Somatic mutations in aplastic anemia: Significance for classification, therapy, and outcome.
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ABSTRACT:
SUBMITTER: Wood HJ
PROVIDER: S-EPMC8925687 | biostudies-literature | 2019 Jun
REPOSITORIES: biostudies-literature
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Somatic mutations in aplastic anemia: Significance for classification, therapy, and outcome.
Wood Henry J HJ Marsh Judith C W JCW
HemaSphere 20190630 Suppl
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Project description:BACKGROUND:In patients with acquired aplastic anemia, destruction of hematopoietic cells by the immune system leads to pancytopenia. Patients have a response to immunosuppressive therapy, but myelodysplastic syndromes and acute myeloid leukemia develop in about 15% of the patients, usually many months to years after the diagnosis of aplastic anemia. METHODS:We performed next-generation sequencing and array-based karyotyping using 668 blood samples obtained from 439 patients with aplastic anemia. We analyzed serial samples obtained from 82 patients. RESULTS:Somatic mutations in myeloid cancer candidate genes were present in one third of the patients, in a limited number of genes and at low initial variant allele frequency. Clonal hematopoiesis was detected in 47% of the patients, most frequently as acquired mutations. The prevalence of the mutations increased with age, and mutations had an age-related signature. DNMT3A-mutated and ASXL1-mutated clones tended to increase in size over time; the size of BCOR- and BCORL1-mutated and PIGA-mutated clones decreased or remained stable. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and longer and a higher rate of overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes. However, clonal dynamics were highly variable and might not necessarily have predicted the response to therapy and long-term survival among individual patients. CONCLUSIONS:Clonal hematopoiesis was prevalent in aplastic anemia. Some mutations were related to clinical outcomes. A highly biased set of mutations is evidence of Darwinian selection in the failed bone marrow environment. The pattern of somatic clones in individual patients over time was variable and frequently unpredictable. (Funded by Grant-in-Aid for Scientific Research and others.).
| S-EPMC7478337 | biostudies-literature
Project description:Aplastic anemia (AA) is a potentially fatal bone marrow failure syndrome characterized by a paucity of hematopoietic stem cells and progenitor cells with varying degrees of cytopenia and fatty infiltration of the bone marrow space. Recent advances in genomics have uncovered a link between somatic mutations and myeloid cancer in AA patients. At present, the impact of these mutations on AA patients remains uncertain. We retrospectively investigated 279 AA patients and 174 patients with myelodysplastic syndromes (MDS) and performed targeted sequencing of 22 genes on their bone marrow cells using next-generation sequencing (NGS). Associations of somatic mutations with prognostic relevance and response to treatment were analyzed. Of 279 AA patients, 25 (9.0%) patients had somatic mutations, and 20 (7.2%) patients had one mutation. The most frequently mutated genes were ASXL1(3.2% of the patients), DNMT3A (1.8%) and TET2 (1.8%). In the MDS group, somatic mutations were detected in 120 of 174 (69.0%) patients, and 81 patients (46.6%) had more than one mutation. The most frequently mutated genes were U2AF1 (24.7% of the patients), ASXL1 (18.4%) and TP53 (13.2%). Compared with MDS patients, AA patients had a significantly lower frequency of somatic mutations and mostly one mutation. Similarly, the median variant allele frequency was lower in AA patients than in MDS patients (6.9% vs. 28.4%). The overall response of 3 and 6 months in the somatic mutation (SM) group was 37.5% and 66.7%, respectively. Moreover, there was no significant difference compared with the no somatic mutation (N-SM) group. During the 2-years follow-up period, four (20%) deaths occurred in the SM group and 40 (18.1%) in the N-SM group, with no significant difference in overall survival and event-free survival between the two groups. Our data indicated that myeloid tumor-associated somatic mutations in AA patients were detected in only a minority of patients by NGS. AA and MDS patients had different gene mutation patterns. The somatic mutations in patients with AA were characterized by lower mutation frequency, mostly one mutation, and lower median allelic burden of mutations than MDS. Somatic mutations were a common finding in the elderly, and the frequency of mutations increases with age. The platelet count affected the treatment response at 3 months, and ferritin level affected the outcome at 6 months, while somatic mutations were not associated with treatment response or long-term survival. However, our cohort of patients with the mutation was small; this result needs to be further confirmed with large patient sample.
