Recurrent 6pLOH Is the Most Common Somatic Lesion in Refractory Cytopenia of Childhood and Occurs Very Infrequently in Severe Aplastic Anemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 644-644 ◽  
Author(s):  
Marcin W Wlodarski ◽  
Shinsuke Hirabayashi ◽  
Brigitte Strahm ◽  
Sandra Urbaniak ◽  
Brigitte Schlegelberger ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
Telomere Length ◽  
Copy Number ◽  
Bone Marrow Failure ◽  
Good Prognosis ◽  
Severe Aplastic Anemia ◽  
Diamond Blackfan Anemia ◽  
Immune Mediated ◽  
Somatic Aberrations

Abstract Abstract 644 Refractory cytopenia of the childhood (RCC) and severe aplastic anemia (SAA) are the most common causes of acquired hypoplastic bone marrow failure (BMF) in children. Although predisposing genetic factors and inciting immunological events had been implicated, little is known about the molecular origins of these conditions. Whole-genome scanning using single nucleotide polymorphism arrays (SNP-A) can complement standard cytogenetics in terms of the detection of submicrocopic aberrations and regions with copy number neutral loss of heterozygosity (CN-LOH). Here we present the results of an analysis of 181 children with bone marrow failure: MDS, n=106; SAA, n=41; and for hematological control, 34 patients with Diamond Blackfan anemia (DBA). To enrich for the myeloid lineage, we used granulocytes from bone marrow as source for DNA. We employed Affymetrix 6.0 arrays and used CNAG v3.3 and Genotyping Console v4.0 platforms for data analysis. To identify somatic aberrations that might have been missed by standard metaphase cytogenetics (MC), we initially looked at cases with abnormal MC, presenting as RCC or advanced MDS (n=25, median age 12.4 years). While SNP-A generally confirmed the cytogenetic lesions identified by MC, no novel recurrent somatic aberrations with pathogenic character were discovered. In the next step we focused on the analysis of RCC patients with normal karyotype (N=81, median age 10.2 years). In one case a small monosomy 7 clone was identified using SNP-A, that has been missed by standard MC. Most strikingly, 11 patients (14%) carried clones with a terminal CN-LOH of the short arm of chromosome 6 (6pLOH), with a length of 30–42Mb and various clonal size. The somatic myeloid origin was confirmed by the analysis of CD4+/CD8+ sorted T-cells in several cases. The 6pLOH lesion encompasses the HLA gene cluster leading to the loss of one HLA haplotype, has previously been reported in adults with SAA diagnosed in USA and Japan (Afable/Wlodarski, and Katagiri 2011), and was generally associated with a good prognosis. Regarding treatment modalities in RCC patients, the 6pLOH clone was overrepresented in the watch and wait (W&W) cohort: 10/55 (18%) of W&W cases carried this clone, as compared to 1/26 (4%) patient who received therapy within 6 months from diagnosis. Out of the 10 W&W patients with 6pLOH clone, only two required later therapeutic interventions (stem cell transplantation) due to progressive cytopenia at 10 and 11 months after diagnosis. The remaining 8/10 patients are still under W&W strategy with a median FUP of 6.6 (1.6.-12.2) years. In summary, all 11 RCC 6pLOH patients are alive with a median FUP of 6.6 years without disease progression. Interestingly, the 6pLOH clone survives over a long period of time, as confirmed in 2 patients in different bone marrow samples obtained 7 years apart. To answer the question if the persistence of the 6pLOH clones has an effect on telomere maintenance in the hematopoietic cell compartment, we measured telomere length using a quantitative PCR-based approach. All 11 RCC cases with 6pLOH studied had normal telomere length as compared to age-matched controls. Since the immune-mediated attack is the main operating mechanism of BMF in SAA, we next asked whether the 6pLOH clone can also arise in the bone marrow of children with SAA. We SNP-A genotyped a cohort of 41 SAA patients (median age 10.4 years) including 5 hepatitis-associated SAA (HSAA) cases. While no genomic copy number alterations were found, the somatic 6pLOH clone was discovered in only one HSAA patient, in whom the SAA developed 6 months after onset of hepatitis. When compared to the SAA patients, the 6pLOH clone is significantly more frequent in the RCC W&W cohort (P <0.04). Finally, to compare the results to a “non-immune-mediated” BMF, we analyzed 34 children with Diamond Blackfan anemia in whom no 6pLOH clone or other somatic defects were identified. In summary, 6pLOH is the most common somatic lesion found in the myeloid compartment in RCC patients and correlates with a very good prognosis. The absence of 6pLOH in children with SAA with no other associated pathologies supports the concept that RCC and SAA are two distinct entities in children. Disclosures: No relevant conflicts of interest to declare.

