Emerging Therapeutic Approaches for Diamond Blackfan Anemia.
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ABSTRACT:
SUBMITTER: Aspesi A
PROVIDER: S-EPMC6637096 | biostudies-literature | 2018
REPOSITORIES: biostudies-literature
Publications
Emerging Therapeutic Approaches for Diamond Blackfan Anemia.
Aspesi Anna A Borsotti Chiara C Follenzi Antonia A
Current gene therapy 20180101 6
Diamond Blackfan Anemia (DBA) is an inherited erythroid aplasia with onset in childhood. Patients carry heterozygous mutations in one of 19 Ribosomal Protein (RP) genes, that lead to defective ribosome biogenesis and function. Standard treatments include steroids or blood transfusions but the only definitive cure is allogeneic Hematopoietic Stem Cell Transplantation (HSCT). Although advances in HSCT have greatly improved the success rate over the last years, the risk of adverse events and mortal ...[more]
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Project description:Diamond-Blackfan anemia (DBA) was the first ribosomopathy described and is a constitutional inherited bone marrow failure syndrome. Erythroblastopenia is the major characteristic of the disease, which is a model for ribosomal diseases, related to a heterozygous allelic variation in 1 of the 20 ribosomal protein genes of either the small or large ribosomal subunit. The salient feature of classical DBA is a defect in ribosomal RNA maturation that generates nucleolar stress, leading to stabilization of p53 and activation of its targets, resulting in cell-cycle arrest and apoptosis. Although activation of p53 may not explain all aspects of DBA erythroid tropism, involvement of GATA1/HSP70 and globin/heme imbalance, with an excess of the toxic free heme leading to reactive oxygen species production, account for defective erythropoiesis in DBA. Despite significant progress in defining the molecular basis of DBA and increased understanding of the mechanistic basis for DBA pathophysiology, progress in developing new therapeutic options has been limited. However, recent advances in gene therapy, better outcomes with stem cell transplantation, and discoveries of putative new drugs through systematic drug screening using large chemical libraries provide hope for improvement.
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Project description:Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome, characterized as a rare congenital bone marrow erythroid hypoplasia (OMIM#105650). Erythroid defect in DBA results in erythroblastopenia in bone marrow as a consequence of maturation blockade between the burst forming unit-erythroid and colony forming unit-erythroid developmental stages, leading to moderate to severe usually macrocytic aregenerative (<20 × 109/L of reticulocytes) anemia. Congenital malformations localized mostly in the cephalic area and in the extremities (thumbs), as well as short stature and cardiac and urogenital tract abnormalities, are a feature of 50% of the DBA-affected patients. A significant increased risk for malignancy has been reported. DBA is due to a defect in the ribosomal RNA (rRNA) maturation as a consequence of a heterozygous mutation in 1 of the 20 ribosomal protein genes. Besides classical DBA, some DBA-like diseases have been identified. The relation between the defect in rRNA maturation and the erythroid defect in DBA has yet to be fully defined. However, recent studies have identified a role for GATA1 either due to a specific defect in its translation or due to its defective regulation by its chaperone HSP70. In addition, excess free heme-induced reactive oxygen species and apoptosis have been implicated in the DBA erythroid phenotype. Current treatment options are either regular transfusions with appropriate iron chelation or treatment with corticosteroids starting at 1 year of age. The only curative treatment for the anemia of DBA to date is bone marrow transplantation. Use of gene therapy as a therapeutic strategy is currently being explored.
| S-EPMC8791146 | biostudies-literature
Project description:Diamond Blackfan anemia (DBA) is an inherited bone marrow failure syndrome characterized by red cell aplasia and congenital anomalies. A predisposition to cancer has been suggested but not quantified by case reports. The DBA Registry of North America (DBAR) is the largest established DBA patient cohort, with prospective follow-up since 1991. This report presents the first quantitative assessment of cancer incidence in DBA. Among 608 patients with 9458 person-years of follow-up, 15 solid tumors, 2 acute myeloid leukemias, and 2 cases of myelodysplastic syndrome were diagnosed at a median age of 41 years in patients who had not received a bone marrow transplant. Cancer incidence in DBA was significantly elevated. The observed-to- expected ratio for all cancers combined was 5.4 (P < .05); significant observed-to-expected ratios were 287 for myelodysplastic syndrome, 28 for acute myeloid leukemia, 36 for colon carcinoma, 33 for osteogenic sarcoma, and 12 for female genital cancers. The median survival was 56 years, and the cumulative incidence of solid tumor/leukemia was approximately 20% by age 46 years. As in Fanconi anemia and dyskeratosis congenita, DBA is both an inherited bone marrow failure syndrome and a cancer predisposition syndrome; cancer risks appear lower in DBA than in Fanconi anemia or dyskeratosis congenita. This trial was registered at www.clinicaltrials.gov as #NCT00106015.
