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

Facilities for the antenatal diagnosis of homozygous beta thalassaemia have recently become available in Australia and in this paper, data from a series of 18 pregnancies examined at The Royal Women's Hospital, Melbourne, are analysed. Fetal blood was collected by fetoscopy and adequate samples were obtained in 16 cases (89%). In 5 pregnancies, fetal blood was shown to have a marked reduction in beta globin production (beta/alpha synthesis less than 0.030) and these pregnancies were terminated. Two pregnancies (11%) were lost in the immediate post-fetoscopy period and in a third pregnancy, neonatal death followed premature labour at 26 weeks' gestation. Seven babies were delivered normally at 36-40 weeks' gestation and cord blood studies excluded homozygous thalassaemia in all cases. The remaining pregnancy has yet to be delivered.
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PMID:Antenatal diagnosis of homozygous beta thalassaemia in Mediterraneans in Australia. 695 60

Four patients with idiopathic myelofibrosis were found to have microcytic and/or hypochromic red cell indexes. The alpha/beta globin synthetic ratio determined by incubating peripheral blood with [14C]leucine was within normal limits in all patients studied. This is unlike a recent report of acquired hemoglobin H disease with decreased alpha/beta synthetic ratio in primary myelofibrosis. This indicates that mechanisms other than alpha-thalassemia-like defects may also be involved in the production of microcytic and hypochromic red cells in myelofibrosis.
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PMID:Balanced globin synthesis in idiopathic myelofibrosis. 722 30

The separation of alpha, beta, G gamma and A gamma globin chains by reversed phase high pressure liquid chromatography has been studied using columns of octadecylsilyl-silica. All separations were performed in solvent mixtures of water and acetonitrile acidified with phosphoric acid or the hydrophobic ionpairing reagent trifluoroacetic acid. The addition of trifluoroacetic acid or the chaotropic agent NaClO4 to the mobile phase increased the resolution and the peak sharpness of the eluted globin chains. The use of decreasing gradients of TFA or NaClO4 and chromatography at 40 degree were useful steps for the separation of alpha and beta globin chains, a prerequisite for the successful application of this method for the prenatal diagnosis of beta-thalassemia. The beta/gamma synthetic ratio obtained from blood samples taken by fetoscopy from normal fetuses and fetuses with beta-thalassemia trait were measured simultaneously by CM-cellulose chromatography and high pressure liquid chromatography. The values obtained by HPLC were very similar but slightly lower than those obtained by CM-cellulose chromatography. The new method is fast and accurate and will prove to be useful for prenatal diagnosis involving globin chain separation.
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PMID:Reversed-phase high pressure liquid chromatography of globin chains: its application for the prenatal diagnosis of beta-thalassemia. 727 70

Hematologic evaluation of a Nigerian obstetrical patient disclosed the presence of sickle-cell trait as well as evidence of a hemoglobin alpha-chain abnormality. Hemoglobins containing the variant alpha-chain were isolated by DEAE-cellulose column chromatography, and analysis of the purified alpha-chain demonstrated a ser replaced by cys substitution at alpha-81. The abnormal alpha-chain represented approximately 45% of the total, and hemoglobins containing this alpha-chain appeared to have normal stability and functional properties. In addition to the abnormal hemoglobins that were identified in this patient, she also was found to have persistent microcytosis in the absence of iron deficiency, and the percentage of HbS in her erythrocytes was less than that usually present in individuals with sickle cell trait. These findings, together with a reduced alpha/beta globin synthesis ratio from her peripheral blood reticulocytes, indicated that the presence of alpha-thalassemia trait. Hematologic findings from members of the patients's family suggest that an alpha-thalassemia gene may be linked to that of the structurally abnormal alpha-chain.
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PMID:Hemoglobin Nigeria (alpha-81 Ser replaced by Cys):a new variant associated with alpha-thalassemia. 735 Sep 33

Hemoglobin H disease usually occurs as a result of inheritance of the genes for alpha thalassemia; however, occasionally patients acquire hemoglobin H in association with hematologic malignancy. This report concerns a 63-year-old Filipino man with a myeloproliferative syndrome with marked thrombocytosis and apparently acquired hemoglobulin H disease. The patient had hemolytic anemia, dimorphic red blood cells (RBC) and abundant ringed sideroblasts in the marrow. The peripheral blood contained 27% hemoglobin H and about two-thirds of his RBC had hemoglobin H inclusion bodies. There was no previous history of anemia or evidence of thalassemia in two siblings or nine adult children of the patient. In vitro studies of globin chain synthesis documented markedly decreased production of alpha globin with alpha/beta biosynthetic ratios of 0.05 in peripheral blood reticulocytes and 0.10 in bone marrow cells. The relative concentration of mRNA for alpha globin was approximately 20-fold less than that of beta globin, apparently accounting for the deficiency in alpha globin synthesis.
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PMID:Myeloproliferative syndrome with sideroblastic anemia and acquired hemoglobin H disease. 735 Oct 8