scholarly journals PKM2 Is Required to Activate Myeloid Dendritic Cells from Patients with Severe Aplastic Anemia

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Chunyan Liu ◽  
Mengying Zheng ◽  
Ting Wang ◽  
Huijuan Jiang ◽  
Rong Fu ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Aplastic Anemia ◽  
Immune Status ◽  
Bone Marrow Failure ◽  
Severe Aplastic Anemia ◽  
Myeloid Dendritic Cells ◽  
Protein Levels ◽  
Immune Mediated ◽  
Normal Controls

Severe aplastic anemia (SAA) is an autoimmune disease in which bone marrow failure is mediated by activated myeloid dendritic cells (mDCs) and T lymphocytes. Recent research has identified a strong immunomodulatory effect of pyruvate kinase M2 (PKM2) on dendritic cells in immune-mediated diseases. In this study, we aimed to explore the role of PKM2 in the activation of mDCs in SAA. We observed conspicuously higher levels of PKM2 in mDCs from SAA patients compared to normal controls at both the gene and protein levels. Concurrently, we unexpectedly discovered that after the mDC-specific downregulation of PKM2, mDCs from patients with SAA exhibited weakened phagocytic activity and significantly decreased and shortened dendrites relative to their counterparts from normal controls. The expression levels of the costimulatory molecules CD86 and CD80 were also reduced on mDCs. Our results also suggested that PKM2 knockdown in mDCs reduced the abilities of these cells to promote the activation of CD8+ T cells (CTLs), leading to the decreased secretion of cytotoxic factors by the latter cell type. These findings demonstrate that mDC activation requires an elevated intrinsic PKM2 level and that PKM2 improves the immune status of patients with SAA by enhancing the functions of mDCs and, consequently, CTLs.

scholarly journals Aplastic anemia: immunosuppressive therapy in 2010

2011 ◽  
Vol 3 (2s) ◽  
pp. 7 ◽  
Author(s):  
Antonio M. Risitano ◽  
Fabiana Perna
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
State Of The Art ◽  
Bone Marrow Failure ◽  
Standards Of Care ◽  
Bone Marrow Failure Syndrome ◽  
Clinical Observations ◽  
Immune Mediated ◽  
Experimental Works ◽  
Current Standards

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.

scholarly journals Severe Aplastic Anemia following Acute Hepatitis from Toxic Liver Injury: Literature Review and Case Report of a Successful Outcome

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Kamran Qureshi ◽  
Usman Sarwar ◽  
Hicham Khallafi
Keyword(s):  
Bone Marrow ◽  
Liver Injury ◽  
Acute Hepatitis ◽  
Aplastic Anemia ◽  
Viral Infections ◽  
Anabolic Steroids ◽  
Bone Marrow Failure ◽  
Young Male ◽  
Severe Aplastic Anemia ◽  
Successful Outcome

Hepatitis associated aplastic anemia (HAAA) is a rare syndrome in which severe aplastic anemia (SAA) complicates the recovery of acute hepatitis (AH). HAAA is described to occur with AH caused by viral infections and also with idiopathic cases of AH and no clear etiology of liver injury. Clinically, AH can be mild to fulminant and transient to persistent and precedes the onset SAA. It is assumed that immunologic dysregulation following AH leads to the development of SAA. Several observations have been made to elucidate the immune mediated injury mechanisms, ensuing from liver injury and progressing to trigger bone marrow failure with the involvement of activated lymphocytes and severe T-cell imbalance. HAAA has a very poor outcome and often requires bone marrow transplant (BMT). The findings of immune related myeloid injury implied the use of immunosuppressive therapy (IST) and led to improved survival from HAAA. We report a case of young male who presented with AH resulting from the intake of muscle building protein supplements and anabolic steroids. The liver injury slowly resolved with supportive care and after 4 months of attack of AH, he developed SAA. He was treated with IST with successful outcome without the need for a BMT.

