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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The study of 176 subjects with beta-thalassemia, associated or not with a hemoglobinopathy, shows great diversity. The hemoglobin C thalassemias are less severe and form a fairly homogeneous group. Sickle cell thalassemia cases have more marked anemia and the disease takes on more varied forms, no doubt because the main mechanism of the anemia, the hyperhemolysis, is influenced by several factors which have a variable effect on the clinical picture. Unassociated thalassemias seem the most polymorphic. Although it seems that in certain foci the beta-thalassemias are fairly stereotyped, this first study shows in Algeria great heterogeneity. All forms are observed both clinically and in the laboratory. Present classifications have not supplied a sufficiently operative model. It is not doubt necessary to await further progress in the laboratory to classify these diseases more precisely.
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PMID:[Clinical and biological aspects of beta-thalassemia. Apropos of 176 cases]. 19 8

In this paper are brought the results obtained in two Parisian hospitals during a survey of abnormal hemoglobins in 540 immigrant workers coming from Africa, mostly from Mali, Mauritania and Senegal. All the subjects investigated were male and between 20 and 40 years old. The studies were performed following internationally standardized technics. The most frequent abnormalities were: Hb S found in 16.3%, Hb C (6.6%), alpha-thalassemia trait (3.1%) and beta-thalassemia trait (3.1%). Some rare abnormalities were also found: delta-chain variants, hereditary persistance of foetal hemoglobin, Hb Hope and Hb Grady. This work emphasizes the high frequency of the different hemoglobin disorders in this population. The easy diagnostic of electrophoretically detectable variants is compared to the more complex situation of thalassemia leading probably to an under estimation of the percentage.
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PMID:[Hemoglobinopathies in West-African immigrant workers in France (author's transl)]. 21 87

Using a method involving elution of hemoglobin bands from cellulose acetate strips following electrophoresis of hemolysates, hemoglobin A2 (Ab A2) was quantitated in bloods from 300 healthy individuals and 904 patients. The percentage of Hb A2 was elevated in beta-thalassemia heterozygotes and some patients who had megaloblastic anemia. In the latter, the highest Hb A2 levels were observed in patients with the most severe anemia. Low Hb A2 percentages were found in iron-deficiency anemia, hereditary persistance of fetal hemoglobin, and Hb H disease. In iron-deficiency anemia, the lowest levels of Hb A2 were observed in association with the most severe anemia. Iron and folate deficiency each suppressed Hb A2 levels in beta-thalassemia heterozygotes; however, vitamin B12 deficiency did not alter the percentage of Hb A2 in thalassemia. Malignant tumors, renal and hepatic insufficiency, chronic infections and inflammation, hemolytic disease, lead poisoning, aplastic anemia, leukemia, myelofibrosis, and hypothyroidism did not change Hb A2 levels. The pathogenesis of altered Hb A2 levels and their clinical significance in various diseases are discussed.
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PMID:Hemoglobin A2 levels in health and various hematologic disorders. 26 35

In a patient with homozygous betaO-thalassemia in whom studies of reticulocyte hemoglobin synthesis showed no beta-globin chain synthesis in vivo and in vitro, molecular hybridization studies revealed RNA sequences complementary to beta-globin cDNA. The fact that these sequences were authentic beta-globin mRNA was shown by fingerprint analysis of T1 ribonuclease-digested mRNA and by sequencing of oligonucleotides unique to beta-globin mRNA. The beta-mRNA that failed to direct beta-globin chain synthesis was not detectably shortened or degraded and contained poly(A) sequences.
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PMID:Authentic beta-globin mRNA sequences in homozygous betaO-thalassemia. 26 54

Human cellular DNA fragments from cells of normal subjects and patients with thalassemia obtained by restriction enzyme digestion were analyzed for their globin gene content. The fragments were separated on agarose gels, transferred to nitrocellulose filters, hybridized to globin [(32)P]cDNA, and radioautographed. One to ten picograms of globin gene sequences were detectable. With EcoRI digestion, eight to nine cellular DNA fragments were found to contain globin genes. Three of these contained beta-like gene sequences assayed with beta globin cDNA probe. One beta-like fragment was absent in DNA from a homozygous subject for hemoglobin Lepore. Two of the three beta gene-containing fragments present in normal DNA were absent in DNA from a patient with hereditary persistence of fetal hemoglobin. The same two fragments containing beta-like genes were absent from deltabeta thalassemic DNA and one new fragment containing beta-like genes was found. Together with results obtained by hybridization of these DNAs in solution, the data are consistent with deletion of specific restriction human DNA fragments in subjects with these disorders and a greater deletion of beta-like gene sequences in subjects with hereditary persistence of fetal hemoglobin than in those with deltabeta thalassemia.
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PMID:Changes in restricted human cellular DNA fragments containing globin gene sequences in thalassemias and related disorders. 27 14