| S-EPMC10725342 | biostudies-literature
Project description:The prevalence and functional impact of somatic mutations in nonleukemic T cells is not well characterized, although clonal T-cell expansions are common. In immune-mediated aplastic anemia (AA), cytotoxic T-cell expansions are shown to participate in disease pathogenesis. We investigated the mutation profiles of T cells in AA by a custom panel of 2533 genes. We sequenced CD4+ and CD8+ T cells of 24 AA patients and compared the results to 20 healthy controls and whole-exome sequencing of 37 patients with AA. Somatic variants were common both in patients and healthy controls but enriched to AA patients' CD8+ T cells, which accumulated most mutations on JAK-STAT and MAPK pathways. Mutation burden was associated with CD8+ T-cell clonality, assessed by T-cell receptor beta sequencing. To understand the effect of mutations, we performed single-cell sequencing of AA patients carrying STAT3 or other mutations in CD8+ T cells. STAT3 mutated clone was cytotoxic, clearly distinguishable from other CD8+ T cells, and attenuated by successful immunosuppressive treatment. Our results suggest that somatic mutations in T cells are common, associate with clonality, and can alter T-cell phenotype, warranting further investigation of their role in the pathogenesis of AA.
| S-EPMC8102188 | biostudies-literature
Project description:In this study, we investigated somatic mutations of CD4+ and CD8+ T cells in patients with immune-mediated aplastic anemia (AA). To understand the role of mutations, we performed single-cell level analysis of 6 longitudinal samples of 2 AA patients carrying STAT3 or KRAS and other mutations in CD8+ T cells. The analysis was performed using V(D)J and 5' gene expression platform (10X Genomics). STAT3 mutated clone was clearly distinguishable from other CD8+ T cells and showed a cytotoxic phenotype, attenuated by successful immunosuppressive treatment. Our results suggest that somatic mutations in T cells can alter T cell phenotype warranting further investigation of their role in the pathogenesis of immune-mediated AA.
2021-03-24 | E-MTAB-9969 | biostudies-arrayexpress
Project description:Quality of response to immunosuppressive therapy and long-term outcomes for pediatric severe aplastic anemia remain incompletely characterized. Contemporary evidence to inform treatment of relapsed or refractory severe aplastic anemia for pediatric patients is also limited. The clinical features and outcomes for 314 children treated from 2002 to 2014 with immunosuppressive therapy for acquired severe aplastic anemia were analyzed retrospectively from 25 institutions in the North American Pediatric Aplastic Anemia Consortium. The majority of subjects (n=264) received horse anti-thymocyte globulin (hATG) plus cyclosporine (CyA) with a median 61 months follow up. Following hATG/CyA, 71.2% (95%CI: 65.3,76.6) achieved an objective response. In contrast to adult studies, the quality of response achieved in pediatric patients was high, with 59.8% (95%CI: 53.7,65.8) complete response and 68.2% (95%CI: 62.2,73.8) achieving at least a very good partial response with a platelet count ≥50×109L. At five years post-hATG/CyA, overall survival was 93% (95%CI: 89,96), but event-free survival without subsequent treatment was only 64% (95%CI: 57,69) without a plateau. Twelve of 171 evaluable patients (7%) acquired clonal abnormalities after diagnosis after a median 25.2 months (range: 4.3-71 months) post treatment. Myelodysplastic syndrome or leukemia developed in 6 of 314 (1.9%). For relapsed/refractory disease, treatment with a hematopoietic stem cell transplant had a superior event-free survival compared to second immunosuppressive therapy treatment in a multivariate analysis (HR=0.19, 95%CI: 0.08,0.47; P=0.0003). This study highlights the need for improved therapies to achieve sustained high-quality remission for children with severe aplastic anemia.
| S-EPMC6886407 | biostudies-literature
Project description:Acquired aplastic anemia (AA) is the typical bone marrow failure syndrome characterized by an empty bone marrow; an immune-mediated pathophysiology has been demonstrated by experimental works as well as by clinical observations. Immunusuppressive therapy (IST) is a key treatment strategy for aplastic anemia; since 20 years the standard IST for AA patients has been anti-thymocyte globuline (ATG) plus cyclosporine A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after IST remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. Here we review the state of the art of IST for AA in 2010, focusing on possible strategies to improve current treatments. We also discuss very recent data which question the equality of different ATG preparations, leading to a possible reconsideration of the current standards of care for AA patients.