Erythrocytosis after Allogeneic Bone Marrow Transplantation in the Patients with Severe Aplastic Anemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5327-5327
Author(s):  
Soo-Jeong Park ◽  
Chi-Wha Han
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Aplastic Anemia ◽  
Bone Marrow Failure ◽  
Allogeneic Bone Marrow Transplantation ◽  
Severe Aplastic Anemia ◽  
Allogeneic Bone ◽  
Laboratory Findings ◽  
Normal Ranges ◽  
Serum Erythropoietin Level

Abstract Severe aplastic anemia (sAA) is a bone marrow failure disorder which is mostly a consequence of immunologically mediated stem cell destruction. Stem cell transplantation (SCT) from a histocompatible sibling is a treatment of choice for this disease but major obstacles in success of allogeneic SCT include graft-versus-host disease (GVHD), graft rejection and treatment related toxicities. We describe two cases of post-transplant erythrocytosis in severe aplastic anemia. About 5 years later, following HLA-matched sibling transplantation, the patients (45-year-old male and 43-year-old male) developed a sustained increase in hemoglobin (>17 g/dL) and hematocrit (> 50%), an increase in the frequency of headache, and new onset of dizziness and malaise. Laboratory findings demonstrated normal ranges of other blood components and serum erythropoietin level, and they did not have smoking or other drugs. Also, they did not have a hepatosplenomegaly or other organ diseases. We initiated a therapeutic phlebotomy program (400 ml q 2–4 weeks and then q 2–3 months for 5 years) in order to lower the hematocrit to available values (Hb < 14.5 g/dL), and to induce iron deficiency (Fig 1). Repeated phlebotomy resulted in a decrease in symptoms and a total volume of blood venesection is about 9,200 – 11,200 ml so far. Figure 1. Hemoglobin change after bone marrow transplantations. Figure 1. Hemoglobin change after bone marrow transplantations.

Age-Adjusted Telomere Length Is Not Associated with Variation in Hematological Parameters in Ageing Women

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3102-3102
Author(s):  
Isabelle Fleury ◽  
Sylvie Provost ◽  
Claude Belisle ◽  
Lambert Busque
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Transplantation ◽  
Telomere Length ◽  
Marrow Transplantation ◽  
Copy Number ◽  
Bone Marrow Failure ◽  
Telomere Maintenance ◽  
Hematological Parameter ◽  
Allogeneic Bone ◽  
Potential Biomarker

Abstract Background. Telomeres play a crucial role in maintaining physical integrity of chromosomes. In the absence of telomerase, telomere length (TL) shortens with each cell division up to a critical threshold where cellular senescence occurs. TL is inversely correlated with age, is longer in women than in men, and demonstrates a strong heritability. Normal blood counts are maintained through out life by an extraordinary number of cell divisions rendering telomere maintenance primordial to prevent stem cell exhaustion. In fact, some cases of bone marrow failure syndromes, such as aplastic anemia and dyskeratosis congenital, have been linked to mutation in the telomerase gene; and stressed hematopoiesis, such at it occurs during the first year following allogeneic bone marrow transplantation induces TL shortening. We hypothesized that individuals with shorter TL may have lower blood counts and a decreased bone marrow reserve. The evaluation of TL as a potential biomarker of ageing hematopoiesis is important in the context of bone marrow transplantation performed with increasingly old donors. Methods. We measured TL in 1583 women, predominantly aged over 60, all originating from 288 French-Canadian families using a real-time quantitative PCR method that measures the number of telomere repeats relatively to the copy number of a single copy number gene. Telomeres were adjusted for age. Pearson or Spearman correlations were used to determine association between age-adjusted TL (aTL) and hematological parameter according to, respectively, whether or not a normal distribution was observed for these data. A Bonferroni correction was further applied to set the statistical significance threshold. Results. aTL varied significantly between individuals of the cohort, but no correlation was detected with hemoglobin levels (−0,001; p=0,978), mean corpuscular volume (−0,031; p=0,403); leucocytes (0,055; p=0,139); neutrophils (0,078; p=0,036), monocytes, (0,059; p=0,113), eosinophils (−0,032; p=0,394) and platelets (0,030; p=0,428) counts. Conclusion. Based on our analysis, TL do not predict blood cells counts in ageing women and may not be a useful biomarker for donor selection. This could also suggest that there is a threshold beyond which TL has an effect on hematopoiesis and that point was not reached in our cohort.

