Congenital Dyserythropoietic Anemia Type Research Articles

3′-Azidothymidine Potently Inhibits the Biosynthesis of Highly Branched N-Linked Oligosaccharides and Poly-N-acetyllactosamine Chains in Cells

3′-Azidothymidine Potently Inhibits the Biosynthesis of Highly Branched N-Linked Oligosaccharides and Poly-N-acetyllactosamine Chains in Cells

Diagnostik und Genetik der kongenitalen dyserythropoetischen Anämien (CDA)

The congenital dyserythropoietic anemias (CDA) are hereditary diseases characterized by a lifelong, mostly moderate anemia. CDA can be diagnosed already in early childhood. However, diagnosis is complicated due to poor knowledge of morphological criteria and the large number of differential diagnoses that have to be excluded. CDA type I is characterized by macrocytic anemia with megaloblastic changes in erythropoiesis and chromatin bridges between isolated erythroblasts. Type II shows a normocytic anemia with a positive acidified serum test and increased agglutination with anti-i. Erythroblasts can present with 2 or more nuclei. CDA type III presents with a macrocytic anemia and erythroblasts with up to 12 nuclei, the so called gigantoblasts. Some patients lack the typical morphological abnormalities of type I-III (variants or type IV). Besides light microscopic abnormalities, CDA type-specific changes in electron microscopy are described. The clinical picture of the patients vary between the different forms: signs of hemolysis and ineffective erythropoiesis such as icterus, splenomegaly and gall stones can be present. Most important is the tendency of a part of patients to have an increased iron absorption and iron storage. Patients with and without transfusion dependency are described. Supportive care such as iron chelation can be necessary in some patients. The CDA are inherited in an autosomal recessive manner; in type III an additional autosomal dominant variant exists. Recently, the determination of gene loci for type I, II and III was enabled by linkage analysis on different regions of chromosome 15 and 22. It is considered that CDA I and II are genetically heterogenic. Until now no gene has been identified in either type of CDA. In CDA type II, a glycosylation defect of erythrocyte membrane proteins is present. An international group plans to do further research. Therefore, identification and registration of patients in a registry is necessary. Patients' data and material would enable gene characterization. The results would allow an extended classification according to genotype and prediction of the course of the disease. Additionally, information on the regulation and control of normal and abnormal erythropoiesis could be obtained.

Congenital dyserythropoietic anemia type I presenting as persistent pulmonary hypertension of the newborn

Congenital dyserythropoietic anemia (CDA) is a rare group of inherited bone marrow disorders characterized by anemia with ineffective erythropoiesis. We report 3 siblings from a family known to have CDA type I who presented with persistent pulmonary hypertension of the newborn (PPHN). We suggest that the diagnosis of CDA type I should be considered in any neonate with PPHN and anemia.

Gilbert's syndrome accounts for the phenotypic variability of congenital dyserythropoietic anemia type II (CDA-II)

The molecular basis for the considerable variation of serum bilirubin levels and the incidence of gallstone formation in patients with congenital dyserythropoietic anemia (CDA) type II are unknown. We show that the combined effect of an increased bilirubin load caused by dyserythropoiesis in CDA II and decreased bilirubin conjugation caused by reduced expression of uridine diphosphate glucuronosyl transferase (UGT1A) would increase the risk of hyperbilirubinemia (P < .005) and gallstone formation (X2: P < .001). The rate of gallstone formation in patients with CDA II is 4.75-fold the rate of patients without Gilbert's syndrome, and gallstone diagnosis occurs at a younger age (P < 0.01). These findings should be considered during the follow-up of patients with CDA II.

Congenital dyserythropoietic anemias.

