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1.
Haematologica ; 106(1): 11-13, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33386715
2.
Front Pediatr ; 8: 570084, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33194896

RESUMO

DNA damage response is essential to human physiology. A broad spectrum of pathologies are displayed by individuals carrying monoallelic or biallelic loss-of-function mutations in DNA damage repair genes. DNA repair syndromes with biallelic disturbance of essential DNA damage response pathways manifest early in life with multi-systemic involvement and a high propensity for hematologic and solid cancers, as well as bone marrow failure. In this review, we describe classic biallelic DNA repair cancer syndromes arising from faulty single- and double-strand DNA break repair, as well as dysfunctional DNA helicases. These clinical entities include xeroderma pigmentosum, constitutional mismatch repair deficiency, ataxia telangiectasia, Nijmegen breakage syndrome, deficiencies of DNA ligase IV, NHEJ/Cernunnos, and ERCC6L2, as well as Bloom, Werner, and Rothmund-Thompson syndromes. To give an in-depth understanding of these disorders, we provide historical overview and discuss the interplay between complex biology and heterogeneous clinical manifestations.

3.
Best Pract Res Clin Haematol ; 33(3): 101197, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33038986

RESUMO

Increasing awareness about germline predisposition and the widespread application of unbiased whole exome sequencing contributed to the discovery of new clinical entities with high risk for the development of haematopoietic malignancies. The revised 2016 WHO classification introduced a novel category of "myeloid neoplasms with germline predisposition" with GATA2, CEBPA, DDX41, RUNX1, ANKRD26 and ETV6 genes expanding the spectrum of hereditary myeloid neoplasms (MN). Since then, more germline causes of MN were identified, including SAMD9, SAMD9L, and ERCC6L2. This review describes the genetic and clinical spectrum of predisposition to MN. The main focus lies in delineation of phenotypes, genetics and management of GATA2 deficiency and the novel SAMD9/SAMD9L-related disorders. Combined, GATA2 and SAMD9/SAMD9L (SAMD9/9L) syndromes are recognized as most frequent causes of primary paediatric myelodysplastic syndromes, particularly in setting of monosomy 7. To date, ~550 cases with germline GATA2 mutations, and ~130 patients with SAMD9/9L mutations had been reported in literature. GATA2 deficiency is a highly penetrant disorder with a progressive course that often rapidly necessitates bone marrow transplantation. In contrast, SAMD9/9L disorders show incomplete penetrance with various clinical outcomes ranging from spontaneous haematological remission observed in young children to malignant progression.

4.
Br J Haematol ; 2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32744739

RESUMO

Dyskeratosis Congenita (DKC) is a systemic disorder caused by mutations resulting in impaired telomere maintenance. Clinical features include bone marrow failure and an increased risk of developing hematological malignancies. There are conflicting data whether androgen derivatives (AD) can elongate telomeres in vivo and whether AD treatment enhances the risk of gaining myelodysplastic syndrome-related mutations. Seven TERC or TERT-mutated DKC patients underwent AD treatment. All patients revealed hematological response. Telomere length of lymphocytes and granulocytes increased significantly and no MDS-related mutations were detected. Pending longer follow-up, treatment with AD seems to represent an efficient and safe therapy for DKC patients.

5.
Pediatr Blood Cancer ; 67(10): e28652, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32779892

RESUMO

BACKGROUND: Myelodysplastic syndromes (MDS) represent a group of clonal hematopoietic stem cell disorders that commonly progress to acute myeloid leukemia (AML). The diagnostics, prognostics, and treatment of adult MDS are established but do not directly translate to children and adolescents. Pediatric MDS is a rare disease, characterized by unique cytogenetics and histology compared with adult MDS, and often arises secondary to germline predisposition or cytotoxic exposures. Our objective was to highlight aspects of diagnosis/management that would benefit from further systematic review toward the development of clinical practice guidelines for pediatric MDS. PROCEDURE: The North American Pediatric Aplastic Anemia Consortium (NAPAAC) is composed of collaborative institutions with a strong interest in pediatric bone marrow failure syndromes and hematologic malignancies. The NAPAAC MDS working group developed a national survey distributed to 35 NAPAAC institutions to assess data on (1) clinical presentation of pediatric MDS, (2) diagnostic evaluation, (3) criteria for diagnosis, (4) supportive care and treatment decisions, and (5) role of hematopoietic stem cell transplantation (HSCT). RESULTS: Twenty-eight of 35 institutions returned the survey. Most centers agreed on a common diagnostic workup, though there was considerable variation regarding the criteria for diagnosis. Although there was consensus on supportive care, treatment strategies, including the role of cytoreduction and HSCT, varied across centers surveyed. CONCLUSIONS: There is lack of national consensus on diagnosis and treatment of pediatric MDS. This survey identified key aspects of MDS management that will warrant systematic review toward the goal of developing national clinical practice guidelines for pediatric MDS.

