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)

We have analyzed the hemoglobins of a young German patient with beta-thalassemia intermedia and of his immediate family and included in these studies an evaluation of possible nucleotide changes in the beta-globin genes through sequencing of amplified DNA. One chromosome of the propositus and one of his father's carried the GTG-->GGG mutation at codon 126 leading to the synthesis of Hb Dhonburi or alpha 2 beta (2)126(H4)Val-->Gly; this variant is slightly unstable and is associated with mild thalassemic features. His second chromosome and one of his mother's had the common IVS-I-5 (G-->C) mutation that leads to a rather severe beta(+)-thalassemia and the GTG-->ATG mutation at codon 18, resulting in the replacement of a valine residue by a methionine residue. This newly discovered beta-chain variant, named Hb Baden, was present for only 2-3% in both the patient and his mother. This low amount results from a decreased splicing of RNA at the donor splice-site of the first intron that is nearly completely deactivated by the IVS-I-5 (G-->C) thalassemic mutation. The chromosome with the codon 18 (GTG-->ATG) and the IVS-I-5 (G-->C) mutations has thus far been found only in this German family; analysis of 51 chromosomes from patients with the IVS-I-5 (G-->C) mutation living in different countries failed to detect the codon 18 (GTG-->ATG) change.
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PMID:Heterozygosity for the IVS-I-5 (G-->C) mutation with a G-->A change at codon 18 (Val-->Met; Hb Baden) in cis and a T-->G mutation at codon 126 (Val-->Gly; Hb Dhonburi) in trans resulting in a thalassemia intermedia. 146 68

A rapid, simple, cost-effective, non-radioactive method for detection of the most common mutations causing beta-thalassemia in Mediterranean people has been developed by combining multiplexing with the amplification refractory system. This approach, the multiplex amplification refractory mutation system (MARMS), provides an easy assay for direct detection of normal and mutant beta-globin genes in homozygotes and heterozygotes. The strategy involves multiplex PCR of four of the five regions of interest within the beta-globin gene in a single reaction containing a common oligoprimer and either the normal or mutant oligonucleotides corresponding to IVS-1 nucleotide 1 or IVS-1 nucleotide 6, IVS-1 nucleotide 110, codon 39, and IVS-2 nucleotide 1 regions. Primers are chosen so that the sizes of the four PCR products differ, thereby facilitating detection on agarose gels following amplification. Patient samples are primed with either four normal or four mutant oligonucleotide mixtures and the common oligoprimer, and PCR products run in parallel on gels to detect band presence or absence. This approach simplifies mutation detection and shows promise for automation employing fluorescent-tagged primers.
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PMID:Detection of the most common mutations causing beta-thalassemia in Mediterraneans using a multiplex amplification refractory mutation system (MARMS). 147 72

A family of Asian-Indian descent has a variant form of beta-thalassaemia characterized by unusually high levels of Hb A2 in the heterozygous state. The propositus who is homozygous for the mutation has thalassaemia intermedia. Restriction endonuclease mapping suggested the presence of a 10.3 kilobase (kb) deletion removing the whole of the beta-globin gene. Subsequently, molecular analysis was performed by directly sequencing a specifically amplified region of genomic DNA. A 10329 basepair deletion was precisely defined which results in the loss of the 5' beta promoter region and the entire beta-globin gene. The deletion extends from 3011 bp 5' to the mRNA cap site to an L1 repeat element downstream of the beta-globin gene and is very similar to the 12.6 kb deletion of Dutch beta zero-thalassaemia. In common with four other mutations, both these deletions remove the 5' promoter region of the beta gene and all are associated with unusually elevated levels of Hb A2 in the heterozygous state.
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PMID:Molecular characterization of a novel 10.3 kb deletion causing beta-thalassaemia with unusually high Hb A2. 148 61

We have analysed the molecular basis of beta-thalassaemia in 22 Anglo-Saxon individuals, all of whom were heterozygous for beta-thalassaemia except for one, who was a compound heterozygote. Using a combination of allele-specific priming of the polymerase chain reaction (PCR) and direct sequencing of genomic DNA amplified by the PCR, 20/23 beta-thalassaemic genes were characterized. Nine different mutations were identified; four are commonly found in the Mediterranean, one in Asia, one has been described previously in both Europe and Asia, and three are rare mutations associated with a dominant beta-thalassaemia phenotype. In three individuals the mutation remains uncharacterized despite sequence analysis of the beta-globin gene and its immediate flanking regions. We report our findings and discuss the diversity of these mutations.
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PMID:Beta thalassaemia in the indigenous British population. 148 39

