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Huang D, Jiang M, Zhu Y, Li D, Lu X, Gao J. A novel missense mutation in the MECOM gene in a Chinese boy with radioulnar synostosis with amegakaryocytic thrombocytopenia. BMC Pediatr 2024; 24:62. [PMID: 38245683 PMCID: PMC10799460 DOI: 10.1186/s12887-024-04552-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/11/2024] [Indexed: 01/22/2024] Open
Abstract
Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) type 2, caused by MDS1 and EVI1 complex locus (MECOM) gene mutations, is a rare inherited bone marrow failure syndrome (IBMFS) with skeletal anomalies, characterized by varying presentation of congenital thrombocytopenia (progressing to pancytopenia), bilateral proximal radioulnar synostosis, and other skeletal abnormalities. Due to limited knowledge and heterogenous manifestations, clinical diagnosis of the disease is challenging. Here we reported a novel MECOM mutation in a Chinese boy with typical clinical features for RUSAT-2. Trio-based whole exome sequencing of buccal swab revealed a novel heterozygous missense mutation in exon 11 of the MECOM gene (chr3:168818673; NM_001105078.3:c.2285G > A). The results strongly suggest that the variant was a germline mutation and disease-causing mutation. The patient received matched unrelated donor hematopoetic stem cell transplantation (HSCT). This finding was not only expanded the pathogenic mutation spectrum of MECOM gene, but also provided key information for clinical diagnosis and treatment of RUSAT-2.
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Affiliation(s)
- Duowen Huang
- Department of Pediatric Hematology and Oncology, West China Second University Hospital, Sichuan University, No. 20 Section 3, South Renmin Road, Chengdu, 610041, Sichuan Province, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, Sichuan Province, China
| | - Mingyan Jiang
- Department of Pediatric Hematology and Oncology, West China Second University Hospital, Sichuan University, No. 20 Section 3, South Renmin Road, Chengdu, 610041, Sichuan Province, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, Sichuan Province, China
| | - Yiping Zhu
- Department of Pediatric Hematology and Oncology, West China Second University Hospital, Sichuan University, No. 20 Section 3, South Renmin Road, Chengdu, 610041, Sichuan Province, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, Sichuan Province, China
| | - Dongjun Li
- Department of Pediatric Hematology and Oncology, West China Second University Hospital, Sichuan University, No. 20 Section 3, South Renmin Road, Chengdu, 610041, Sichuan Province, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, Sichuan Province, China
| | - Xiaoxi Lu
- Department of Pediatric Hematology and Oncology, West China Second University Hospital, Sichuan University, No. 20 Section 3, South Renmin Road, Chengdu, 610041, Sichuan Province, China.
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, Sichuan Province, China.
| | - Ju Gao
- Department of Pediatric Hematology and Oncology, West China Second University Hospital, Sichuan University, No. 20 Section 3, South Renmin Road, Chengdu, 610041, Sichuan Province, China.
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, Sichuan Province, China.
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2
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Ammeti D, Marzollo A, Gabelli M, Zanchetta ME, Tretti-Parenzan C, Bottega R, Capaci V, Biffi A, Savoia A, Bresolin S, Faleschini M. A novel mutation in MECOM affects MPL regulation in vitro and results in thrombocytopenia and bone marrow failure. Br J Haematol 2023; 203:852-859. [PMID: 37610030 DOI: 10.1111/bjh.19023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/21/2023] [Accepted: 07/21/2023] [Indexed: 08/24/2023]
Abstract
MECOM-associated syndrome (MECOM-AS) is a rare disease characterized by amegakaryocytic thrombocytopenia, progressive bone marrow failure, pancytopenia and radioulnar synostosis with high penetrance. The clinical phenotype may also include finger malformations, cardiac and renal alterations, hearing loss, B-cell deficiency and predisposition to infections. The syndrome, usually diagnosed in the neonatal period because of severe thrombocytopenia, is caused by mutations in the MECOM gene, encoding for the transcription factor EVI1. The mechanism linking the alteration of EVI1 function and thrombocytopenia is poorly understood. In a paediatric patient affected by severe thrombocytopenia, we identified a novel variant of the MECOM gene (p.P634L), whose effect was tested on pAP-1 enhancer element and promoters of targeted genes showing that the mutation impairs the repressive activity of the transcription factor. Moreover, we demonstrated that EVI1 controls the transcriptional regulation of MPL, a gene whose mutations are responsible for congenital amegakaryocytic thrombocytopenia (CAMT), potentially explaining the partial overlap between MECOM-AS and CAMT.
