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Mutations in the erythropoietin receptor gene are not a common cause of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is an inherited pure red blood cell aplasia that often requires lifelong transfusional support. The origin of the imperfect erythrogenesis is not known. The existence of more than one molecular basis for DBA is indicated by its different modes of inheritance and widely variable clinical phenotypes. Several erythroid growth factors have been thought to have a role in the pathogenesis of DBA. However, there is neither molecular nor clinical evidence for the involvement of stem cell factor or interleukin-3. The observation of elevated erythropoietin (EPO) concentrations and an impaired in vivo and in vitro response to pharmacologic doses of recombinant human EPO has suggested a defective EPO function in the pathogenesis of DBA. We have investigated the possible involvement of the EPO receptor (EPO-R) gene in 23 patients by screening its coding sequence for mutations using single-strand conformation polymorphism (SSCP). A Southern blot and hybridization with an EPO-R probe was also performed on DNA from seven patients. No causal mutations were identified. The absence of concordant segregation of the disease with the EPO-R gene in two informative families ruled out its role in their DBA children. These findings demonstrate that DBA is not commonly associated with EPO-R gene mutations.

Base Sequence↗

Shwachman-Diamond syndrome: the clinical imitator of cystic fibrosis.

In this case we report the autopsy findings of a four-month-old boy with the diagnosis of Shwachman-Diamond syndrome. The clinical and pathologic findings are discussed with emphasis on the differential diagnosis of cystic fibrosis and a brief review of current literature.

Bone Marrow Examination↗

Diamond-Blackfan anemia: a congenital defect in erythropoiesis.

Diamond-Blackfan anemia (DBA) is a congenital pure red blood cell aplasia diagnosed in the first year of life. Familiarity is apparent in 10% of patients, with all other cases being sporadic. Physical abnormalities are present in at least one third of patients, pointing to a defect in early embryo development. The main clinical sign is profound isolated anemia, with normal numbers and functioning of the other hemopoietic cells. Reticulocyte counts are very low. Bone marrow reflects defective erythropoiesis, showing a very low number of erythropoietic precursors and a reduction of BFU-E progenitor cells. Proliferation and differentiation of the other lineages are normal. The very high erythropoietin (EPO) levels are usually not proportionate to the level of anemia and reflect relative EPO insensitivity, which is also apparent in vitro. Conversely, erythroid progenitors from DBA patients also show a defective or incomplete response to other erythropoietic growth factors, such as IL-3 or IL-6. A significant response has been observed in vitro to stem cell factor in many, but not all patients. Many patients respond clinically to corticosteroids and some develop hematologic remissions, both after corticosteroids and spontaneously. Patients who do not respond to corticosteroids and those who have to discontinue treatment because of side effects must rely on chronic transfusion and are thus exposed to all its complications. Bone marrow transplantation has been performed in some individuals, usually with a successful outcome. This suggests a normal marrow microenvironment and rules out the hypothesis of defective stromal cell function. The variable clinical and biological patterns may be the expression of multiple etiologies or represent variable expressivity of a single genetic defect. Only identification of the responsible gene(s) will solve this question. Growth factors exerting an effect on erythropoiesis (and relative receptors) or transacting proteins which regulate their expression are likely candidates in the hunt for a causal gene.

Animals↗

Gardner-Diamond's syndrome in a man.

Gardner-Diamond's syndrome, or autoerythrocyte sensitization, is a disorder of spontaneous, painful ecchymoses whose pathogenesis is unresolved. The role of psychopathologic factors in this entity has been emphasized in previous reports. The patient in this study had a classical history and characteristic clinical features and is, to my knowledge, the first man described with this disorder.

Adult↗

Diamond-Blackfan anemia: expansion of erythroid progenitors in vitro by IL-9, but exclusion of a significant pathogenetic role for the IL-9 gene and the hematopoietic gene cluster on chromosome 5q.

