The morphological diagnosis of congenital dyserythropoietic anemia: Results of a quantitative analysis of peripheral blood and bone marrow cells

Haematologica (Impact Factor: 5.81). 06/2010; 95(6):1034-6. DOI: 10.3324/haematol.2009.014563
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    • "The clinical picture is characterized by mild to moderate anemia associated with jaundice, splenomegaly, and iron overload [3,4]. In clinical practice, evidence of CDAII is primarily based on bone marrow examination [5,6]. Confirmation of diagnosis is based on at least one of the following biochemical tests, including: a positive acid serum lysis test with ABO-compatible sera; band 3 protein glycosylation defects evidenced by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE); a discontinuous double membrane in mature erythroblasts (visible by electron microscopy), and the presence of endoplasmic reticulum (ER)-specific proteins [5,7-9]. "
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    ABSTRACT: Congenital dyserythropoietic anemia type II (CDAII), the most common form of CDA, is an autosomal recessive condition. CDAII diagnosis is based on invasive, expensive, and time consuming tests that are available only in specialized laboratories. The recent identification of SEC23B mutations as the cause of CDAII opens new possibilities for the molecular diagnosis of the disease. The aim of this study was to characterize molecular genomic SEC23B defects in 16 unrelated patients affected by CDAII and correlate the identified genetic alterations with SEC23B transcript and protein levels in erythroid precursors. SEC23B was sequenced in 16 patients, their relatives and 100 control participants. SEC23B transcript level were studied by quantitative PCR (qPCR) in peripheral erythroid precursors and lymphocytes from the patients and healthy control participants. Sec23B protein content was analyzed by immunoblotting in samples of erythroblast cells from CDAII patients and healthy controls. All of the investigated cases carried SEC23B mutations on both alleles, with the exception of two patients in which a single heterozygous mutation was found. We identified 15 different SEC23B mutations, of which four represent novel mutations: p.Gln214Stop, p.Thr485Ala, p.Val637Gly, and p.Ser727Phe. The CDAII patients exhibited a 40-60% decrease of SEC23B mRNA levels in erythroid precursors when compared with the corresponding cell type from healthy participants. The largest decrease was observed in compound heterozygote patients with missense/nonsense mutations. In three patients, Sec23B protein levels were evaluated in erythroid precursors and found to be strictly correlated with the reduction observed at the transcript level. We also demonstrate that Sec23B mRNA expression levels in lymphocytes and erythroblasts are similar. In this study, we identified four novel SEC23B mutations associated with CDAII disease. We also demonstrate that the genetic alteration results in a significant decrease of SEC23B transcript in erythroid precursors. Similar down-regulation was observed in peripheral lymphocytes, suggesting that the use of these cells might be sufficient in the identification of Sec23B gene alterations. Finally, we demonstrate that decreased Sec23B protein levels in erythroid precursors correlate with down-regulation of the SEC23B mRNA transcript.
    Orphanet Journal of Rare Diseases 12/2011; 6(1):89. DOI:10.1186/1750-1172-6-89 · 3.36 Impact Factor
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    ABSTRACT: The congenital dyserythropoietic anemias (CDAs) are a group of rare hereditary disorders characterized by ineffective erythropoiesis and distinct morphologic abnormalities of the erythroblasts in the bone marrow. CDA type II (CDA II) is the most common subtype, with more than 300 cases reported in the literature. Patients often present with anemia, jaundice, and variable splenomegaly. Most cases of CDA II are diagnosed at a young age; some patients, however, may remain unrecognized until late adulthood. Unless CDA is considered in the differential diagnosis for anemia, adult patients are often subjected to extensive clinical work-up for many years prior to accurate diagnosis. Early recognition of CDA II is important to prevent end-organ damage secondary to iron overload, the most important complication of the disease. We report a case of CDA II diagnosed in a 48-year-old woman with a longstanding history of anemia of unknown etiology. KeywordsCongenital dyserythropoietic anemia type II (CDA II)-Hereditary erythroblastic multinuclearity with a positive acidified serum test (HEMPAS)-Anemia-Dyserythropoiesis-Ineffective erythropoiesis
    12/2010; 3(4):149-153. DOI:10.1007/s12308-010-0073-5
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    ABSTRACT: The congenital dyserythropoietic anemias (CDAs) are inherited red blood cell disorders whose hallmarks are ineffective erythropoiesis, hemolysis, and morphological abnormalities of erythroblasts in bone marrow. We have identified a missense mutation in KLF1 of patients with a hitherto unclassified CDA. KLF1 is an erythroid transcription factor, and extensive studies in mouse models have shown that it plays a critical role in the expression of globin genes, but also in the expression of a wide spectrum of genes potentially essential for erythropoiesis. The unique features of this CDA confirm the key role of KLF1 during human erythroid differentiation. Furthermore, we show that the mutation has a dominant-negative effect on KLF1 transcriptional activity and unexpectedly abolishes the expression of the water channel AQP1 and the adhesion molecule CD44. Thus, the study of this disease-causing mutation in KLF1 provides further insights into the roles of this transcription factor during erythropoiesis in humans.
    The American Journal of Human Genetics 11/2010; 87(5):721-7. DOI:10.1016/j.ajhg.2010.10.010 · 10.93 Impact Factor
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