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Affiliation(s)
- Daniele Ammeti
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Antonio Marzollo
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
| | - Maria Gabelli
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | | | - Caterina Tretti-Parenzan
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | - Roberta Bottega
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Valeria Capaci
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Alessandra Biffi
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | - Anna Savoia
- Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
| | - Silvia Bresolin
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | - Michela Faleschini
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
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Xu N, Liu K, Yang Y, Li X, Zhong Y. Chinese patients with 3M syndrome: clinical manifestations and two novel pathogenic variants. Front Genet 2023; 14:1164936. [PMID: 37719700 PMCID: PMC10501862 DOI: 10.3389/fgene.2023.1164936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 07/31/2023] [Indexed: 09/19/2023] Open
Abstract
Background: 3M syndrome is a rare autosomal recessive disease, characterized by intrauterine and postnatal growth retardation, facial dysmorphism, large head circumference, and skeletal changes, has rarely been reported in the Chinese population. Methods: We describe the clinical manifestations and gene variants in four sporadic cases of 3M syndrome in Chinese individuals from different families. Results: All cases had significant growth retardation, relative macrocephaly, and typical facial features. Exome sequencing revealed that two patients with 3M syndrome had homozygous variants of the CUL7 gene: one novel pathogenic variant and one previously reported pathogenic variant; the other two patients were heterozygous for variants in OBSL1, one of which had not been reported previously. Clinical evaluation indicated that these Chinese patients with 3M syndrome shared similar recognizable features with those reported in patients of other ethnic backgrounds, but not all patients with 3M syndrome in this study had normal development milestones. Two patients underwent recombinant human growth hormone (rhGH) therapy and showed accelerated growth in the first 2 years; however, the growth rate slowed in the third year in one case. There were no obvious adverse reactions during rhGH treatment. Conclusion: We report one novel CUL7 and one novel OBSL1 mutation in patients with 3M syndrome. Children with short stature, specific facial features, and physical symptoms should be referred for genetic testing to obtain precise diagnosis and appropriate treatment. The effects of rhGH treatment on adult height requires long-term observation and study in a large sample.
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Affiliation(s)
- Ningan Xu
- Department of Child Healthcare, Hunan Children’s Hospital, University of South China, Changsha, Hunan, China
- The Laboratory of Developmental and Behavioral Pediatrics, Hunan Children’s Hospital Changsha, University of South China, Changsha, Hunan, China
| | - Kangxiang Liu
- Department of Child Healthcare, Hunan Children’s Hospital, University of South China, Changsha, Hunan, China
| | - Yongjia Yang
- The Laboratory of Genetics and Metabolism, Hunan Children’s Research Institute (HCRI), Hunan Children’s Hospital, University of South China, Changsha, China
| | - Xiaoming Li
- Department of Radiology, Hunan Children’s Hospital, University of South China, Changsha, Hunan, China
| | - Yan Zhong
- Department of Child Healthcare, Hunan Children’s Hospital, University of South China, Changsha, Hunan, China
- The Laboratory of Developmental and Behavioral Pediatrics, Hunan Children’s Hospital Changsha, University of South China, Changsha, Hunan, China
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4
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Voit RA, Sankaran VG. MECOM Deficiency: from Bone Marrow Failure to Impaired B-Cell Development. J Clin Immunol 2023:10.1007/s10875-023-01545-0. [PMID: 37407873 DOI: 10.1007/s10875-023-01545-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 06/26/2023] [Indexed: 07/07/2023]
Abstract
MECOM deficiency is a recently identified inborn error of immunity and inherited bone marrow failure syndrome caused by haploinsufficiency of the hematopoietic transcription factor MECOM. It is unique among inherited bone marrow failure syndromes, many of which present during later childhood or adolescence, because of the early age of onset and severity of the pancytopenia, emphasizing the importance and gene dose dependency of MECOM during hematopoiesis. B-cell lymphopenia and hypogammaglobulinemia have been described in a subset of patients with MECOM deficiency. While the mechanisms underlying the B-cell deficiency are currently unknown, recent work has provided mechanistic insights into the function of MECOM in hematopoietic stem cell (HSC) maintenance. MECOM binds to regulatory enhancers that control the expression of a network of genes essential for HSC maintenance and self-renewal. Heterozygous mutations, as seen in MECOM-deficient bone marrow failure, lead to dysregulated MECOM network expression. Extra-hematopoietic manifestations of MECOM deficiency, including renal and cardiac anomalies, radioulnar synostosis, clinodactyly, and hearing loss, have been reported. Individuals with specific genotypes have some of the systemic manifestations with isolated mild thrombocytopenia or without hematologic abnormalities, highlighting the tissue specificity of mutations in some MECOM domains. Those infants with MECOM-associated bone marrow failure require HSC transplantation for survival. Here, we review the expanding cohort of patient phenotypes and accompanying genotypes resulting in MECOM deficiency, and the proposed mechanisms underlying MECOM regulation of human HSC maintenance and B-cell development.