| S-EPMC3335385 | biostudies-literature
Project description:Diamond Blackfan Anemia (DBA) is a rare, congenital erythrocyte aplasia that is usually caused by haploinsufficiency of ribosomal proteins due to diverse mutations in one of several ribosomal protein genes. A striking feature of this disease is that a range of different mutations in ribosomal proteins results in similar disease phenotypes primarily characterized by erythrocyte abnormalities and macrocytic anemia, while most other cell types are minimally affected. Previously, we analyzed the erythrocyte membrane proteomes of several DBA patients and identified several proteins that are not typically associated with this cell type that suggested inflammatory mechanisms contribute to the pathogenesis of DBA. In this study, we evaluated the erythrocyte cytosolic proteome of DBA patients through in-depth analysis of hemoglobin-depleted erythrocyte cytosol. The simple, reproducible, hemoglobin depletion using nickel columns enabled in-depth analysis of over 1000 cytosolic erythrocyte proteins with minimal subsequent fractionation of the proteome. Label-free quantitation and statistical analysis identified 29 proteins that were significantly changed in DBA patients compared to matched healthy control donors. Some of the proteins that were significantly increased in DBA erythrocyte cytoplasm included three proteasome subunit beta proteins that make up the immunoproteasome and proteins induced by interferon-γ such as n-myc interactor and interferon-induced 25 kDa protein [NMI and IFI35 respectively]. Pathway analysis confirmed the presence of an inflammatory signature with erythrocytes of DBA patients and predicted key upstream regulators including mitogen activated kinase 1, interferon-γ, tumor suppressor p53, and tumor necrosis factor. These results show that erythrocytes in DBA patients are intrinsically different from those in healthy controls which may be due to an inflammatory response resulting from the inherent molecular defect of ribosomal protein haploinsufficiency or changes in the bone marrow microenvironment that leads to red cell aplasia in DBA patients.
2018-10-24 | PXD002339 | Pride
Project description:Diamond-Blackfan anemia is a rare inherited bone marrow failure syndrome (five to seven cases per million live births) characterized by an aregenerative, usually macrocytic anemia with an absence or less than 5% of erythroid precursors (erythroblastopenia) in an otherwise normal bone marrow. The platelet and the white cell counts are usually normal but neutropenia, thrombopenia or thrombocytosis have been noted at diagnosis. In 40 to 50% of DBA patients, congenital abnormalities mostly in the cephalic area and in thumbs and upper limbs have been described. Recent analysis did show a phenotype/genotype correlation. Congenital erythroblastopenia of DBA is the first human disease identified to result from defects in ribosomal biogenesis. The first ribosomal gene involved in DBA, ribosomal protein (RP) gene S19 (RPS19 gene), was identified in 1999. Subsequently, mutations in 12 other RP genes out of a total of 78 RP genes have been identified in DBA. All RP gene mutations described to date are heterozygous and dominant inheritance has been documented in 40 to 45% of affected individuals. As RP mutations are yet to be identified in approximately 50% of DBA cases, it is likely that other yet to be identified genes involved in ribosomal biogenesis or other pathways may be responsible for DBA phenotype.
| S-EPMC3699172 | biostudies-literature
Project description:Diamond Blackfan anemia (DBA) is a rare inherited bone marrow failure syndrome, the founding member of a class of disorders known as ribosomopathies. Most cases result from loss of function mutations or deletions in 1 of 23 genes encoding either a small or large subunit-associated ribosomal protein (RP), resulting in RP haploinsufficiency. DBA is characterized by red cell hypoplasia or aplasia, poor linear growth and congenital anomalies. Small case series and case reports demonstrate DBA to be a cancer predisposition syndrome. Recent analyses from the Diamond Blackfan Anemia Registry of North America (DBAR) have quantified the cancer risk in DBA. These studies reveal the most prevalent solid tumor, presenting in young adults and in children and adolescents, to be colorectal cancer (CRC) and osteogenic sarcoma, respectively. Of concern is that these cancers are typically detected at an advanced stage in patients who, because of their constitutional bone marrow failure, may not tolerate full-dose chemotherapy. Thus, the inability to provide optimal therapy contributes to poor outcomes. CRC screening in individuals over the age of 50 years, and now 45 years, has led to early detection and significant improvements in outcomes for non-DBA patients with CRC. These screening and surveillance strategies have been adapted to detect familial early onset CRC. With the recognition of DBA as a moderately penetrant cancer risk syndrome a rational screening and surveillance strategy will be implemented. The downstream molecular events, resulting from RP haploinsufficiency and leading to cancer, are the subject of significant scientific inquiry.