Bone Marrow Histology in Patients with Paroxysmal Nocturnal Hemoglobinuria.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4215-4215
Author(s):  
Sandra van Bijnen ◽  
Konnie Hebeda ◽  
Petra Muus
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Aplastic Anemia ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Plasma Cells ◽  
Bone Marrow Failure ◽  
Clone Size ◽  
Immune Mediated ◽  
Lymphoid Nodules ◽  
Pnh Clone

Abstract Abstract 4215 Introduction Paroxysmal Nocturnal Hemoglobinuria (PNH) is a disease of the hematopoietic stem cell (HSC) resulting in a clone of hematopoietic cells deficient in glycosyl phosphatidyl inositol anchored proteins. The clinical spectrum of PNH is highly variable with classical hemolytic PNH at one end, and PNH in association with aplastic anemia (AA/PNH) or other bone marrow failure states at the other end. It is still largely unknown what is causing these highly variable clinical presentations. Immune-mediated marrow failure has been suggested to contribute to the development of a PNH clone by selective damage to normal HSC. However, in classic PNH patients with no or only mild cytopenias, a role for immune mediated marrow failure is less obvious. No series of trephine biopsies has been previously documented of patients with PNH and AA/PNH to investigate the similarities and differences in these patients. Methods We have reviewed a series of trephine biopsies of 41 PNH patients at the time the PNH clone was first detected. The histology was compared of 27 patients with aplastic anemia and a PNH clone was compared to that of 14 patients with classic PNH. Age related cellularity, the ratio between myeloid and erythroid cells (ME ratio), and the presence of inflammatory cells (mast cells, lymphoid nodules and plasma cells) were evaluated. The relation with clinical and other laboratory parameters of PNH was established. Results Classic PNH patients showed a normal or hypercellular marrow in 79% of patients, whereas all AA/PNH patients showed a hypocellular marrow. Interestingly, a decreased myelopoiesis was observed not only in AA/PNH patients but also in 93% of classic PNH patients, despite normal absolute neutrophil counts (ANC ≥ 1,5 × 109/l) in 79% of these patients. The number of megakaryocytes was decreased in 29% of classic PNH patients although thrombocytopenia (< 150 × 109/l) was only present in 14% of the patients. Median PNH granulocyte clone size was 70% (range 8-95%) in classic PNH patients, whereas in AA/PNH patients this was only 10% (range 0.5-90%). PNH clones below 5% were exclusively detected in the AA/PNH group. Clinical or laboratory evidence of hemolysis was present in all classical PNH patients and in 52% of AA/PNH patients and correlated with PNH granulocyte clone size. Bone marrow iron stores were decreased in 71% of classic PNH patients. In contrast, increased iron stores were present in 63% of AA/PNH patients, probably reflecting their transfusion history. AA/PNH patients showed increased plasma cells in 15% of patients and lymphoid nodules in 37%, versus 0% and 11% in classic PNH. Increased mast cells (>2/high power field) were three times more frequent in AA/PNH (67%) than in PNH (21%). Conclusion Classic PNH patients were characterized by a more cellular bone marrow, increased erythropoiesis, larger PNH clones and clinically by less pronounced or absent peripheral cytopenias and more overt hemolysis. Decreased myelopoiesis and/or megakaryopoiesis was observed in both AA/PNH and classic PNH patients, even in the presence of normal peripheral blood counts, suggesting a role for bone marrow failure in classic PNH as well. More prominent inflammatory infiltrates were observed in AA/PNH patients compared to classical PNH patients. Disclosures: No relevant conflicts of interest to declare.

