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)

Hemoglobin Crete, beta129 (h7)ala leads to pro, is a new mutant hemoglobin (Hb) with high oxygen affinity that was discovered in a Greek family in various combinations with beta- and deltabeta-thalassemia. The propositus, who presented an unusual clinical picture of an "overcompensated" hemolytic state, with erythrocytosis, splenomegaly, abnormal red cell morphology, and marked erythroid hyperplasia, appeared doubly heterozygous for Hb Crete and deltabeta-thalassemia. His red cells contained 67% Hb Crete and 30% Hb F, and the combination of these two hemoglobins resulted in a blood P50O2 of 11.2 mm Hg. A brother with Hb Crete trait (38% Hb Crete, 56% Hb A, blood P50O2 23.0 mm Hg) did not have significant erythrocytosis. Purified Hb Crete was heat-unstable and exhibited a high oxygen affinity, and a normal Bohr effect. We postulate that the beta 129 proline substitution disrupts the H helix, perturbing nearby residues involved in alpha 1 beta 1 contact sites of the Hb tetramer.
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PMID:Hemoglobin Crete (beta 129 ala leads to pro): a new high-affinity variant interacting with beta o -and delta beta o -thalassemia. 3 84

This study describes a patient with a thalassemia intermedia-like phenotype in whom beta-globin gene sequencing detected a novel abnormal hemoglobin (Hb) due to a T-C substitution at codon 114 of the beta-globin gene arising as a de novo mutation. The abnormal variant was designated Hb Brescia after the place of birth of the propositus. Normal sequences were detected at the in trans beta-globin locus. In addition, alpha-globin gene analysis detected a triple alpha-globin locus which was inherited from the father. The T-C change at position 114 of the beta-globin gene results in a leucine to proline substitution (Leu-Pro) in the G-helix. The resulting Hb tetramer is highly unstable and precipitates forming inclusion bodies in the peripheral red blood cells. Moreover, the Leu-Pro substitution interferes negatively with the four alpha 1 beta 1 contact points of the G-helix most likely adversely affecting the alpha beta dimer formation. The very severe phenotype presented by our patient is unusual in a heterozygote for an unstable Hb variant and may be explained by the coinheritance of the triple alpha-globin locus.
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PMID:A novel beta-globin structural mutant, Hb Brescia (beta 114 Leu-Pro), causing a severe beta-thalassemia intermedia phenotype. 130 Nov 99

The molecular basis of most beta-thalassemia syndromes has been defined, while the spectrum of mutations causing delta-thalassemia is not well characterized. In an attempt to identify such mutations, the region encompassing the delta-globin gene from three Greek Cypriot families suspected of having delta-thalassemia was amplified by polymerase chain reaction (PCR), and DNA sequence determined using an automated fluorescence-based sequencer. Four novel mutations were identified: a G----T change at codon 27 that results in an alanine to serine change; a C----T change at codon 116 converting arginine to cysteine; a T----C change at codon 141 converting leucine to proline; and an AG----GG change at the consensus 3'-acceptor site in IVS-2. While the latter is clearly a thalassemic mutation, the low hemoglobin A2 in the first three may be due to either decreased production or instability of the altered delta-globin chain. All four mutations may be detected by PCR amplification of genomic DNA followed by restriction enzyme digestion. Two mutations abolish restriction sites while two create new cleavage sites. Screening for molecular defects that cause delta-thalassemia or unstable delta-globin by PCR amplification and restriction enzyme digestion will lead to correct diagnosis of beta/delta-thalassemia compound heterozygotes and improved genetic counseling.
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PMID:Identification of four novel delta-globin gene mutations in Greek Cypriots using polymerase chain reaction and automated fluorescence-based DNA sequence analysis. 174 90

Molecular analysis of the beta-globin genes from a patient with a beta-thalassemia phenotype showed that a single nucleotide mutation (CTG-CCG) at codon 110 in one of the genes resulted in a leucine to proline substitution. The same mutation with a similar phenotype, was observed in her mother and sister, by Southern blotting analysis of DNAs digested with Mspl, the recognition site of which was created by this base substitution. This indicates a close relationship between this mutation and the beta-thalassemia phenotype. No anomalous peak of radioactivity was detected by reverse-phase high-performance liquid chromatography (HPLC) in the patient's reticulocytes incubated with isotopically labeled amino acid. The leucine-proline (Leu-Pro) substitution probably disrupts the G-helix and in turn interferes with globin contact points. The uncombined beta-globin chain would be rapidly destroyed and the beta-thalassemia phenotype would follow.
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PMID:A novel globin structural mutant, Showa-Yakushiji (beta 110 Leu-Pro) causing a beta-thalassemia phenotype. 282 77

