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)

Complementary DNA (cDNA) specific for gamma-globin nucleotide sequences has been prepared by hybridizing total cDNA made from cord blood messenger RNA (mRNA) as template to an excess of normal adult human globin mRNA and recovering the single-stranded cDNA from hydroxylapatite. The specificity of the gamma cDNA for gamma mRNA sequences is strongly supported by the hybridization of this cDNA at low Cot values (Co, concentration of RNA and t, time in seconds) to RNA samples containing large amounts of functional gamma globin mRNA and the lack of hybridization to RNA samples containing little, if any, gamma-globin mRNA. The absence of cross-hybridization of gamma cDNA with alpha, beta, and delta mRNAs is demonstrated by the complete hybridization of the gamma cDNA to mRNA samples completely lacking either alpha or beta and delta mRNA. An estimate of the number of gamma-globin genes in human cellular DNA was obtained by hybridization of purified gamma cDNA to DNA from spleen and white blood cells of normal and beta-thalassemia subjects and measurement of the percent of gamma cDNA hybridized at saturation. The results indicate that there are between one and two gamma-globin genes per total haploid gene DNA equivalent obtained from both normal and beta-thalassemia subjects. These values are consistent with genetic evidence for the presence of multiple gamma gene loci in human cells. The finding that the number of gamma-globin genes in beta-thalassemia DNA is similar to that in nonthalassemia DNA indicates that a deletion of gamma-globin genes cannot account for either the inadequate gamma-globin synthesis or indirectly for the decreased or absent beta-globin synthesis in beta-thalassemia cells.
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PMID:Quantitation of human gamma globin genes and gamma globin mRNA with purified gamma globin complementary DNA. 99 55

The haemoglobin (Hb) patterns of 345 Shiite Saudi Arab cord bloods were examined by alkaline starch-gel electrophoresis. A fast-moving component, identified by structural analysis as Hb Bart's, was found in 52% of cases, the highest incidence of this variant yet recorded. The levels of Hb Bart's ranged from 0.5 to 16% of the total haemoglobin. The relative rates of synthesis of the alpha, beta and gamma-chains, measured by [3H]leucine incorporation, were estimated in 12 newborn Arab infants. There was an excellent correlation between the amount of Hb Bart's and the alpha/non-alpha-globin-chain production ratio. Furthermore there was a significant correlation between the level of Hb Bart's and morphological abnormalities of the red cells and the mean cell haemoglobin (MCH). These findings indicate that elevated levels of Hb Bart's in this population are due to the presence of alpha thalassaemia. The absence of hydrops fetalis and the rarity of Hb-H disease despite the intense inbreeding in this population, points to an alpha-thalassaemia genotype that is, in terms of phenotypic expression, intermediate between the heterozygous state for alpha-thalassaemia I and Hb-H disease. A possible molecular basis for this genotype is suggested.
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PMID:Haemoglobin Bart's in Saudi Arabia. 123 97

Prenatal diagnoses of the genetic disorders alpha, beta thalassemia, HbS, Hb Lepore, hemophilia and cystic fibrosis were sought in 88 cases. Six unsuccessful attempts at diagnosis resulted from DNA polymorphisms which were only 50% informative (four cases) and prenatal diagnoses which had been undertaken before it was known whether DNA polymorphisms in family studies were informative (two cases). The most frequent indications for prenatal diagnosis were the hemoglobinopathies although requests for exclusion of cystic fibrosis formed the majority during 1989. Strong linkage disequilibrium between the cystic fibrosis defect and its associated DNA polymorphisms facilitated detection of this disorder. Late presentations among patients with beta thalassemia and hemophilia and the necessity for more specialised genetic counselling were the commonest problems encountered.
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PMID:Experience of a molecular genetics service in prenatal diagnosis by DNA analysis. 224 30

A large scale survey of haemoglobinopathies and thalassaemia has been carried out in China, involving 900,000 people in 28 provinces. It has resulted in the finding of many new variants and some interesting cases of thalassaemia, and in a study on the chemical structure of abnormal haemoglobins and DNA analysis of thalassaemia. We report here data on haemoglobin disorders in the Chinese, mainly the characterisation of the geographical distribution of haemoglobin variants, the analysis of globin genes of alpha, beta, gamma, or delta beta thalassaemia, and the progress in prenatal diagnosis of alpha and beta thalassaemia conducted in the authors' laboratory.
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PMID:Disorders of haemoglobin in China. 350 Mar 12