The congenital dyserythropoietic anemias (CDAs) are an uncommon and heterogeneous group of disorders characterized by markedly ineffective erythropoiesis and, usually, striking dysplastic changes in erythroblasts. Each of the three originally described forms, designated CDA types I to III, is defined by the presence of distinctive morphologic (including ultrastructural) abnormalities in erythroblasts. CDA type II is also characterized by a marked reduction in polylactosamine structures associated with the erythrocyte membrane glycoprotein, band 3 (detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis), and, usually, a positive result on the acidified serum lysis test. The course of CDA is often complicated by cholelithiasis. Even patients who have not had transfusions sometimes develop substantial iron overload. Recent studies have extended our knowledge on the clinical manifestations of CDA types I and III and have revealed the existence of forms of CDA distinct from types I to III. Information is now available on the chromosomal localization of the genes involved in CDA types I and II and in the Swedish cases of CDA type III. A few patients with CDA type I have been treated with interferon-alpha2, with a good response.

Determinants of iron status and bilirubin levels in congenital dyserythropoietic anaemia type I.

Seven untransfused patients with congenital dyserythropoietic anaemia type I were investigated to assess the determinants of both iron overload and serum bilirubin levels. The serum ferritin concentration was increased in all patients and non-transferrin-bound iron (NTBI) was increased in all but one patient. None of the patients showed the C282Y mutation in the hereditary haemochromatosis gene, HFE. One patient was homozygous for the H63D mutation in this gene. The data indicated that differences in the extent of iron overload were not mediated by co-inheritance of the C282Y mutation in the HFE gene but could largely be explained by differences in the severity of anaemia and ineffective erythropoiesis, and in the age of the patient. In one patient an unusually high plasma bilirubin level was associated with the variant A[TA]7TAA configuration in the TATA box of the uridine diphosphate glucuronosyltransferase (UGT-1A) gene promoter, the mutation found in most patients with mild Gilbert's syndrome.

Soluble transferrin receptor as a potential determinant of iron loading in congenital anaemias due to ineffective erythropoiesis.

Congenital anaemias due to ineffective erythropoiesis may be associated with excessive iron absorption and progressive iron loading. We investigated whether the soluble transferrin receptor (TfR) level was related to the degree of iron overload in 20 patients with thalassaemia intermedia, six patients with congenital dyserythropoietic anaemia type II (CDA II) and four patients with X-linked congenital sideroblastic anaemia (XLSA). All but two patients had increased serum ferritin levels (median 601 microgram/l, range 105-2855 microgram/l). Multiple regression analysis showed that 62% (P < 0.0001) of the variation in serum ferritin was explained by age and by changes in soluble TfR.

NO RESPONSE TO RECOMBINANT HUMAN ERYTHROPOIETIN THERAPY IN PATIENTS WITH CONGENITAL DYSERYTHROPOIETIC ANEMIA TYPE I

Congenital dyserythropoietic anemia (CDA) type I is a rare inherited bone marrow disorder characterized by moderate to severe macrocytic anemia with pathognomonic cytopathology of nucleated red blood cells. Previous studies have suggested that serum erythropoietin levels in affected patients are lower than expected for the degree of anemia. An earlier study demonstrated a substantial increase in the number of CFU-E in CDA type I pattern on addition of exogenous erythropoietin. The present study reports on the response to recombinant human erythropoietin in 8 patients with CDA type I. Eighteen weeks of treatment, starting at 300 IU/kg twice a week and gradually increasing to 500 IU/kg three times a week, did not have a substantial effect on the mean hemoglobin value. These results indicate that recombinant human erythropoietin (rHuEpo) is not beneficial to patients with CDA type I and that the relatively low levels of serum erythropoietin probably play no major role in the pathogenesis of the disease.

Effects of four species of interferon-alpha on cultured erythroid progenitors from congenital dyserythropoietic anaemia type I.