7.
Leukemia ; 34(10): 2673-2687, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32555368

RESUMO

Deficiency of the transcription factor GATA2 is a highly penetrant genetic disorder predisposing to myelodysplastic syndromes (MDS) and immunodeficiency. It has been recognized as the most common cause underlying primary MDS in children. Triggered by the discovery of a recurrent synonymous GATA2 variant, we systematically investigated 911 patients with phenotype of pediatric MDS or cellular deficiencies for the presence of synonymous alterations in GATA2. In total, we identified nine individuals with five heterozygous synonymous mutations: c.351C>G, p.T117T (N = 4); c.649C>T, p.L217L; c.981G>A, p.G327G; c.1023C>T, p.A341A; and c.1416G>A, p.P472P (N = 2). They accounted for 8.2% (9/110) of cases with GATA2 deficiency in our cohort and resulted in selective loss of mutant RNA. While for the hotspot mutation (c.351C>G) a splicing error leading to RNA and protein reduction was identified, severe, likely late stage RNA loss without splicing disruption was found for other mutations. Finally, the synonymous mutations did not alter protein function or stability. In summary, synonymous GATA2 substitutions are a new common cause of GATA2 deficiency. These findings have broad implications for genetic counseling and pathogenic variant discovery in Mendelian disorders.


Assuntos
Deficiência de GATA2/genética , Fator de Transcrição GATA2/deficiência , Fator de Transcrição GATA2/genética , RNA/genética , Mutação Silenciosa/genética , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença/genética , Mutação em Linhagem Germinativa/genética , Heterozigoto , Humanos , Síndromes de Imunodeficiência/genética , Masculino , Síndromes Mielodisplásicas/genética , Fenótipo , Adulto Jovem
8.
Blood Adv ; 4(8): 1760-1769, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32343795

RESUMO

Diamond-Blackfan anemia (DBA) is a congenital pure red cell aplasia associated with congenital abnormalities and cancer predisposition. Allogeneic hematopoietic stem cell transplantation (HSCT) can correct the hematological phenotype and is indicated in transfusion-dependent patients. In 70 children reported to the German DBA and French HSCT registries, HSCT was performed from 1985 to 2017. Median age at HSCT was 5.5 years (range, 0.9-17.3 years). Two-thirds of patients (64%) were transplanted from a matched sibling donor (MSD), and most procedures were performed after the year 1999 (73%). Primary engraftment was achieved in all patients. One patient developed secondary graft failure. Cumulative incidence of acute graft-versus-host disease (GVHD) was 24% for °II-IV (95% confidence interval [CI], 16% to 37%) and 7% for °III-IV (95% CI, 3% to 17%); cumulative incidence of chronic GVHD was 11% (95% CI, 5% to 22%). The probability of chronic GVHD-free survival (cGFS) was 87% (95% CI, 79% to 95%) and significantly improved over time (<2000: 68% [95% CI, 47% to 89%] vs ≥2000: 94% [95% CI, 87% to 100%], P < .01). cGFS was comparable following HSCT from a MSD and an unrelated donor (UD). Of note, no severe chronic GVHD or deaths were reported following MSD-HSCT after 1999. The difference of cGFS in children transplanted <10 years of age compared with older patients did not reach statistical significance (<10 years: 90% [95% CI, 81% to 99%] vs 10-18 years 78% [95% CI, 58% to 98%]). In summary, these data indicate that HSCT is efficient and safe in young DBA patients and should be considered if a MSD or matched UD is available. HSCT for transfusion dependency only must be critically discussed in older patients.

9.
J Clin Invest ; 130(6): 2827-2844, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32338640

RESUMO

Inherited bone marrow failure syndromes (IBMFSs) are a heterogeneous group of disorders characterized by defective hematopoiesis, impaired stem cell function, and cancer susceptibility. Diagnosis of IBMFS presents a major challenge due to the large variety of associated phenotypes, and novel, clinically relevant biomarkers are urgently needed. Our study identified nuclear interaction partner of ALK (NIPA) as an IBMFS gene, as it is significantly downregulated in a distinct subset of myelodysplastic syndrome-type (MDS-type) refractory cytopenia in children. Mechanistically, we showed that NIPA is major player in the Fanconi anemia (FA) pathway, which binds FANCD2 and regulates its nuclear abundance, making it essential for a functional DNA repair/FA/BRCA pathway. In a knockout mouse model, Nipa deficiency led to major cell-intrinsic defects, including a premature aging phenotype, with accumulation of DNA damage in hematopoietic stem cells (HSCs). Induction of replication stress triggered a reduction in and functional decline of murine HSCs, resulting in complete bone marrow failure and death of the knockout mice with 100% penetrance. Taken together, the results of our study add NIPA to the short list of FA-associated proteins, thereby highlighting its potential as a diagnostic marker and/or possible target in diseases characterized by hematopoietic failure.