The zeta (zeta) and various gamma (gamma) chains of Hb Portland I have been separated and isolated from blood samples obtained from neonates with hydrops fetalis due to homozygous alpha-thalassemia. By using developers containing acetonitrile, methanol, and potassium phosphate and either an analytical (3.9 mm x 30 cm) or a preparative (7.8 mm x 30 cm) muBondapak C-18 column (Waters), globin chains from 200 micrograms to 5.0 mg have been isolated in pure forms. Analytical and preparative procedures using short (50-min duration) and extended (186-min duration) gradient programs have been developed. In addition to the type of column and developer conditions, the following factors are found to be important: (a) preparation of sample, (b) sample loading, and (c) cleaning of the column. Preliminary studies indicate that the yield ranges from 40 to 60% depending on the type of globin sample and the age of the column. This procedure also permits the separation of alpha, beta, and various gamma globin chains from fetal and adult samples.
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PMID:Separation of zeta (zeta) and various gamma (gamma) chains of human embryonic hemoglobin Portland I by reverse-phase high-performance liquid chromatography. 668 87

Individual human alpha, beta and delta hemoglobin chain types were isolated in a native form so that the hemoglobin tetramers Hb A and Hb A2 could be reconstituted. In order to measure the relative affinity of beta and delta chains for alpha chains, an equimolar mixture of beta and delta chains was incubated with decreasing concentrations of alpha chains. When alpha chains were present in an amount equal to or greater than that of the mixture of beta and delta chains, the amount of Hb A2 was similar to that of Hb A. When alpha chains were in limiting concentrations, more Hb A than A2 was always formed with gradually decreasing amounts of Hb A2. The data as interpreted indicate that alpha chains have an affinity for beta chains at least 7.6-times greater than that for delta chains. These results also suggest that the differential affinity between beta and delta chains may be a major post-translational mechanism, which explains the increased level of Hb A2 in beta-thalassemia, and its reduced amounts in alpha-thalassemia and in acquired disorders with deficient alpha-chain synthesis.
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PMID:Differences in affinity of beta and delta hemoglobin chains for alpha chains. A possible explanation for the variation in the percentages of hemoglobin A2 in thalassemia and other disorders. 682 3

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

A 21-year-old American black female with mild anemia was found to be triply heterozygous for alpha-thalassemia-2, hemoglobin S and hemoglobin G Philadelphia. Hemoglobin A comprised 39% of her total hemoglobin. The alpha-thalassemia gene was expressed by an alpha/non-alpha synthesis of ratio of 0.79 +/- 0.09 and was equally unbalanced in the peripheral blood and the bone marrow. Globin synthesis studies indicated that the percentage of Hb G and Hb S in the peripheral blood is about 32% and 31% respectively. These values are due to the coexistent alpha-thalassemia-2 gene with the following most likely genotype: --alpha G/alpha alpha, beta A/beta S (or --alpha/alpha G alpha, beta A beta S).
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PMID:Globin synthesis studies in a person heterozygous for alpha-thalassemia-2, Hb S and Hb G Philadelphia. 735 Oct 73

Reversed-phase high pressure liquid chromatography (HPLC) was used for the separation of the alpha, beta, (A)gamma and (G)gamma chains from human blood samples. The alpha and beta chains were normally eluted close together, but their separation was improved by coupling 2 or 3 columns in series, or by increasing the temperature of the columns. This method has been applied for the determination of beta/gamma ratios in blood samples obtained at fetoscopy from normal pregnancies and fetuses at risk for beta-thalassemia. The values obtained by high pressure chromatography were similar but slightly lower than those found by carboxymethyl cellulose (CMC) chromatography. The average (G)gamma/(A)gamma ratio of the chains labeled after a 2-hr pulse with [3H] leucine was almost identical to the actual (G)gamma/(A)gamma measured by absorbance at 280 nm, indicating a constant rate of synthesis and accumulation of both globin chains in the first trimester fetus.
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PMID:Rapid procedure for globin chain analysis in blood samples of normal and beta-thalassemic fetuses. 744 29

In this study, we have defined by molecular analysis, the alpha, beta, and delta globin genotype in a group of individuals with normal or thal-like red cell indices but borderline hemoglobin (Hb)A2 levels, who were identified in a program for beta-thal carrier screening. In 37 of 125 individuals with borderline HbA2 levels, we detected a molecular defect in the beta, in both the delta and the beta, or in the alpha globin gene. Specifically seven of these subjects were carriers of the -101 C T mutation, ten of the IVSI nt6 T C mutation, 16 were double heterozygotes for delta and beta thal, and two had the triple alpha globin gene and two the single alpha globin gene deletion. From these results, we may conclude that subjects with borderline HbA2, particularly when they marry a typical beta-thal carrier, should be extensively investigated in order not to miss heterozygous beta-thalassemia.
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PMID:Genotype of subjects with borderline hemoglobin A2 levels: implication for beta-thalassemia carrier screening. 817 99


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