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Affiliation(s)
- Richard A Voit
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, 02115, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Vijay G Sankaran
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, 02115, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
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5
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Lozano Chinga MM, Bertuch AA, Afify Z, Dollerschell K, Hsu JI, John TD, Rao ES, Rowe RG, Sankaran VG, Shimamura A, Williams DA, Nakano TA. Expanded phenotypic and hematologic abnormalities beyond bone marrow failure in MECOM-associated syndromes. Am J Med Genet A 2023; 191:1826-1835. [PMID: 37067177 PMCID: PMC10330190 DOI: 10.1002/ajmg.a.63208] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/17/2023] [Accepted: 03/31/2023] [Indexed: 04/18/2023]
Abstract
The MECOM gene encodes multiple protein isoforms that are essential for hematopoietic stem cell self-renewal and maintenance. Germline MECOM variants have been associated with congenital thrombocytopenia, radioulnar synostosis and bone marrow failure; however, the phenotypic spectrum of MECOM-associated syndromes continues to expand and novel pathogenic variants continue to be identified. We describe eight unrelated patients who add to the previously known phenotypes and genetic defects of MECOM-associated syndromes. As each subject presented with unique MECOM variants, the series failed to demonstrate clear genotype-to-phenotype correlation but may suggest a role for additional modifiers that affect gene expression and subsequent phenotype. Recognition of the expanded hematologic and non-hematologic clinical features allows for rapid molecular diagnosis, early identification of life-threatening complications, and improved genetic counseling for families. A centralized international publicly accessible database to share annotated MECOM variants would advance their clinical interpretation and provide a foundation to perform functional MECOM studies.
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Affiliation(s)
- Michell M Lozano Chinga
- Primary Children's Hospital, University of Utah, Salt Lake City, Utah, USA
- University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Alison A Bertuch
- Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA
| | - Zeinab Afify
- Primary Children's Hospital, University of Utah, Salt Lake City, Utah, USA
| | - Kaylee Dollerschell
- Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Joanne I Hsu
- Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA
| | - Tami D John
- Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA
| | - Emily S Rao
- Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Robert Grant Rowe
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Vijay G Sankaran
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Akiko Shimamura
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - David A Williams
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Taizo A Nakano
- Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, Colorado, USA
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6
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Wall E, Forsyth J, Kinning E, Marton T. Fetal hydrops caused by a novel pathogenic MECOM variant. Prenat Diagn 2023; 43:717-720. [PMID: 37160698 DOI: 10.1002/pd.6353] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/26/2023] [Accepted: 03/30/2023] [Indexed: 05/11/2023]
Abstract
We report a fetus with hydrops, congenital heart disease and bilateral radioulnar synostosis caused by a novel pathogenic MECOM variant. The female fetus was referred for post-mortem examination after fetal hydrops and intrauterine death was diagnosed at 20 weeks gestation. Post-mortem examination confirmed fetal hydrops, pallor, truncus arteriosus and bilateral radioulnar synostosis. Trio whole genome sequencing analysis detected a novel de novo heterozygous pathogenic loss-of-function variant in MECOM (NM_004991), associated with a diagnosis of Radioulnar Synostosis with Amegakaryocytic Thrombocytopenia 2 (RUSAT-2). RUSAT-2 is a variable condition associated postnatally with bone marrow failure, radioulnar synostosis and congenital anomalies. RUSAT-2 is not currently associated with a prenatal phenotype or fetal demise, and was not present on diagnostic NHS prenatal gene panels at time of diagnosis. This case highlights the diagnostic value of detailed phenotyping with post-mortem examination, and of using a broad sequencing approach.