| S-EPMC3206528 | biostudies-literature
Project description: Not available
| S-EPMC4420224 | biostudies-literature
Project description:Acquired aplastic anemia (aAA) is an acquired deficiency of early hematopoietic cells, characterized by inadequate blood production, and a predisposition to myelodysplastic syndrome (MDS) and leukemia. Although its exact pathogenesis is unknown, aAA is thought to be driven by Human Leukocyte Antigen (HLA)-restricted T cell immunity, with earlier studies favoring HLA class II-mediated pathways. Using whole exome sequencing (WES), we recently identified two aAA patients with somatic mutations in HLA class I genes. We hypothesized that HLA class I mutations are pathognomonic for autoimmunity in aAA, but were previously underappreciated because the Major Histocompatibility Complex (MHC) region is notoriously difficult to analyze by WES. Using a combination of targeted deep sequencing of HLA class I genes and single nucleotide polymorphism array (SNP-A) genotyping we screened 66 aAA patients for somatic HLA class I loss. We found somatic HLA loss in eleven patients (17%), with thirteen loss-of-function mutations in HLA-A*33:03, HLA-A*68:01, HLA-B*14:02 and HLA-B*40:02 alleles. Three patients had more than one mutation targeting the same HLA allele. Interestingly, HLA-B*14:02 and HLA-B*40:02 were significantly overrepresented in aAA patients, compared to ethnicity-matched controls. Patients who inherited the targeted HLA alleles, regardless of HLA mutation status, had a more severe disease course with more frequent clonal complications as assessed by WES, SNP-A, and metaphase cytogenetics, and more frequent secondary MDS. The finding of recurrent HLA class I mutations provides compelling evidence for a predominant HLA class I-driven autoimmunity in aAA, and establishes a novel link between aAA patients' immunogenetics and clonal evolution.
| S-EPMC5621748 | biostudies-literature
Project description:Perforin is a cytolytic protein expressed mainly in activated cytotoxic lymphocytes and natural killer cells. Inherited perforin mutations account for 20% to 40% of familial hemophagocytic lymphohistiocytosis, a fatal disease of early childhood characterized by the absence of functional perforin. Aplastic anemia, the paradigm of immune-mediated bone marrow failure syndromes, is characterized by hematopoietic stem cell destruction by activated T cells and Th1 cytokines. We examined whether mutations in the perforin gene occurred in acquired aplastic anemia. Three nonsynonymous PRF1 mutations among 5 unrelated patients were observed. Four of 5 patients with the mutations showed some hemophagocytosis in the bone marrow at diagnosis. Perforin protein levels in these patients were very low or absent, and perforin granules were completely absent. Natural killer (NK) cell cytotoxicity from these patients was significantly decreased. Our data suggest that PRF1 genetic alterations help explain the aberrant proliferation and activation of cytotoxic T cells and may represent genetic risk factors for bone marrow failure.
| S-EPMC1890825 | biostudies-literature
Project description:Shwachman-Diamond syndrome (SDS; OMIM 260400), an inherited bone marrow failure syndrome, is caused by mutations in both alleles of the SBDS gene, which encodes a protein of unknown function. Here we report heterozygosity for the 258 + 2 T>C SBDS gene mutation previously identified in SDS patients in 4 of 91 patients with apparently acquired aplastic anemia (AA) but not in 276 ethnically matched controls (Fisher exact test, P < .004). Affected patients were young and had a poor outcome; they had reduced SBDS expression but no evidence of the pancreatic exocrine failure or skeletal abnormalities typical of SDS. Length of telomeres in granulocytes of SBDS heterozygous patients was short for their age, and in SDS patients with both SBDS alleles affected further analyzed, granulocytes' telomeres were even shorter, correlating in length with SBDS expression. Higher heterogeneity in telomere length also was observed in SDS patients. Telomerase activity of SBDS-deficient patients' lymphocytes was comparable with controls, and no physical interaction between SBDS protein and telomerase complex components (TERT or TERC) was established. We propose that heterozygosity for the 258 + 2 T>C SBDS mutation predisposes to AA by accelerating telomere shortening of leukocytes via a telomerase-independent mechanism.
| S-EPMC1939897 | biostudies-literature