Diamond-Blackfan anemia (DBA) is a congenital pure red blood cell aplasia that often requires lifelong transfusional therapy. Autosomal dominant and recessive inheritance have both been reported, suggesting genetic heterogeneity, but most cases occur sporadically. The origin of impaired erythropoiesis is unknown. Several erythroid growth factors have been thought to have a role in the pathogenesis of DBA. However, there is neither molecular nor clinical evidence for the involvement of erythropoietin (EPO), its receptor, stem cell factor (SCF), or interleukin (IL)-3, even if the addition of SCF to IL-3 and EPO does significantly increase the growth of erythroid progenitors in in vitro cultures in most patients. In this work we evaluated the possible role of another early-acting erythroid growth factor, IL-9. We found that the addition of IL-9 to SCF, IL-3, and EPO further increases burst-forming unit-erythroid growth in in vitro cultures of those DBA patients who responded to SCF. To investigate the role of the IL-9 gene, we evaluated its segregation in 22 families with members who have DBA by using a polymorphic microsatellite located within its intron 4. Lod score analysis ruled out any statistically significant involvement of the IL-9 gene in the pathogenesis of DBA. Moreover, linkage analysis with 11 highly polymorphic markers spanning 5q31.1-q33.2 excluded this region, which is included in the major cluster of genes active in hematopoiesis of the human genome.

Adolescent↗

Elevation of the serum Fas ligand in patients with hemophagocytic syndrome and Diamond-Blackfan anemia.

Fas ligand (FasL) is a membrane protein that is expressed in activated T cells and natural killer cells. FasL binds to Fas on target cells and induces apoptosis. There exists a soluble form of FasL (sFasL), and sFasL also induces apoptosis of Fas-bearing cells. The serum sFasL concentrations were reported to be elevated in patients with large granular lymphocytic leukemia and natural killer cell lymphoma. In this study, we have measured serum sFasL concentrations in other hematological disorders, including severe aplastic anemia (SAA), hemophagocytic lymphohistiocytosis (HLH), and Diamond-Blackfan anemia (DBA). The serum sFasL concentration of age-matched healthy controls was 0.16 +/- 0.11 ng/mL (mean +/- SD, n = 22). The serum sFasL levels in the patients with HLH and DBA were 3.75 +/- 3.82 (n = 19; P < .0001, HLH v control) and 2.76 +/- 2.43 ng/mL (n = 6; P = .012, DBA v control), respectively. Serum interferon-gamma concentration was elevated in the patients with HLH (1.61 +/- 2.62 ng/mL) but not in those with DBA (below the detectable level). These results suggest that the Fas-FasL system plays a role, at least in part, in the pathophysiology of HLH and DBA.

Adolescent↗

High adenosine deaminase level among healthy probands of Diamond Blackfan anemia (DBA) cosegregates with the DBA gene region on chromosome 19q13. The DBA Working Group of Société d'Immunologie Pédiatrique (SHIP).

Phenotypic characterization of Diamond Blackfan Anemia (DBA) patients and their relatives was performed in 54 families. Complete blood count, fetal hemoglobin level, erythrocyte i antigen expression, and erythrocyte adenosine deaminase (eADA) activities were quantitated in patients and relatives. eADA was elevated in 28 of 34 transfusion-independent DBA patients, whereas persistence of erythrocyte i antigen was noticed in only 10 of 20 DBA patients. High eADA activities were also found in 14 of 149 healthy family members, allowing us to identify an isolated high eADA phenotype in these families. In contrast, increase in erythrocyte i antigen expression, elevated fetal hemoglobin levels, and macrocytosis were much less frequently noted in nonaffected members of the DBA families studied. Importantly, isolated high eADA phenotype was found to be significantly associated with genetic markers on chromosome 19 that segregate with the DBA phenotype. Isolated high eADA phenotype thus seems to reflect a silent phenotype of DBA in affected families. These findings suggest that elevated eADA activity in unaffected individuals needs to be taken into account during genetic assessment of DBA families and could be used for accurate assessment of mode of inheritance.

Adenosine Deaminase↗

[Long term evolution in Blackfan-Diamond hypoplastic anemia (author's transl)].

Six cases of Blackfan-Diamond hypoplastic anemia are reported. Five were initiated within six months of life. All cases showed intense anemia, severe reticulopenia and hypersideremia. Two of them had associated malformations. Treatment was established with Dexametasone at high doses, followed by a maintenance treatment at lower doses. A partial response was obtained in all cases. Treatment with deforroxiamine was used in order to paliate hemosiderosis. Two cases developped microangiopathic hemolitic anemia; relations with primary disease could not be determined.

Abnormalities, Multiple↗