The in vitro effects of interferon (IFN)-alpha on erythroid progenitor cells derived from the peripheral blood of five patients with congenital dyserythropoietic anaemia (CDA) type I and seven healthy adults were studied. Ficol-hypaque-separated mononuclear cells were cultured for 14 d in StemGEM-1d medium with 0, 1, 10 and 100 U/ml of recombinant IFN-alpha2a, recombinant IFN-alpha2b, the genetically-engineered hybrid molecule IFN-alpha(1-8) or the laboratory-designed molecule IFN-alpha(consensus). Erythroid bursts and colonies were counted, picked and processed for electron microscopy. In the experiments employing IFN-alpha2a there were no differences in the numbers of erythroid bursts or colonies between four patients with CDA type I and seven healthy adults. All five patients with CDA type I showed the 'Swiss-cheese' ultrastructural abnormality of the heterochromatin in a proportion of the erythroblasts when the progenitor cells were cultured in the absence of added IFN-alpha. A statistically significant reduction in the proportion of erythroblasts showing the 'Swiss-cheese' defect was seen when the erythroid progenitors were cultured in the presence of 0.01-0.5 U/ml IFN-alpha2a (five patients), or 0.1 U/ml of IFN-alpha2b (two patients). In contrast, no reduction was seen in cultures containing 0.1-100 U/ml of either IFN-alpha(1-8) or IFN-alpha(consensus) or 20 microM hydroxyurea (two patients). The partial correction of the 'Swiss-cheese' abnormality by low concentrations of IFN-alpha2a in vitro provides an experimental model with which the mechanisms underlying the haematological response that occurs after the in vivo administration of this species of IFN-alpha may be investigated.

Congenital dyserythropoietic anaemias: clinical features, haematological morphology and new biochemical data

Three types of congenital dyserythropoietic anaemia (CDA) were originally identified on the basis of the pattern of dysplastic changes in the erythroblasts and the results of the acidified serum lysis test (Ham test). These were designated CDA types I, II and III. Several other types have been described subsequently and new forms continue to be reported. Some patients with CDA develop iron overload even without repeated blood transfusion and may present with the complications of severe iron overload. Dysmorphic features are seen in some cases, especially of CDA type I. In CDA type II, incomplete processing of N-linked oligosaccharides leads to a marked reduction of polylactosamines associated with band 3 of the red cell membrane. A few cases of CDA type III develop lymphoid neoplasms. Some of the Swedish cases of CDA type III have developed a retinal abnormality characterized by angioid streaks and macular degeneration. The chromosomal localizations of the disease gene in CDA types I and II and in the Swedish family with CDA type III are now known, but the identities of the mutant genes are still unknown. Cases of CDA type I have shown a partial haematological response to interferon-α, however the biochemical basis of this response is unclear. An important step in the diagnosis of sporadic cases of CDA is the exclusion of known causes of acquired dyserythropoiesis.

Effects of four species of interferon -&amp; on cultured erythroid progenitors from congenital dyserythropoietic anaemia type I

Summary. The in vitro effects of interferon (IFN)-a on erythroid progenitor cells derived from the peripheral blood of five patients with congenital dyserythropoietic anaemia (CDA) type I and seven healthy adults were studied. Ficolhypaque-separated mononuclear cells were cultured for 14 d in StemGEM-1d medium with 0, 1, 10 and 100 U/ml of recombinant IFN-a2a, recombinant IFN-a2b, the geneticallyengineered hybrid molecule IFN-a1-8 or the laboratorydesigned molecule IFN-aconsensus. Erythroid bursts and colonies were counted, picked and processed for electron microscopy. In the experiments employing IFN-a2a there were no differences in the numbers of erythroid bursts or colonies between four patients with CDA type I and seven healthy adults. All five patients with CDA type I showed the ‘Swiss-cheese’ ultrastructural abnormality of the heterochromatin in a proportion of the erythroblasts when the progenitor cells were cultured in the absence of added IFN-a. A statistically significant reduction in the proportion of erythroblasts showing the ‘Swiss-cheese’ defect was seen when the erythroid progenitors were cultured in the presence of 0·01‐0·5 U/ml IFN-a2a (five patients), or 0·1 U/ml of IFN-a2b (two patients). In contrast, no reduction was seen in cultures containing 0·1‐100 U/ml of either IFN-a1-8 or IFN-aconsensus or 20 mM hydroxyurea (two patients). The partial correction of the ‘Swiss-cheese’ abnormality by low concentrations of IFN-a2a in vitro provides an experimental model with which the mechanisms underlying the haematological response that occurs after the in vivo administration of this species of IFN-a may be investigated.