10.
Haematologica ; 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32241839

RESUMO

Diamond Blackfan anemia (DBA) is predominantly an autosomal dominant inherited red cell aplasia primarily caused by pathogenic germline variants in ribosomal protein genes. DBA due to pathogenic RPL35A variants has been associated with large 3q29 deletions and phenotypes not common in DBA. We conducted a multi-institutional genotype-phenotype study of 45 patients with DBA associated with pathogenic RPL35A germline variants and curated the variant data on 21 additional cases from the literature. Genotype-phenotype analyses were conducted comparing patients with large deletions versus all other pathogenic variants in RPL35A. Twenty-two of the 45 cases had large deletions in RPL35A. After adjusting for multiple tests, a statistically significant association was observed between patients with a large deletion and steroid-resistant anemia, neutropenia, craniofacial abnormalities, chronic gastrointestinal problems, and intellectual disabilities (p<0.01) compared with all other pathogenic variants. Non-large deletion pathogenic variants were spread across RPL35A with no apparent hot spot and 56% of the individual family variants were observed more than once. In this, the largest known study of DBA patients with pathogenic RPL35A variants, we determined that patients with large deletions have a more severe phenotype that is clinically different from those with non-large deletion variants. Genes of interest also deleted in the 3q29 region that could be associated with some of these phenotypic features include LMLN and IQCG. Management of DBA due to large RPL35A deletions may be challenging due to complex problems and require comprehensive assessments by multiple specialists including immunologic, gastrointestinal, and developmental evaluations to provide optimal multidisciplinary care.

11.
Am J Hematol ; 95(5): 472-482, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32043619

RESUMO

Pyruvate kinase (PK) deficiency is a rare recessive congenital hemolytic anemia caused by mutations in the PKLR gene. This study reports the molecular features of 257 patients enrolled in the PKD Natural History Study. Of the 127 different pathogenic variants detected, 84 were missense and 43 non-missense, including 20 stop-gain, 11 affecting splicing, five large deletions, four in-frame indels, and three promoter variants. Within the 177 unrelated patients, 35 were homozygous and 142 compound heterozygous (77 for two missense, 48 for one missense and one non-missense, and 17 for two non-missense variants); the two most frequent mutations were p.R510Q in 23% and p.R486W in 9% of mutated alleles. Fifty-five (21%) patients were found to have at least one previously unreported variant with 45 newly described mutations. Patients with two non-missense mutations had lower hemoglobin levels, higher numbers of lifetime transfusions, and higher rates of complications including iron overload, extramedullary hematopoiesis, and pulmonary hypertension. Rare severe complications, including lower extremity ulcerations and hepatic failure, were seen more frequently in patients with non-missense mutations or with missense mutations characterized by severe protein instability. The PKLR genotype did not correlate with the frequency of complications in utero or in the newborn period. With ICCs ranging from 0.4 to 0.61, about the same degree of clinical similarity exists within siblings as it does between siblings, in terms of hemoglobin, total bilirubin, splenectomy status, and cholecystectomy status. Pregnancy outcomes were similar across genotypes in PK deficient women. This report confirms the wide genetic heterogeneity of PK deficiency.


Assuntos
Anemia Hemolítica Congênita não Esferocítica/genética , Estudos de Associação Genética/métodos , Piruvato Quinase/deficiência , Erros Inatos do Metabolismo dos Piruvatos/genética , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Piruvato Quinase/genética , Adulto Jovem
12.
J Pediatr Hematol Oncol ; 42(4): e235-e237, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-30933022

RESUMO

Diamond-Blackfan Anemia (DBA) is a rare inherited form of pure red cell aplasia that usually manifests in infancy or early childhood, and is characterized by normochromic macrocytic anemia and bone marrow erythroblastopenia. The majority of DBA cases are associated with mutations in ribosomal protein genes. Here, we describe a Lebanese girl with RPL5-mutated DBA unresponsive to steroid treatment who died from complications following late hematopoietic stem cell transplantation performed at the age of 15 years.


