit equivalent, and (v) TP53 ^mut VAF threshold, we analyzed survival outcomes of each of these groups with an aim to provide clarity. TP53 ^mut AML was associated with significantly poor survival compared to TP53-wild type TP53 ^wt AML, myelodysplasia-related (AML, MR 4.7 vs. 18.3 months; P < 0.0001), supporting its inclusion within TP53 ^mut MN as a distinct subentity. Secondly, the survival of TP53 ^mut with blast 10–19% was poor regardless of the allelic status. Thirdly, for cases with a single TP53 ^mut with VAF < 50%, 17p13.1 del or CK serve as practical surrogates of biallelic inactivation, obviating the need for an additional copy number analysis. Finally, TP53 ^mut AML, MDS multi-hit/multi-hit equivalent with VAF < 10% had significantly poorer survival compared to TP53 ^mut MDS VAF < 10% without CK and 17p del, and were comparable to those with VAF ≥ 10% (14.1 vs. 48.8 vs.7.8 months, P < 0.0001). Collectively, these findings address key areas of contention and provide valuable insights that will guide future revisions of the WHO and ICC classifications.

The genomics era has facilitated the discovery of new genes that predispose individuals to bone marrow failure (BMF) and hematological malignancy (HM). We report the discovery of ETS-related gene (ERG), a novel, autosomal dominant BMF/HM predisposition gene. ERG is a highly constrained transcription factor that is critical for definitive hematopoiesis, stem cell function, and platelet maintenance. ERG colocalizes with other transcription factors, including RUNX family transcription factor 1 (RUNX1) and GATA binding protein 2 (GATA2), on promoters or enhancers of genes that orchestrate hematopoiesis. We identified a rare heterozygous ERG missense variant in 3 individuals with thrombocytopenia from 1 family and 14 additional ERG variants in unrelated individuals with BMF/HM, including 2 de novo cases and 3 truncating variants. Phenotypes associated with pathogenic germ line ERG variants included cytopenias (thrombocytopenia, neutropenia, and pancytopenia) and HMs (acute myeloid leukemia, myelodysplastic syndrome, and acute lymphoblastic leukemia) with onset before 40 years. Twenty ERG variants (19 missense and 1 truncating), including 3 missense population variants, were functionally characterized. Thirteen potentially pathogenic erythroblast transformation specific (ETS) domain missense variants displayed loss-of-function (LOF) characteristics, thereby disrupting transcriptional transactivation, DNA binding, and/or nuclear localization. Selected variants overexpressed in mouse fetal liver cells failed to drive myeloid differentiation and cytokine-independent growth in culture and to promote acute erythroleukemia when transplanted into mice, concordant with these being LOF variants. Four individuals displayed somatic genetic rescue by copy neutral loss of heterozygosity. Identification of predisposing germ line ERG variants has clinical implications for patient and family diagnoses, counseling, surveillance, and treatment strategies, including selection of bone marrow donors and cell or gene therapy.