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

Haemoglobin F has been isolated from the red cells of individuals with the Greek form of hereditary persistence of fetal haemoglobin (HPFH), and the glycine/alanine composition of the gamma CB3 peptides determined. In contrast to previous reports we have shown that the Hb F of the Greek HPFH heterozygotes contains significant amounts of G gamma chains and circumstantial evidence indicates that these are the products of the same chromosome that carries the Greek HPFH determinant. Hence this chromosome must be directing the synthesis of G gamma, A gamma and (probably) beta and delta chains, thus implying that the Greek form of HPFH does not result from a deletion involving the globin chain structural genes. Analysis of the levels and structure of Hb F from the Greek HPFH heterozygotes and from separated cell populations from the Greek HPFH/beta thalassaemia compound heterozygotes indicate that the Greek HPFH determinant, while allowing an overall increase in gamma chain synthesis, is not the sole factor determining the absolute amount of Hb F production on a cellular basis.
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PMID:Occurrence of G gamma Hb F in Greek HPFH: analysis of heterozygotes and compound heterozygotes with beta thalassaemia. 9 88

The synthesis of fetal hemoglobin was investigated in in vitro cultures of erythroid precursors isolated from peripheral blood of normal individuals, newborns and of subjects with different hemoglobinopathies. Synthesis of hemoglobin was assessed by 35s-methionine labeling of cultures and measurement of the radioactivity incorporated into the hemoglobins A2, A, F and S isolated by column chromatography on DE 52 cellulose. The erythroid precursors from most of the studied individuals cultured in in vitro system responded with synthesized an average of 15% of Hb F while cultures from newborns produced an average of 60% of Hb F in comparison of 73% of Hb F in peripheral blood of the same newborns. Erythroid precusors from subjects heterozygotes for beta-thalassemia, heterozygotes for HPFH, and homozygotes for Hb S produced an average of 20%, 43% and 30% of Hb F, respectively, in comparison of 7%, 14% and 9% of Hb F, respectively, present in the RBC of the same individuals. These data support the previously published results (6-11) that erythroid bursts in culture reactivate the structural genes for the gamma chain synthesis.
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PMID:[Preferential synthesis of fetal hemoglobin in in vitro cultures of erythroid precursors from peripheral blood of healthy persons and those with hemoglobinopathies]. 9 30

Nine patients have been observed with homozygous beta thalassaemia in each of whom one parent has a normal level of Hb A2. On the basis of clinical, haematological and globin chain synthesis studies these families have been divided into two groups. Group 1 (six families). Heterozygotes for normal Hb A2-beta thalassaemia in this group showed minimal red cell abnormalities, normal osmotic fragility but imbalanced globin chain synthesis (alpha/beta=1.6), and appear to correspond to previous descriptions of 'silent' beta thalassaemia. Double heterozygotes with high Hb A2-beta thalassaemia have a clinical picture of mild beta thalassaemia intermedia characterized by relatively low levels of Hb F (less than 20%) and gamma chain synthesis. Group 2 (three families). beta Thalassaemia heterozygotes with normal HbA2 levels in this group showed more marked red cell abnormalities, decreased osmotic fragility and more imbalanced globin chain synthesis (alpha/beta=2.5) than those in group I. Double heterozygotes with high Hb A2-beta thalassaemia are more severely affected and are transfusion dependent. Haemoglobin F and gamma chain synthesis are high in these cases. The frequency of normal Hb A2-beta thalassaemia in Greece may be as high as 10% of all beta thalassaemia genes and this poses a significant problem for genetic counselling. Various molecular mechanisms are discussed which could account for the heterogeneity within these disorders.
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PMID:The heterogeneity of normal Hb A2-beta thalassaemia in Greece. 46 53