Localization of the Gene for Congenital Dyserythropoietic Anemia Type I to a

Congenital dyserythropoietic anemias (CDA) are a rare group of red-blood-cell disorders of unknown etiology that are characterized by ineffective erythropoiesis, pathognomonic cytopathology of the nucleated red blood cells in the bone marrow, and secondary hemochromatosis. In CDA type I, bone-marrow electron microscopy reveals characteristic findings in erythroid precursors, including spongy heterochromatin and enlarged nuclear pores. Since the genetic basis of CDA type I is not evident, we used homozygosity and linkage mapping to localize the genetic defect responsible for CDA type I in 25 Bedouins from four large consanguineous families. We report the linkage of this disease to markers on chromosome 15 located at q15. 1-q15.3. Fourteen markers within a 12-cM interval were typed in the relevant family members. Nine of the markers yielded maximum LOD scores of 1.625-12.928 at a recombination fraction of .00. Linkage disequilibrium was found only with marker D15S779. Haplotype analysis revealed eight different carrier haplotypes and highlighted the existence of a founder haplotype. Identification of historical crossover events further narrowed the gene location to between D15S779 and D15S778. The data suggest localization of the CDA type I gene within a 0.5-cM interval. The founder mutation probably occurred >/= 400 years ago. Sequence analysis of the coding region of protein 4.2, the only known erythroid-specific gene in the locus, did not reveal any change in the CDA type I patients. Future analysis of this locus may lead to the identification of a gene essential to normal erythropoiesis.

Defective glycosyltransferases are not good for your health.

The history of biochemical research on the structure and function of glycoproteins and glycolipids (glycoconjugates) dates back to the early 19th century (Montreuil, 1995). The variety of these macromolecules, their wide-spread distribution among all forms of life and their quantitative contribution to the bio-mass rank with those of proteins and nucleic acids. Nevertheless for a long period of time the lack of decisive information on the functions of glycoconjugates (Varki, 1993) discouraged most biochemists from entering this field. A series of discoveries over the past 25–30 years has slowly changed this attitude, e.g., the demonstration of mammalian lectins and of the association of defects in glycoconjugate metabolism with human diseases such as cancer, inflammatory and infectious diseases and various congenital diseases (Montreuil et al., 1996). Five autosomal recessive diseases have been reported to date (Table 1) in which a defect in the synthesis of asparagine-linked carbohydrate (N-glycans) has been clearly demonstrated. This presentation will focus on three of these diseases, carbohydrate-deficient glycoprotein syndromes Types I and II (CDGS I and II) and hereditary erythroblastic multinuclearity with a positive acidified serum lysis test (HEMPAS, Congenital Dyserythropoietic Anemia Type II). The study of these diseases should provide valuable information on the roles of N-glycans in human development.

Localization of the Congenital Dyserythropoietic Anemia II Locus to Chromosome 20q11.2 by Genomewide Search

Congenital dyserythropoietic anemias (CDA) are genetic disorders characterized by anemia and ineffective erythropoiesis. Three main types of CDA have been distinguished: CDA I and CDA III, whose loci have been already mapped, and CDA II (MIM 224100), the most frequent among CDAs, which is transmitted as an autosomal recessive trait and is known also as "HEMPAS" (hereditary erythroblast multinuclearity with positive acidified serum). We have recruited a panel of well-characterized CDA II families and have used them to search for the CDA II gene by linkage analysis. After the exclusion of three candidate genes, we ob-tained conclusive evidence for linkage of CDA II to microsatellite markers on the long arm of chromosome 20 (20q11.2). A maximum two-point LOD score of 5.4 at a recombination fraction of .00 was obtained with marker D20S863. Strong evidence of allelic association with the disease was detected with the same marker. Some recombinational events established a maximum candidate interval of approximately 5 cM.

Angioid streaks are part of a familial syndrome of dyserythropoietic anaemia (CDA III).