Assuntos
Anemia de Diamond-Blackfan/genética , Sequência de Bases , Resistência a Medicamentos/genética , Mutação da Fase de Leitura , Proteínas Ribossômicas/genética , Deleção de Sequência , Adolescente , Aloenxertos , Anemia de Diamond-Blackfan/terapia , Criança , Pré-Escolar , Evolução Fatal , Feminino , Transplante de Células-Tronco Hematopoéticas , Humanos , Recém-Nascido , Líbano , Esteroides
13.
Nucleic Acids Res ; 48(2): 770-787, 2020 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-31799629

RESUMO

Variants in ribosomal protein (RP) genes drive Diamond-Blackfan anemia (DBA), a bone marrow failure syndrome that can also predispose individuals to cancer. Inherited and sporadic RP gene variants are also linked to a variety of phenotypes, including malignancy, in individuals with no anemia. Here we report an individual diagnosed with DBA carrying a variant in the 5'UTR of RPL9 (uL6). Additionally, we report two individuals from a family with multiple cancer incidences carrying a RPL9 missense variant. Analysis of cells from these individuals reveals that despite the variants both driving pre-rRNA processing defects and 80S monosome reduction, the downstream effects are remarkably different. Cells carrying the 5'UTR variant stabilize TP53 and impair the growth and differentiation of erythroid cells. In contrast, ribosomes incorporating the missense variant erroneously read through UAG and UGA stop codons of mRNAs. Metabolic profiles of cells carrying the 5'UTR variant reveal an increased metabolism of amino acids and a switch from glycolysis to gluconeogenesis while those of cells carrying the missense variant reveal a depletion of nucleotide pools. These findings indicate that variants in the same RP gene can drive similar ribosome biogenesis defects yet still have markedly different downstream consequences and clinical impacts.


Assuntos
Anemia de Diamond-Blackfan/genética , Processamento Pós-Transcricional do RNA/genética , Proteínas Ribossômicas/genética , Ribossomos/genética , Regiões 5' não Traduzidas/genética , Adolescente , Adulto , Anemia de Diamond-Blackfan/patologia , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Criança , Células Eritroides , Feminino , Humanos , Masculino , Mutação/genética , Precursores de RNA/genética , RNA Mensageiro/genética , Sequenciamento Completo do Exoma
14.
Am J Hum Genet ; 104(6): 1040-1059, 2019 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-31079900

RESUMO

The heterogeneous nuclear ribonucleoprotein (HNRNP) genes code for a set of RNA-binding proteins that function primarily in the spliceosome C complex. Pathogenic variants in these genes can drive neurodegeneration, through a mechanism involving excessive stress-granule formation, or developmental defects, through mechanisms that are not known. Here, we report four unrelated individuals who have truncating or missense variants in the same C-terminal region of hnRNPR and who have multisystem developmental defects including abnormalities of the brain and skeleton, dysmorphic facies, brachydactyly, seizures, and hypoplastic external genitalia. We further identified in the literature a fifth individual with a truncating variant. RNA sequencing of primary fibroblasts reveals that these HNRNPR variants drive significant changes in the expression of several homeobox genes, as well as other transcription factors, such as LHX9, TBX1, and multiple HOX genes, that are considered fundamental regulators of embryonic and gonad development. Higher levels of retained intronic HOX sequences and lost splicing events in the HOX cluster are observed in cells carrying HNRNPR variants, suggesting that impaired splicing is at least partially driving HOX deregulation. At basal levels, stress-granule formation appears normal in primary and transfected cells expressing HNRNPR variants. However, these cells reveal profound recovery defects, where stress granules fail to disassemble properly, after exposure to oxidative stress. This study establishes an essential role for HNRNPR in human development and points to a mechanism that may unify other "spliceosomopathies" linked to variants that drive multi-system congenital defects and are found in hnRNPs.


Assuntos
Deficiências do Desenvolvimento/etiologia , Fibroblastos/patologia , Regulação da Expressão Gênica , Genes Homeobox/genética , Ribonucleoproteínas Nucleares Heterogêneas/genética , Mutação , Processamento de RNA/genética , Criança , Pré-Escolar , Deficiências do Desenvolvimento/patologia , Feminino , Fibroblastos/metabolismo , Humanos , Lactente , Masculino , Estresse Oxidativo , Fenótipo , Sequenciamento Completo do Exoma
15.
J Exp Med ; 216(5): 1050-1060, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-30914438