The biosynthesis of two types of human fetal hemoglobin (Hb F), namely Hb F with G gamma chains having glycine in position 136 and Hb F with A gamma chains having alanine in position 136, was studied in blood samples and in cultures of erythroid precursors from blood of patients with different hemoglobinopathies. High pressure liquid chromatography (HPLC) was adapted to allow the separation of the methionyl-containing tryptic peptides G gamma T-15 and A gamma T-15 (which include the Gly leads to Ala polymorphism at position 136) from a digest of microquantitites of 35S-methionyl labelled Hb F. This method was sensitive enough to quantitate the relative production of the G ygamma and A gamma chains by erythroid colonies derived from cloned Burst Forming Units (bfu-e) which were cultured for 16 days on methylcellulose. The production of Hb F in these colonies was generally higher than the level of Hb F in blood except for subjects with the G gamma A gamma-HPFH heterozygosity. The G gamma to A gamma ratio in the Nb F produced in cultures of cells from G gamma delta beta-thalassemia or G gamma-HPFH heterozygotes was lower and that from A gamma-HPFH heterosygotes was higher than the ratios in the Hb F of the corresponding peripheral blood cells. Mixtures of G gamma and A gamma chains were present in cell cultures of SS patients, beta+-thalassemia homozygotes and G gamma A gamma-HPFH heterozygotes in a ratio similar to that in the Hb F of mature red cells. These data suggest that erythroblasts in BFU-E derived colonies reactivate all available gamma chain structural genes, both in cis and in trans to the abnormal determinant. Hb F biosynthesis by adult blood samples concerns primarily the G gamma chains. This was particularly striking for blood samples in which erythroblasts were absent and the biosynthesis took place in fetal reticulocytes. Thus, the F-retuculocytes in blood of A gamma-HPFH heterozygotes with about 5% Hb F of the A gamma type produced primarily Hb F with G gamma chains. Similar differences were observed for G gamma A gamma-HPFH heterozygotes and, less strinkingly, for SS patients. A satisfactory explanation for this observation has not yet been obtained.
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PMID:The synthesis of fetal hemoglobin types in red blood cells and in BFU-E derived colonies from peripheral blood of patients with sickle cell anemia, beta+ - and delta beta-thalassemia, various forms of hereditary persistence of fetal hemoglobin, normal adults and newborn. 50 Mar 69

Three patients with a relatively mild form of beta O-thalassemia who did not require regular blood transfusions are described. Globin synthesis was studied by gel filtration and urea-carboxymethylcellulose chromatography of stroma-free hemolysates prepared from peripheral blood and bone marrow cells labeled in vitro with 14C-leucine. gamma/alpha Synthetic ratios in peripheral blood were in the same range as in patients with the severe clinical form of beta O-thalassemia, while gamma/alpha synthetic ratios in bone marrow cells were higher than in that group of patients. The size of the free alpha-chain pool measured in one case was smaller than in other patients with "classical" Cooley anemia. It is concluded that the severity of the clinical course in beta O-thalassemia does not correlate with the imbalance in alpha verus gamma chain synthesis in peripheral blood and is determined by the synthetic ratio in bone marrow cells, where the bulk of hemoglobin synthesis takes place.
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PMID:Beta O-thalassemia intermedia. 66 61

A previously unrecognized hypochromic anemia associated with marked normoblastemia during the newborn period is reported. One male and two female siblings and a first cousin had a hypochromic anemia and marked normoblastemia (300 to 900 normoblast index per 100 white blood cells) at birth. Globin chain synthesis studies on peripheral blood of the proband at birth indicated the presence of alpha-thalassemia trait with possible reduced gamma chain synthesis. Studies of globin chain synthesis on the father, two older affected siblings of the proband, and the proband at 1.5 years of age revealed alpha-thalassemia trait. The data suggest this complex alpha-thalassemia-like condition as a new syndrome associated with marked neonatal normoblastemia.
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PMID:Complex alpha-thalassemia-like syndrome: a cause of neonatal normoblastemia. 95 73