The possibility of using alpha/beta globin messenger RNA (mRNA) ratios to distinguish between the carrier states for different forms of alpha thalassaemia has been explored. Alpha/beta globin mRNA ratios were determined in the red cells of a series of normal individuals and in members of four Cypriot families, one Thai and one Chinese family in which at least one person has haemoglobin H disease. It was found that there was a clear distinction in the ratios between normals, alpha thalassaemia 1 carriers, alpha thalassaemia 2 carriers, and those with haemoglobin H disease. This method should be a valuable addition to haematological analysis, haemoglobin synthesis and restriction mapping of DNA for the further elucidation of the genetics of alpha thalassaemia.
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PMID:Determination of alpha thalassaemia phenotypes by messenger RNA analysis. 737 29

The different alpha thalassemia genotypes in American and Jamaican black populations have been defined by hematologic and globin-chain synthesis studies, alpha/beta globin messenger RNA ratios and restriction endonuclease mapping of DNA. The results indicate that the common form of alpha thalassemia in these populations is the deletion type of alpha-thalassemia 2 (- alpha/alpha alpha). The homozygous state (- alpha/alpha- alpha) is expressed at birth by the presence of more than 2--3% hemoglobin Bart's; in adult life it has the same phenotype as the heterozygous state for the deletion form of alpha-thalassemia 1 (--/alpha alpha). The heterozygous state is not always associated with detectable amounts of hemoglobin Bart's at birth or with recognizable hematologic changes in adults.
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PMID:alpha thalassemia in black populations. 738 54

Haemoglobin E (alpha 2 beta 2(26)Glu leads to Lys) is one of the commonest haemoglobin variants. There are an estimated 30 million carriers of the beta E gene in South-East Asia, where they comprise more than 50% of the population in some areas; however, the reasons for this high frequency have never been adequately explained. Homozygotes for HbE may be midly anaemic, but they do not have any clinical disability. However, individuals heterozygous for both beta E and beta thalassaemia (HbE/beta thalassaemia) have a severe clinical disorder which in some cases may approach that seen in homozygous beta thalassaemia and which is by far the commonest form of symptomatic thalassaemia in the Indian subcontinent and South-East Asia. Haemoglobin E is the only common structural variant which interacts with beta thalassaemia to produce a severe disorder and the underlying mechanism of the interaction is not known. We have studied several homozygotes and heterozygotes for HbE and show here that the beta E chain is inefficiently synthesized and produces the phenotype of a mild form of beta thalassaemia; hence, when inherited together with beta thalassaemia it causes a marked beta-chain deficit. Furthermore, the mechanism for the defective production of beta E chains seems to be a reduction of beta E mRNA, a most unexpected finding in a disorder caused by a single amino acid substitution and presumably by a single nucleotide change in the DNA of the beta globin gene.
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PMID:Defective synthesis of HbE is due to reduced levels of beta E mRNA. 744 96

mRNA-cDNA hybridization, intact reticulocytes biosynthesis and heterologous cell-free translation studies have been performed in cases of heterozygous beta and delta beta thalassaemia. Results obtained have shown that the relative amount of beta mRNA is higher in Ferrara microcytes than in other heterozygous including delta beta. This indicates that transcription of beta globin gene takes place in Ferrara beta 0 thalassaemia. On the contrary globin biosynthesis studies have failed to show clear-cut differences among the various heterozygous considered and cannot evaluate the translatability of beta thal. FemRNA.
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PMID:[Messenger RNA in cases of heterozygous beta and delta-beta Thalassemia. Biosynthetic and hybridization studies]. 744 19

A Chinese family has been studied in which two siblings have haemoglobin Q-H disease. Using a combination of haematological and haemoglobin analysis, globin chain synthesis, analysis of alpha/beta globin messenger RNA ratios and restriction endonuclease mapping, it has been shown that each of these siblings has received one chromosome on which both alpha chain genes have been deleted and another on which there is only a single alpha chain locus which carries the alpha Q mutation. Their genotype is thus --/-alpha Q. Despite the fact that the haemoglobin Q mutation in this family is carried on a chromosome with a single alpha chain locus, heterozygous carriers for the variant have only 25% or less haemoglobin Q. Our observations indicate that the molecular basis for haemoglobin Q-alpha thalassaemia is similar to that for the common form of haemoglobin H disease in Orientals. Furthermore, they provide clear evidence that the level of an alpha chain variant in heterozygous carriers is not a reliable reflection of the number of alpha globin genes.
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PMID:The genetic basis of Hb Q-H disease. 744 25


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