Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The percentages of minor adult hemoglobin (%Hb A2) in hemolysates and G gamma-globin chain (%G gamma) in fetal Hb (Hb F) of 15 individuals with elevated Hb F levels (2.0-11%) among 11,000 healthy Japanese adults were examined. Most of them might be carriers for the determinants of hereditary persistence of fetal hemoglobin. Subjects with less than 1.3% Hb A2, some of whom might be also carriers for delta-thalassemia determinants, had high G gamma values (54-70%). Those homozygous for a subhaplotype [+-----] 5' to the delta-globin gene had low to mid G gamma values (7-49%), while those homozygous for [-++-++] possessed high G gamma values (60-85%), but varied Hb F values (3.1-11%). Those heterozygous for the presence of the XmnI site 5' to (-158 bp to the cap site of) the G gamma-globin gene had mid to high G gamma values (53-65%). Factors for the high or low G gamma-globin gene expression in the Japanese adult with elevated Hb F level should be highly associated with a subhaplotype [-++-++] or [+-----], respectively.
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PMID:%Hb A2, %Hb F, %G gamma values and the haplotypes in the beta-globin gene cluster in Japanese adults with elevated Hb F. 138 Sep 45

Recently the molecular bases of thalassemia intermedia have been elucidated in several populations. In general this attenuated, non-transfusion dependent form of homozygous beta-thalassemia is mainly determined by a) the co-inheritance of deletion alpha-thalassemia; b) the presence of the so-called mild beta-thalassemia mutations; and more rarely, c) the inheritance of genetic conditions able to enhance the gamma-globin chain expression in adult life. Although there are several complex genetic and acquired interactions involved in the wide clinical heterogeneity of thalassemia intermedia, data in Italians indicate a definite genotype-phenotype relationship in conditions such as the co-inheritance of at least two alpha-thalassemia genes in severe and mild homozygous beta-thalassemia; the molecular homozygosity or double heterozygosity for the -87, -101 and IVS1(nt6) beta(+)-thalassemia mutations; and the coexistence of structural gamma-globin gene defects, i.e. Sicilian and Sardinian delta beta-thalassemias, deletional and non-deletional hereditary persistence of fetal hemoglobin and the polymorphism for the -158 XmnI G gamma restriction site. Thalassemia intermedia resulting from the inheritance in heterozygous beta-thalassemia of triple alpha-globin gene complex or the presence of dominant beta-thalassemia is also described and the role of these new informations in genetic counselling is discussed.
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PMID:[Current views of thalassemia intermedia]. 162 19

Monoclonal antibodies for the beta-globin chain of human HbA (UCH beta) and the gamma-globin chain of human HbF (UCH gamma) have been made. UCH beta indirectly labelled with rhodamine-labelled goat anti-mouse Ig and directly flouresceinated UCH gamma have been used, via double labelling immunofluorescence microscopy, to assay for the presence of beta-chains in fetal erythrocytes obtained at fetoscopy from fetuses at risk for beta-thalassaemia major. The results from 111 cases demonstrate that beta-chain synthesis of as low as 1.8% can be detected in fetal erythrocytes. The immunochemical labelling can be rendered more sensitive by the use of biotinylated UCH beta and avidin-FITC conjugates. This method is rapid and can be used for a sample that is highly contaminated with maternal erythrocytes.
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PMID:The use of monoclonal antibodies UCH beta and UCH gamma for the antenatal diagnosis of beta-thalassaemia. 243 15

Colonies derived from erythroid burst-forming units (BFU-E) synthesize fetal hemoglobin (HbF) in amounts that far exceed in vivo levels. There is some evidence that HbF synthesis is controlled at the level of a primitive erythroid precursor cell. Dexamethasone may potentiate the development of BFU-E. Since a means of augmenting HbF production in sickle cell anemia or severe beta-thalassemia would be of great therapeutic value, we studied the effects of dexamethasone on HbF and gamma-globin chain synthesis in BFU-E from patients with sickle cell anemia and controls. HbF was measured by radioimmunoassay of BFU-E lysate and gamma-chain synthesis by the incorporation of 3H-leucine into globin, which was then purified by gel filtration and column chromatography. Dexamethasone (10(-9) M) produced an increase in the number of BFU-E in 16 of 19 subjects when compared with numbers of BFU-E cultured with only erythropoietin. The individual BFU-E were larger and contained more subcolonies. Dexamethasone did not increase HbF or gamma-chain synthesis, and there was no relationship between proliferation of BFU-E and augmented HbF production. Thus, although dexamethasone augmented the development of erythroid bursts, there was no increment in HbF.
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PMID:Effects of dexamethasone on fetal hemoglobin synthesis in peripheral blood erythroid burst-forming units. 616 63