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Affiliation(s)
- Elizabeth Wall
- Department of Clinical Genetics, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Joan Forsyth
- West Midlands Regional Genetics Laboratory, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Esther Kinning
- Department of Clinical Genetics, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Tamás Marton
- Histopathology Department, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
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7
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Duan X, Shen F, Deng Y, Zhang J, Fang F, Luo Z, Chen Y, Yang Y. Novel Loss of Function (G15D) Mutation on RAC2 in a Family with Combined Immunodeficiency and Increased Levels of Immunoglobulin G, A, and E. J Clin Immunol 2023; 43:604-614. [PMID: 36459342 DOI: 10.1007/s10875-022-01411-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/20/2022] [Indexed: 12/04/2022]
Abstract
Ras-related C3 botulinum toxin substrate 2 (RAC2) is a small guanine nucleotide binding molecule that is exclusively expressed in hematopoietic cell lineages as a switcher. Based on in vivo and/or in vitro model experiments, RAC2 plays important roles in different cells through proliferation, secretion, and phagocytosis. It also performs a suppressing function in immunoglobulin (Ig) switching in Rac2-/- animals or cells. Several RAC2 natural mutations have been described in patients with primary immunodeficiency. RAC2 mutations can be classified into loss-of-function inactivating (LoF-I) and gain-of-function activating mutations according to their functional effects. Only two LoF-I mutations on RAC2 have been reported, including a dominant D57N mutation in several cases that exhibit granulocyte function defects and a recessive D56X mutation in cases with common variable immunodeficiency. Regardless of the type of mutation, most of the reported RAC2 mutant cases have shown reduced IgG, IgA, and IgM levels. Herein, we report on a family with three members that suffer from persistent HPV infection, recurrent respiratory infections, bronchiectasis, and autoimmune disease. The immunologic profile suggests that the family was affected by combined immunodeficiency (CID) with increased serum levels of IgG, IgA, and IgE. Exome sequencing identified a de novo RAC2 mutation (c.44G > A/p.G15D) that was co-segregated with the disease in the family. Gene functional experiments identified that such mutation results in reduced guanosine triphosphate binding activity and RAC2 protein expression. In patients' lymphocytes, impaired aggregation and proliferation effects, decreased mitochondrial membrane potential, and increased levels of cell apoptosis were observed, although no functional abnormalities were detected in neutrophils. To our knowledge, this study was the first to identify a LoF-I mutation of RAC2 affecting lymphocyte function that consequently led to CID and increased levels of serum IgG, IgE, and IgA. This study presents a novel subtype of RAC2-related immune disorder.
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Affiliation(s)
- Xiaojun Duan
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China
| | - Fang Shen
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China
| | - Yafei Deng
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China
| | - Jin Zhang
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China
| | - Fan Fang
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China
| | - Zhenqing Luo
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China
| | - Yanping Chen
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China.
| | - Yongjia Yang
- Hunan Children's Hospital & School of Pediatrics, Hengyang Medical School, University of South China, Hunan, 421001, China.
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Feurstein S. Emerging bone marrow failure syndromes- new pieces to an unsolved puzzle. Front Oncol 2023; 13:1128533. [PMID: 37091189 PMCID: PMC10119586 DOI: 10.3389/fonc.2023.1128533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/22/2023] [Indexed: 04/25/2023] Open
Abstract
Inherited bone marrow failure (BMF) syndromes are genetically diverse - more than 100 genes have been associated with those syndromes and the list is rapidly expanding. Risk assessment and genetic counseling of patients with recently discovered BMF syndromes is inherently difficult as disease mechanisms, penetrance, genotype-phenotype associations, phenotypic heterogeneity, risk of hematologic malignancies and clonal markers of disease progression are unknown or unclear. This review aims to shed light on recently described BMF syndromes with sparse concise data and with an emphasis on those associated with germline variants in ADH5/ALDH2, DNAJC21, ERCC6L2 and MECOM. This will provide important data that may help to individualize and improve care for these patients.
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