DNA has been prepared from peripheral blood or cultured skin fibroblasts obtained from three Sicilian and one Greed deltabeta-thalassemia homozygotes. Globin-gene analysis was carried out using a cDNAbeta probe, and the results indicate that deltabeta-thalassemia has arisen from a deletion of the beta-globin genes. A similar result was obtained using DNA prepared from cultured skin fibroblasts from an individual homozygous for the Negro form of hereditary persistence of fetal hemoglobin (HPFH). In both cases, the deletion has spared the Ggamma and Agamma loci directing the gamma chains of hemoglobin F, but it has not been possible to demonstrate any difference between the size of the deletion involved in the production of delta-beta-thalassemia and that which gave rise to HPFH. These experiments provide further direct evidence that deletions of critical areas of the gamma-delta-beta gene cluster result in persistent gamma chain synthesis in adult life.
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PMID:Delta-beta-thalassemia is due to a gene deletion. 97 41

The clinical, haematological and biochemical findings in a person with delta beta-thalassaemia and Hb-Lepore are described. The patient was a 24-year-old student who suffered from anaemia of intermediate severity with late onset of the clinical manifestations, had minor bone and facial deformities, but had no necessity for regular transfusions. Haemoglobins A and A2 were absent in this individual, and the Hb-Lepore has been identified as Lepore-Baltimore. Heterogeneity of gamma chain of the Hb-F follows the expected pattern. The study provides further evidence that neither beta nor delta chains are synthesized in cis to delta beta-thalassaemia or Hb-Lepore.
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PMID:An individual with Hb-Lepore-Baltimore- delta beta-thalassaemia in a Yugoslavian family. 125 2

We have sequenced the 5' hypersensitive-2 (5'HS-2) site of the locus control region (LCR) and the promoters of the two gamma-globin genes located on chromosome 11 of a black patient with mild beta-thalassemia (beta-thal) major due to a homozygosity for the C----T mutation at position -88 of the beta promoter and with a high Hb F level. Sequence variations in the 5'HS-2 were the same as observed for the beta s chromosome with haplotype number 3, while most of the G gamma promoter and the A gamma promoter had sequences similar to that of the beta S chromosome with haplotype number 19. This atypical haplotype (number 19A) is apparently associated with an increased gamma chain production which is particularly evident during periods of severe hematopoietic stress. Additional studies on relatives of the proband and on 10 unrelated black beta-thal homozygotes with either the C----T mutation at -88 or the A----G mutation at -29, confirm the possible importance of the sequence differences in the 5'HS-2, and also suggest that at least two additional factors, namely a C----T mutation at position -158 of the G gamma promoter and a relative deficiency in alpha chain synthesis play a (perhaps less important) role in the increased Hb F synthesis in these patients.
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PMID:Black beta-thalassemia homozygotes with specific sequence variations in the 5' hypersensitive site-2 of the locus control region have high levels of fetal hemoglobin. 138 15

We report the clinical, hematological, and molecular findings observed in 32 Sicilian patients with sickle cell disease. None of our patients received regular blood transfusions and careful infectious disease prophylaxis was carried out for all. Haplotyping of beta S chromosomes was performed in all patients; all were homozygous for haplotype #19 (Benin). Gene mapping excluded the presence of an alpha-thalassemia in 13 of our patients; none of the relatives showed any evidence of the presence of alpha-thalassemia. Hb F levels were 11.8 +/- 5.9% with G gamma representing 39.6 +/- 3.6% of total gamma chain. Hb F levels were higher in females than in males (12.5 +/- 5.9% versus 9.7 +/- 6.5%) but the difference was not statistically significant. All patients, regardless of age and sex, were anemic with normal mean corpuscular hemoglobin concentration, high mean corpuscular volume and mean corpuscular hemoglobin, and mild reticulocytosis. Analysis of clinical manifestations suggests that our patients have a disease of moderate severity.
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PMID:Clinical, hematological, and molecular features in Sicilians with sickle cell disease. 148 18


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