RESUMO

Studies of allelic variation underlying genetic blood disorders have provided important insights into human hematopoiesis. Most often, the identified pathogenic mutations result in loss-of-function or missense changes. However, assessing the pathogenicity of noncoding variants can be challenging. Here, we characterize two unrelated patients with a distinct presentation of dyserythropoietic anemia and other impairments in hematopoiesis associated with an intronic mutation in GATA1 that is 24 nucleotides upstream of the canonical splice acceptor site. Functional studies demonstrate that this single-nucleotide alteration leads to reduced canonical splicing and increased use of an alternative splice acceptor site that causes a partial intron retention event. The resultant altered GATA1 contains a five-amino acid insertion at the C-terminus of the C-terminal zinc finger and has no observable activity. Collectively, our results demonstrate how altered splicing of GATA1, which reduces levels of the normal form of this master transcription factor, can result in distinct changes in human hematopoiesis.


Assuntos
Processamento Alternativo/genética , Anemia Diseritropoética Congênita/genética , Fator de Transcrição GATA1/genética , Hematopoese/genética , Íntrons/genética , Mutação de Sentido Incorreto , Síndromes Mielodisplásicas/genética , Adulto , Criança , Éxons , Células HEK293 , Células-Tronco Hematopoéticas/metabolismo , Humanos , Masculino , Síndromes Mielodisplásicas/patologia , Sítios de Splice de RNA/genética , Transcrição Genética/genética , Transfecção
16.
SLAS Discov ; 24(3): 304-313, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30784369

RESUMO

Diamond-Blackfan anemia (DBA) is a bone marrow failure syndrome caused by mutations in ribosomal protein genes. Pathogenic mechanisms are poorly understood but involve severely reduced proliferation of erythroid precursors. Because current DBA therapies are ineffective and associated with severe side effects, disease-specific therapies are urgently needed. We hypothesized that druggable molecular pathways underlying the defect can be revealed through phenotypic small-molecule screens. Accordingly, a screening assay was developed using c-kit+ fetal liver erythroid progenitors from a doxycycline-inducible DBA mouse model. The addition of doxycycline to the culture medium induces the phenotype and reduces proliferation to <10% of normal, such that rescue of proliferation can be used as a simple readout for screening. Here, we describe the assay rationale and efforts toward validation of a microtiter plate-compatible assay and its application in a pilot screen of 3871 annotated compounds. Ten hits demonstrated concentration-dependent activity, and we report a brief follow-up of one of these compounds. In conclusion, we established a robust scalable assay for screening molecules that rescue erythropoiesis in DBA.


Assuntos
Anemia de Diamond-Blackfan/tratamento farmacológico , Fenótipo , Anemia de Diamond-Blackfan/patologia , Animais , Transplante de Medula Óssea , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Doxiciclina/farmacologia , Doxiciclina/uso terapêutico , Ensaios de Triagem em Larga Escala , Humanos , Camundongos , Camundongos Endogâmicos C57BL
19.
Artigo em Inglês | MEDLINE | ID: mdl-30559313

RESUMO

Diamond-Blackfan Anemia (DBA) is a rare polygenic disorder defined by congenital hypoplastic anemia with marked decrease or absence of bone marrow erythroid precursors. Identifying the specific genetic etiology is important for counseling and clinical management. A 6-yr-old boy with a clinical diagnosis of DBA has been followed by our pediatric hematology team since birth. His clinical course includes transfusion-dependent hypoplastic anemia and progressive autoimmune cytopenias. Genetic testing failed to identify a causative mutation in any of the classical DBA-associated genes. He and his parents underwent trio whole-exome sequencing (WES) with no genetic etiology identified initially. Clinical persistence and suspicion led to testing for adenosine deaminase 2 (ADA2) activity and whole-genome sequencing (WGS) that identified compound heterozygous pathogenic mutations in the ADA2-encoding CECR1 gene, a recently appreciated etiology for congenital hypoplastic anemia. This case illustrates current challenges in genetic testing and how they can be overcome by multidisciplinary expertise in clinical medicine and genomics.


Assuntos
Adenosina Desaminase/genética , Anemia de Diamond-Blackfan/genética , Anemia Hipoplástica Congênita/genética , Peptídeos e Proteínas de Sinalização Intercelular/genética , Anemia de Diamond-Blackfan/diagnóstico , Anemia Hipoplástica Congênita/diagnóstico , Medula Óssea/fisiopatologia , Criança , Testes Genéticos/métodos , Humanos , Masculino , Mutação , Pais , Proteínas Ribossômicas , Sequenciamento Completo do Exoma
20.
Sci Rep ; 8(1): 17227, 2018 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-30442972

RESUMO

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

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