We have described a novel human globin gene mutation that produced in a Japanese family the beta-thalassemia phenotype through a post-translational mechanism. Substitution of proline for leucine at position 110 in the G-helix of the beta-globin chain greatly reduced the molecular stability of the beta-globin subunit, leading to total destruction of the variant globin chains by proteolysis and hence to the beta-thalassemia phenotype. The mutation could be identified after MspI digestion. This detection of the mutation on the gene level is valuable for diagnostic purposes.
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PMID:A substitution of cytosine for thymine in codon 110 of the human beta-globin gene is a novel cause of beta-thalassemia phenotypes. 341

In a previous study, molecular cloning of the alpha-globin genes from a patient with nondeletion Hb-H disease (genotype--/alpha alpha) showed that a single nucleotide mutation (CTG to CCG) in one of the genes resulted in a leucine to proline substitution. This paper describes the approach we used to detect the abnormal alpha-globin chain. The chain was identified using a cell-free translation system. It turned over rapidly both in vitro and in vivo in the patient's reticulocytes. The unusual feature of this unstable alpha-globin is that the alpha-globin deficiency causes alpha-thalassemia. Simple heterozygotes for this lesion (alpha Pro alpha/alpha alpha) resemble alpha-thalassemia carriers and do not exhibit the hemolytic anemia usually associated with unstable hemoglobins.
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PMID:alpha-Thalassemia caused by an unstable alpha-globin mutant. 682 18

A 67-year-old woman with pulmonary embolism was suspected to have beta-thalassemia based on microcytosis, hemolysis and a negative red cell stability test. The DNA sequencing analysis of beta-globin gene, however, revealed the deletion of three nucleotides within codon 127-128, leading to substitution of glutamine and alanine residues at 127 and 128 by proline, namely Hb Gunma. This mutant is characterized by the fact that no abnormal hemoglobin is detected in the circulating blood, and is classified as a thalassemic hemoglobinopathy. The present case showed a relatively hemolytic manifestation.
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PMID:Hb Gunma (beta Gunma) with pulmonary embolism. 764 5

A recently initiated collaboration between Russian and American institutions has resulted in the characterization of several known or new beta-thalassemia alleles and unstable hemoglobin types. Nine known beta-thalassemia alleles were present which have also been found in Mediterranean, East Asian, and Black populations; the possibility of independent mutations for some of the rare alleles should be considered. Hb Durham-N.C./Brescia with a codon 114 (CTG-->CCG; Leu-->Pro) change was present in six members of two families. This condition and two new variants have the characteristics of a dominant type of beta-thalassemia heterozygosity with moderate anemia, Heinz body formation, splenomegaly, etc. One new beta-thalassemia allele is a frame-shift at codon 124 (-A), while another is characterized by the introduction of an extra proline residue (codon: CCA) between residues Thr (beta 123) and Val (beta 126) to give the sequence -Thr-Pro-Pro-Pro-Val-.
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PMID:Beta-thalassemia alleles and unstable hemoglobin types among Russian pediatric patients. 803 85

Mutations within exon 3 of the beta-globin gene are relatively uncommon, and many of these mutations produce a dominant thalassemia-like phenotype. We describe a novel thalassemic hemoglobinopathy caused by a single nucleotide substitution (CTG-->CCG) at codon 114 resulting in a leucine to proline substitution and designate it beta Durham-NC [beta 114 Leu-->Pro]. The mutation producing this thalassemic hemoglobinopathy is located near to the beta Showa-Yakushiji mutation (beta 110 Leu-->Pro). Both of these hemoglobinopathies share similar phenotypic features with moderately severe microcytic anemia. Using computer imaging of the hemoglobin molecule, we examined several reported point mutations within exon 3 of the beta-globin gene. These point mutations cause a single amino acid substitution in the G helix, and result in a thalassemic and/or hemolytic phenotype. Computer imaging of nine separate examples suggests that amino acid substitutions affecting side chains that project into the heme pocket may destabilize the heme moiety within the beta-globin chain, resulting in a thalassemic phenotype. Hemolytic phenotypes may be the result of decreased alpha 1 beta 1 interactions. The beta Durham-NC mutation further characterizes a novel group of thalassemias/hemoglobinopathies that are clinically difficult to identify and require accessory laboratory testing.
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PMID:A novel beta-globin mutation, beta Durham-NC [beta 114 Leu-->Pro], produces a dominant thalassemia-like phenotype. 811 Oct 50

We have identified three individuals of Greek or Greek Cypriot origin with an atypical form of HbH disease characterized by a severe hypochromic microcytic anaemia associated with relatively small amounts of HbH in the peripheral blood. Molecular analysis has shown that each is a compound heterozygote for a previously described mutation affecting the poly A addition signal (AATAAA-->AATAAG) and a previously undescribed mutation involving a T-->C transition in codon 29 of the alpha 2 gene causing a leucine-->proline substitution. Although this mutation would be expected to produce an unstable haemoglobin and hence a haemolytic anaemia, simple heterozygotes for the alpha 29Leu-->Pro mutation have the phenotype of alpha-thalassaemia trait.
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PMID:A base substitution (T-->C) in codon 29 of the alpha 2-globin gene causes alpha thalassaemia. 813 77


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