scholarly journals A multicenter trial of antithymocyte globulin in aplastic anemia and related diseases

Blood ◽  
1988 ◽  
Vol 72 (6) ◽  
pp. 1861-1869
Author(s):  
N Young ◽  
P Griffith ◽  
E Brittain ◽  
G Elfenbein ◽  
F Gardner ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
Antithymocyte Globulin ◽  
Bone Marrow Failure ◽  
Multicenter Trial ◽  
Severe Aplastic Anemia ◽  
Transfusion Independence ◽  
Group I ◽  
Significant Difference ◽  
To Receive

One hundred fifty patients with bone marrow failure were treated in three groups with antithymocyte globulin (ATG; Upjohn, Kalamazoo, MI) in a multicenter trial. Patients were assessed at 3, 6, and 12 months after initiation of treatment by three criteria: transfusion independence, clinical improvement, and blood counts. Group I consisted of 77 patients with acute severe aplastic anemia, randomized to receive either ten or 28 days of ATG. There was no significant difference between the two arms of this protocol: 47% of all patients were clinically improved and 31% were transfusion independent at 3 months. Of the severely affected patients, 27% died before 3 months; most deaths occurred early in treatment. Factors associated with survival in severely affected patients included male sex, age less than 40 years, absolute neutrophil count greater than 200/microL, and idiopathic etiology. Neutrophil counts generally increased by 8 weeks after treatment, but patients continued to show improvement to 1 year posttreatment. In Group II, 44 patients with moderate or chronic severe aplastic anemia were randomized to receive either ten days of ATG or 3 months of high-dose nandrolone decanoate. No patient initially treated with androgens recovered, but 28% of ATG-treated cases achieved transfusion independence at 3 months. Group III consisted of patients with a variety of bone marrow failure syndromes. Patients with pancytopenia and cellular bone marrow showed response rates similar to those of patients with chronic or moderate aplastic anemia.

Telomerase Gene Mutation Screening and Telomere Length Detection in Chinese Patients with Bone Marrow Failure Syndrome.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1047-1047
Author(s):  
Bing Han ◽  
Bo Liu ◽  
Yongqiang Zhao
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
Small Group ◽  
Telomere Length ◽  
Gene Mutation ◽  
Bone Marrow Failure ◽  
Chinese Patients ◽  
Chinese People ◽  
Bone Marrow Failure Syndrome ◽  
Tert Mutation