Congenital dyserythropoietic anaemia type III (CDA III) is a rare disease inherited in an autosomal dominant way and characterized by mild to moderate haemolytic anaemia. Most patients are adapted to their disease and have no or few complaints. Bone marrow examination shows a characteristic picture with erythroid hyperplasia and multinucleate erythroblasts. 20% of patients in a Swedish family affected with the CDA III condition have monoclonal gammopathy or multiple myeloma. By linkage and recombination analysis in the same family, the gene linked to the CDA III condition (CDAN3) has been located to chromosome 15q22. In this paper we report the observation of visual disturbances with macular degeneration and angioid streaks in six patients with CDA III and discuss the apparent association between CDA III, angioid streaks and monoclonal gammopathy. We suggest that this triad forms a previously unreported syndrome.

Reduced interferon-alpha production by Epstein-Barr virus transformed B-lymphoblastoid cell lines and lectin-stimulated lymphocytes in congenital dyserythropoietic anaemia type I.

The concentrations of interferon-alpha (IFN-alpha) in supernatants from cultures of Epstein-Barr virus (EBV) transformed B-lymphoblastoid cell lines derived from seven patients with congenital dyserythropoietic anaemia (CDA) type I were below the 95% confidence limits for those derived from six healthy subjects. In contrast, the concentrations of IFN-alpha in supernatants from cultures of EBV-transformed lymphoblastoid cell lines derived from four patients with other types of CDA and four patients with hereditary sideroblastic anaemia were normal. Supernatants from cultures of peripheral blood lymphocytes stimulated with phytohaemagglutinin or pokeweed mitogen contained less IFN-alpha when the cells were derived from patients with CDA type I than when derived from healthy subjects. Since patients with CDA type I show a substantial haematological response to treatment with IFN-alpha, the data suggest that impaired IFN-alpha production may be an important pathogenetic mechanism in CDA type I.

Neonatal manifestations of congenital dyserythropoietic anemia type I

Congenital dyserythropoietic anemia type I is a rare inherited bone marrow disorder characterized by macrocytic anemia with pathognomonic morphological ultrastructural features in erythroid precursors. The disease is usually not diagnosed in the neonatal period. In a retrospective study of 31 patients we found that 17 were first seen in the neonatal age with significant anemia (birth hematocrit 0.34 ± 0.07); 14 of the 17 infants also had early jaundice. Six infants were small for gestational age and two had syndactyly. Although rare, congenital dyserythropoietic anemia type I should be considered in the differential diagnosis of neonatal anemia. (J Pediatr 1997;131:95-7

Alpha-Mannosidase-II Deficiency Results in Dyserythropoiesis and Unveils an Alternate Pathway in Oligosaccharide Biosynthesis

Alpha-mannosidase-II (αM-II) catalyzes the first committed step in the biosynthesis of complex asparagine-linked (N-linked) oligosaccharides (N-glycans). Genetic deficiency of αM-II should abolish complex N-glycan production as reportedly does inhibition of αM-II by swainsonine. We find that mice lacking a functional αM-II gene develop a dyserythropoietic anemia concurrent with loss of erythrocyte complex N-glycans. Unexpectedly, nonerythroid cell types continued to produce complex N-glycans by an alternate pathway comprising a distinct α-mannosidase. These studies reveal cell-type-specific variations in N-linked oligosaccharide biosynthesis and an essential role for αM-II in the formation of erythroid complex N-glycans. αM-II deficiency elicits a phenotype in mice that correlates with human congenital dyserythropoietic anemia type II.

CLINICAL AND MOLECULAR ASPECTS OF CONGENITAL DYSERYTHROPOIETIC ANEMIA TYPE II 27

Congenital dyserythropoietic anemia type II (CDA-II) is the most frequent form of CDA. The inheritance pattern is autosomal recessive and its prevalence as well as the frequency of the gene are still unknown; this is due to the heterogeneity of clinical manifestations and to the fact that the majority of cases were probably undiagnosed.

Successful Treatment of Iron Overload by Phlebotomies in a Patient With Severe Congenital Dyserythropoietic Anemia Type II

To the Editor: A 32-year-old woman of Greek origin was referred to the hospital for evaluation of fatigue and symptomatical anemia. The anemia was documented 10 years ago during her first pregnancy. During the last 10 years the patient received an unknown number of red blood cell transfusions.