Individuals heterozygous for the Greek (A gamma) variant of hereditary persistence of fetal haemoglobin (HPFH) synthesize Hb F whose gamma-globin chains are predominantly of the A gamma type. DNA obtained from Greek HPFH heterozygotes was used to test for abnormalities in the organization of non alpha-globin genes. In addition, gamma- and beta-globin expression was studied in BFUe cultures. Restriction endonuclease mapping showed that the G gamma, delta and beta genes in cis to the Greek HPFH determinant are intact. Overproduction of gamma-globin chains synthesis was observed in the BFUe cultures. A significant portion of the gamma chain synthesis was of the G gamma type, suggesting that the G gamma genes cis and trans to the HPFH chromosome are active in culture. DNA mapping data indicate that in contrast to G gamma A gamma HPFH and the G gamma (delta beta) thalassaemia, the Greek (A gamma) HPFH is not due to a large deletion in the non-alpha globin gene region. It is possible that the anomaly may result either from a small deletion or point mutation which influences non alpha-globin transcription. The in vitro synthesis data suggest that the low level of G gamma-globin chain synthesis in vivo is not the result of transcriptional inactivation of the G gamma gene, since this gene appears to be expressed in erythroid cell cultures. We speculate that the genetic lesion in Greek (A gamma) HPFH is in regulatory sequences which control the level of G gamma and A gamma expression during development.
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PMID:Greek (A gamma) variant of hereditary persistence of fetal haemoglobin: globin gene organization and studies of expression of fetal haemoglobins in clonal erythroid cultures. 617 32

Homozygous beta-thalassemia is usually characterized by severe anemia requiring regular blood transfusion for survival. For homozygous patients with milder clinical manifestations and no dependence on transfusion therapy, the term thalassemia intermedia is usually applied. Genetic mechanisms that may ameliorate the clinical expression of homozygous beta-thalassemia include coinheritance of alpha-thalassemia, inheritance of mild beta-globin gene mutations, and increased gamma-globin chain production, which may partially compensate for the lack of beta-globin chain synthesis. To identify which of these factors may contribute to the modification of childhood homozygous, high-hemoglobin A2 (HbA2) beta-thalassemia in Greece, the interaction of alpha-thalassemia, types of beta-thalassemia mutations, and the presence of a polymorphic site 5' to the G gamma-globin gene, which has been described as associated with increased gamma-globin chain production in some cases, was assessed. The results were analyzed in light of similar studies in 150 randomly selected, homozygous, high-HbA2 beta-thalassemia patients with the aim of assessing whether thalassemia genotypes can provide information useful for prognosis and/or more appropriate management of homozygous beta-thalassemia patients. The results indicate that, in general, the major factor modifying the clinical expression of homozygous, high-HbA2 beta-thalassemia in Greece is the inheritance of mild beta-thalassemia mutations. Although there is not always a complete correlation of genotype with clinical phenotype, the inheritance of two mild beta-thalassemia alleles results in almost all cases (11 of 12 cases in this study) in thalassemia intermedia phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Molecular characterization of homozygous (high HbA2) beta-thalassemia intermedia in Greece. 770 40

The hereditary persistence of fetal hemoglobin (HPFH)-6 is sporadically found in Thailand whereas the deletion-inversion type (G)gamma((A)gamma delta beta)(0)-thalassemia is described among Indians. We report a hitherto un-described case in which these two defects co-segregate. He was a 3-year-old Thai boy who had a feature of thalassemia intermedia phenotype with the following hematologic data; Hb 8.8 g/dL, Hct 29.2%, MCV 66.9 fL, MCH 20 pg, and MCHC 30.1 g/dL. Hemoglobin analysis revealed 100% Hb F with only (G)gamma-globin chain. Globin gene analyses demonstrated that he carried the HPFH-6 deletion in trans to the Indian deletion-inversion (G)gamma((A)gamma delta beta)(0)-thalassemia. Hematologic data of the patient was compared to those of the HPFH-6 heterozygote found in his father, to (G)gamma((A)gamma delta beta)(0)-thalassemia heterozygotes detected in his mother and sister, and to that of an unrelated Thai patient who was a compound heterozygote for the deletion-inversion (G)gamma((A)gamma delta beta)(0)-thalassemia and HbE.
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PMID:Molecular and hematological characterization of HPFH-6/Indian deletion-inversion Ggamma(Agammadeltabeta)0-thalassemia and Ggamma(Agammadeltabeta)0-thalassemia/HbE in Thai patients. 1235 10