Thalassemia is characterized by unequal rates of synthesis of the alpha and beta globin chains that are part of the hemoglobin tetramer. In the type of thalassemia due to a defect in beta-chain synthesis (beta-thalassemia), this imbalance results in a relative exoess of alpha-chains. We have studied the susceptibility of excess free alpha-chains to proteolysis. Incubation of isotopically labeled peripheral blood lysates from individuals with beta-thalassemia trait in the presence of bone marrow or normoblast lysates from thalassemic or hematologically normal individuals resulted in a decrease in the alpha/beta ratio and a loss of free alpha-chain radioactivity. Neither contamination with leukocytes nor higher ATP contents in young erythrocytes appeared to be responsible for this activity in normoblasts and bone marrow. We propose that erythroid precursor cells possess proteolytic activity that is markedly diminished in mature cells. This activity serves an important control function in the regulation of hemoglobin synthesis. It accounts at least in part for the more balanced synthesis of alpha- and beta-chains observed in bone marrow than in peripheral blood in heterozygous beta-thalassemia. It also plays a fine-tuning role in maintaining balanced synthesis in non-thalassemic erythrocytes.
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PMID:Proteolytic activity in erythrocyte precursors. 27 45

Thalassemia major is a severe and transfusion-dependent anemia that occurs in persons homozygous for a mutation that affects the capacity for synthesis of the beta-globin subunit of hemoglobin. Characterization of the molecular defects that cause beta-thalassemia is providing insight into the mechanism of globin gene regulation. Newer approaches to the management of thalassemia major include more effective chelation by use of subcutaneous desferrioxamine and attempts to obtain young erythrocytes with a longer potential for survival in recipient patients. Development of more effective chelators that may be given orally is an ongoing effort. Noninvasive evaluation of cardiac structure and function in patients with thalassemia major suggests that myocardial iron deposits begin at an early age, causing functional impairment long before the onset of clinical symptoms. Prevention or reversal of these cardiac abnormalities remains the goal of chelation therapy.
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PMID:Thalassemia major: molecular and clinical aspects. NIH Conference. 39 Nov 18

Many mutant hemoglobins and hemoglobinopathies can be identified with a high degree of specificity in the routine clinical laboratory. The most frequent abnormalities--those involving Hb S or C--are usually easily detectable in small amounts of sample analyzed by two simple methods of electrophoresis: cellulose acetate at pH 8.5 and citrate agar at pH 6. Some rarer mutants, e.g., Hb O, Hope, and Camden, can also be recognized by these two methods. Presumptive identification of other relatively frequent mutants, such as Hb D Los Angeles (Punjab) and Hb G Philadelphia, can be accomplished with additional data obtained from globin electrophoresis on cellulose acetate in acidic and alkaline buffers containing urea and 2-mercaptoethanol (or dithioerythritol). Electrophoretic profiles are presented of about a dozen hemoglobins likely to be encountered in screening programs in the U.S. Methods are also presented for identifying other genetic hemoglobin abnormalities--various types of thalassemia, Hb M, unstable hemoglobins, and those of the newborn.
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PMID:Methods for detection of hemoglobin variants and hemoglobinopathies in the routine clinical laboratory. 40 71

Heterozygous classical beta-thalassemia was found in 13 subjects of pure German descent, 11 of them from the Bergische Land (NW Germany) during the past three years. Clinically it became manifest in a moderate degree of anemia with marked hypochromia and reduced mean corpuscular volume. The number of red blood corpuscles and the value for serum iron were ascertained to be in the upper limits of normal or raised. The diagnosis of Mediterranean anemia was confirmed by hemoglobin electrophoresis with a rise in HbA2 of more than 3%. A slight increase in HbF may also occur. The importance of genetic counseling of thalassemia patients is emphasized. The occurrence of thalassemia even in pure German populations must be increasingly reckoned with.
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PMID:[Thalassemia minor in families of German descent in the Bergische Land (author's transl)]. 40 46

Minor fetal hemoglobins in red cell hemolysates of newborn and adults with elevated levels of Hb F have been separated and quantitated by Biorex 70 column chromatography. In addition to Hb F1, other minor hemoglobin zones eluting before F1, pre-F1, and after F1, post-f1 have been observed. The relative amounts of the two pre-F1 zones and F1 are higher in the red cells of adults with 97--100% Hb F (homozygous hereditary persistence of fetal hemoglobin, homozygous deltabeta-thalassemia and homozygous beta0-thalassemia) than in the red cells of an adult with homozygous beta+-thalassemia with 66% Hb F, a child with a trisomy-D-13 having 38% Hb F, and in two newborn. Hb F was glycosylated in vitro with [14C]glucose or [14C] glucose 6-phosphate, and was acetylated using chicken reticulocyte lysate or a crude acetyltransferase preparation isolated from the same lysate with [14C]acetyl-CoA as substrate. Chromatographic analyses indicated that the Hb F1 zone can be formed both by glycosylation and acetylation of Hb F, and that pre-F1 zones can be products of the reaction of Hb F with phosphorylated glycolytic intermediates. Biosynthesis of minor hemoglobins in reticulocytes was studied with [14C]leucine in the presence and absence of cycloheximide and by pulse-chase. The resulting data indicate that Hb F1 synthesis is dependent upon Hb F synthesis and that the posttranslational modification may take place at an early stage in Hb F synthesis.
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PMID:On the chromatographic heterogeneity of human fetal hemoglobin. 42 12


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