| S-EPMC8774389 | biostudies-literature
Project description:The gene encoding the ribosomal protein S19 (RPS19) is frequently mutated in Diamond-Blackfan anemia (DBA), a congenital erythroblastopenia. The consequence of these mutations on the onset of the disease remains obscure. Here, we show that RPS19 plays an essential role in biogenesis of the 40S small ribosomal subunit in human cells. Knockdown of RPS19 expression by siRNAs impairs 18S rRNA synthesis and formation of 40S subunits and induces apoptosis in HeLa cells. Pre-rRNA processing is altered, which leads to an arrest in the maturation of precursors to the 18S rRNA. Under these conditions, pre-40S particles are not exported to the cytoplasm and accumulate in the nucleoplasm of the cells in perinuclear dots. Consistently, we find that ribosome biogenesis and nucleolar organization is altered in skin fibroblasts from DBA patients bearing mutations in the RPS19 gene. In addition, maturation of the 18S rRNA is also perturbed in cells from a patient bearing no RPS19-related mutation. These results support the hypothesis that DBA is directly related to a defect in ribosome biogenesis and indicate that yet to be discovered DBA-related genes may be involved in the synthesis of the ribosomal subunits.
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Project description:Diamond-Blackfan anemia (DBA) is a rare bone marrow failure disorder that affects 7 out of 1,000,000 live births and has been associated with mutations in components of the ribosome. In order to characterize the genetic landscape of this heterogeneous disorder, we recruited a cohort of 472 individuals with a clinical diagnosis of DBA and performed whole-exome sequencing (WES). We identified relevant rare and predicted damaging mutations for 78% of individuals. The majority of mutations were singletons, absent from population databases, predicted to cause loss of function, and located in 1 of 19 previously reported ribosomal protein (RP)-encoding genes. Using exon coverage estimates, we identified and validated 31 deletions in RP genes. We also observed an enrichment for extended splice site mutations and validated their diverse effects using RNA sequencing in cell lines obtained from individuals with DBA. Leveraging the size of our cohort, we observed robust genotype-phenotype associations with congenital abnormalities and treatment outcomes. We further identified rare mutations in seven previously unreported RP genes that may cause DBA, as well as several distinct disorders that appear to phenocopy DBA, including nine individuals with biallelic CECR1 mutations that result in deficiency of ADA2. However, no new genes were identified at exome-wide significance, suggesting that there are no unidentified genes containing mutations readily identified by WES that explain >5% of DBA-affected case subjects. Overall, this report should inform not only clinical practice for DBA-affected individuals, but also the design and analysis of rare variant studies for heterogeneous Mendelian disorders.
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Project description:Ribosomal protein haploinsufficiency occurs in diverse human diseases including Diamond-Blackfan anemia (DBA), congenital asplenia and T cell leukemia. Yet, how mutations in genes encoding ubiquitously expressed proteins such as these result in cell-type- and tissue-specific defects remains unknown. Here, we identify mutations in GATA1, encoding the critical hematopoietic transcription factor GATA-binding protein-1, that reduce levels of full-length GATA1 protein and cause DBA in rare instances. We show that ribosomal protein haploinsufficiency, the more common cause of DBA, can lead to decreased GATA1 mRNA translation, possibly resulting from a higher threshold for initiation of translation of this mRNA in comparison with other mRNAs. In primary hematopoietic cells from patients with mutations in RPS19, encoding ribosomal protein S19, the amplitude of a transcriptional signature of GATA1 target genes was globally and specifically reduced, indicating that the activity, but not the mRNA level, of GATA1 is decreased in patients with DBA associated with mutations affecting ribosomal proteins. Moreover, the defective hematopoiesis observed in patients with DBA associated with ribosomal protein haploinsufficiency could be partially overcome by increasing GATA1 protein levels. Our results provide a paradigm by which selective defects in translation due to mutations affecting ubiquitous ribosomal proteins can result in human disease.
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