We report the molecular and hematological characterizations of thalassemia caused by interactions of the hereditary persistence of fetal hemoglobin (HPFH)-6 with beta-thalassemia in 2 Thai patients and the HPFH-6 with Hb E in another Thai patient. Marked hypochromic microcytosis, characteristics of thalassemia intermedia, were obvious in the former 2 cases but the latter had much milder clinical phenotype with normal Hb and a slightly reduced mean corpuscular volume (MCV) value. Hb analysis revealed no Hb A but Hb A(2)F patterns in the compound HPFH-6/beta-thalassemia patients and the EF pattern in the HPFH-6/Hb E patient. The (G)gamma-globin chain predominated in all cases. Globin gene analyses demonstrated that all patients carried the 101-kb HPFH-6 deletion in trans to the beta-thalassemia genes with the IVS1#5 G-C mutation and the G insertion between codons 8/9 and the beta(E)-gene, respectively. Hematologic data of the patients were compared to those of the HPFH-6 heterozygotes found in their family members and different genotype-phenotype interactions of this HPFH determinant in these Thai patients are illustrated.
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PMID:Molecular characterization of thalassemia intermedia associated with HPFH-6/beta-thalassemia and HPFH-6/Hb E in Thai patients. 1237 89

Beta-Thalassemia is the most common single gene disorder in the world, which is caused by the imbalance between alpha-globin chain and beta-globin chain synthesis. Several medicines, such as 5-azacytidine, hydroxyurea, cytarabine, vinblatine, butyrate, and myleran, have been shown to be able to reactivate gamma-globin chain synthesis during the adult stage, and some of them (5-azacytidine, hydroxyurea, myleran, and butyrate) have been used clinically to treat thalassemia and sickle cell disease. Much research efforts are focusing on the determination of the underlying mechanisms of medicine action. In this experiment, as an effort to probe the underlying mechanism of medicine action, we used ligation-mediated polymerase chain reaction and in vivo footprinting methods to study the DNA-protein interaction at critical erythroid regulatory elements after hydroxyurea or myleran administration to mice. Our results showed that the patterns of in vivo footprints at both the hypersensitive site 2 of the locus control region and the beta-globin gene promoter were changed after medicine treatment. We proposed based on these results that the medicines' administration might result in a change in the interaction between trans-acting factors and cis-acting elements at these regions. These changes might influence the assembly of the transcription complex and, lastly, influence the expression of the beta-globin gene.
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PMID:Effect of fetal hemoglobin-stimulating medicines on the interaction of DNA and protein of important erythroid regulatory elements. 1456 2

Reactivation of fetal hemoglobin (HbF) expression is an important therapeutic option in patients with hemoglobin disorders. In sickle cell disease (SCD), an increase in HbF would interfere with the polymerization of sickle hemoglobin while in beta-thalassemia, an increase in gamma-globin chain synthesis would decrease non-alpha:alpha chain imbalance. Hydroxyurea, an inducer of HbF, is the only currently approved agent for the treatment of patients with moderate and/or severe SCD. However, about one third of patients with SCD do not respond to HU, and in beta-thalassemia, the clinical response is unimpressive. The last decade has seen a renewed interest in the use of inhibitors of DNA methylation in the treatment of patients with hemoglobin disorders. In this review, we discuss the role of DNA methylation in gamma-globin gene regulation, describe clinical trials with agents that hypomethylate DNA and speculate about the future role of DNA hypomethylation therapy in patients with SCD and beta-thalassemia.
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PMID:DNA hypomethylation therapy for hemoglobin disorders: molecular mechanisms and clinical applications. 1651 30


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