Abstract Background Acquired bone marrow failure syndrome (BMF) is a group of diseases include aplastic anemia(AA), melodysplastic syndrome (MDS) and paraoxymal nocturnal hemoglobinuria (PNH). Some BMF patients have short telomeres in their peripheral nucleated cells. The length of telomere is maintained by a group of enzymes called telomerase complex. The core components of this complex are a RNA template and a reverse transcriptase, called TERC and TERT, respectively. Recently several studies in the west and Japan have disclosed the presence of telomerase complex gene mutation in a small group of patients with acquired bone marrow failure. They speculated that this small group of patients might represent a subset of cryptogenic Dyskeratosis Congenita (DKC), in which the premature exhaustion of hematopoietic reservoir is caused by mutations in the telomerase gene. This group of patients, though very small in number, would benefit from early bone marrow transplantation instead of traditional immunosuppressive therapy. The incidence of aplastic anemia in Chinese people is relatively high compared with that in the western country. But there has so far been no study in China about the incidence of telomerase gene mutation in acquired bone marrow failure and its relationship with telomere length. Objectives To study the incidence of telomerase gene (namely TERC and TERT ) mutation in Chinese patients with acquired bone marrow failure and explore its relationship with telomere shortening. Methods Blood samples from 90 patients with AA, MDS, and PNH in northern China were collected and performed TERC and TERT mutation analysis. Telomere length was measured by Southern blotting and compared with their normal counterparts. Results 2 TERC mutations (n37 A→G, reported previously ; n66G→C) and 2 TERT mutations (n1870G→T (E/*); n1780G→T (S/I) ) were identified in 90 BMF patients. Among them, 3 mutations are reported first time. 1 patient with TERT mutation, however, was finally diagnosed as DKC instead of acquired AA, making the incidence of telomerase gene mutation in Chinese people with acquired bone marrow failure 3.4%, similar to that of the western people. Southern Blot analysis showed the small group of patients carrying TERC and TERT mutations has very short telomeres, compared with normal controls and with their aplastic counterparts. Conclusions The incidence of telomerase gene mutation in Chinese people with acquired bone marrow failure is 3.4%, similar to that of the western people. This small group of patients has very short telomeres, it is thus clinically important to screen for this small group of patients.

Significance of Telomere Length Measurement in the Diagnosis of Dyskeratosis Congenita.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 836-836
Author(s):  
Hong-Yan Du ◽  
Elena Pumbo ◽  
Akiko Shimamura ◽  
Adrianna Vlachos ◽  
Jeffrey M. Lipton ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
Telomere Length ◽  
Bone Marrow Failure ◽  
Skin Pigmentation ◽  
Screening Method ◽  
Dyskeratosis Congenita ◽  
Telomere Maintenance ◽  
Healthy Controls ◽  
Mutation Carriers

Abstract Dyskeratosis congenita (DC) is a rare inherited bone marrow failure (BMF) syndrome. The classical features of DC include nail dystrophy, abnormal skin pigmentation, and mucosal leukoplakia. The diagnosis of DC can be difficult. Originally, the diagnosis was based on the presence of the classical mucocutaneous features. However, the identification of four genes responsible for DC (DKC1, TERC, TERT, and NOP10) showed that these mucocutaneous features are only present in a proportion of patients with DC. Additionally, screening for mutations in the affected genes is expensive and is negative in about 50% of patients with classical features of DC. The products of the genes mutated in DC are the components of the telomerase ribonucleoprotein complex, which is essential for telomere maintenance. Therefore it has been postulated that DC is a disease arising from excessive telomere shortening. Here we examined whether the measurement of telomeres could be used as a screening test to identify individuals with DC. For this purpose we examined telomere length in peripheral blood mononuclear cells from 169 patients who presented with bone marrow failure including 17 patients with DC, diagnosed by the presence of classical cutaneous features or the identification of mutations in DKC1, TERC or TERT, 28 patients with paroxysmal nocturnal hemoglobinuria, 25 patients with Diamond Blackfan anemia, 5 patients with Shwachman-Diamond syndrome, 8 patients with myelodysplastic syndrome, and 74 patients with aplastic anemia of unknown cause classified as idiopathic aplastic anemia. In addition we measured telomere length in 12 patients with idiopathic pulmonary fibrosis and in 45 individuals with a de novo deletion of chromosome 5p including the TERT gene. Their telomere lengths were compared with those of 202 age-matched healthy controls. Moreover, mutations were screened in the genes associated with DC. In cases where a mutation was identified, telomere length and mutations were also examined in all the family members. Our results show that all patients with DC and bone marrow failure have very short telomeres far below the first percentile of healthy controls. Not all mutation carriers, including some carriers of apparently dominant mutations, have very short telomeres. What is more, very short telomeres could be found in healthy individuals in these families, some of whom were not mutation carriers. These findings indicate that in patients with BMF the measurement of telomere length is a sensitive screening method for DC, whether very short telomeres in this setting are also specific for DC remains to be determined. However, in contrast to a previous study, we find that telomere length does not always identify mutation carriers in the families of DC.

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