This paper reports our experience of molecular screening and fetal diagnosis of beta-thalassemia in 457 at risk couples of Italian descent. Molecular screening was carried out by dot blot analysis on amplified DNA with oligonucleotide probes complementary to the eight most common mutations in Italians [beta zero 39 (C----T); beta zero 6 (-A); beta+ -87 (C----G); beta+ IVSI nt 110 (G----A); beta zero IVSI nt 1 (G----A); beta+ IVSI nt 6 (T----C); beta zero IVSII nt 1 (G----A); beta+ IVSII nt 745 (C----G)]. By using this approach, we have been able to define the mutation in 92.8% of cases. The rest (all but four) were defined by direct sequencing and this led to the detection of nine rare mutations [beta zero 76 (-C); beta+ IVSI nt 5 (G----A); beta+ IVSI nt 5 (G----C); beta+ IVSI -1 (cod 30) (G----C); beta+ -87 (C----T), beta zero -290 bp del.; beta+ -101 (C----T)], and to the characterization of a novel mutation consisting of the deletion of the G at the invariant AG of the IVSII splice acceptor site of the beta-globin gene (beta IVSII nt 850 -1 bp). In the remaining four cases, the beta-globin gene showed entirely normal sequences and the beta-globin gene cluster was intact, as indicated by Southern blot analysis. Fetal diagnosis was carried out by dot blot analysis with the oligonucleotide probes defined in the parents. The procedure is simple and reliable, and the results can be obtained within 1 week of sampling. No misdiagnosis has so far occurred. The results indicate that fetal diagnosis of beta-thalassemia by DNA analysis may be obtained in practically all cases (even in a population showing marked heterogeneity of beta-thalassemia) by the combination of dot blot analysis for detecting common mutations, and direct sequencing for defining those that are uncommon.
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PMID:Molecular screening and fetal diagnosis of beta-thalassemia in the Italian population. 151 73

6 out of 14 uncharacterized beta-thalassemia alleles from 187 Thai beta-thalassemia/HbE patients were identified by direct sequencing of DNA amplified by polymerase chain reaction. A novel mutation occurring from an insertion of adenosine in codon 95, which results in a shift of the reading frame with terminator at the new codon 101, was detected in one patient. In addition, two frameshift mutations not previously reported among the Thai population were also detected in 3 patients: one with a deletion of thymidine in codon 15 and two with an insertion of cytidine in codons 27/28. A frameshift mutation that occurred from a cytidine deletion in codon 41 was also found in one patient in this study. The remaining case was an amber mutation, GAG-TAG, in codon 43 in exon 2 of the beta-globin gene. These mutations bring the number of mutations known to be present in the Thai population to a total of 20, 15 of which were detected in beta-thalassemia/HbE patients.
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PMID:Identification of five rare mutations including a novel frameshift mutation causing beta zero-thalassemia in Thai patients with beta zero-thalassemia/hemoglobin E disease. 151 53

Two novel beta-thalassemia mutations are described. The first mutation, found in an Italian family, is a G----A substitution in nucleotide (nt) +22 relative to the beta-globin gene Cap site. This mutation creates a cryptic ATG initiation codon, the utilization of which for translation would result in premature termination 36 bp 3' downstream. The second mutation, found in an Irish family, is a T----C substitution in nt +1570, or 12 bp 5' upstream of the AATAAA polyadenylation signal in the 3' noncoding region. It is postulated that this mutation leads to destabilization of the encoded beta-globin mRNA.
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PMID:Two novel beta-thalassemia mutations in the 5' and 3' noncoding regions of the beta-globin gene. 151 49

We have previously shown that excess unpaired alpha- and beta-globin chains in severe alpha- and beta-thalassemia interacting with the membrane skeleton induce different changes in membrane properties of red blood cells (RBCs) in these two phenotypes. We suggest that these differences in membrane material behavior may reflect the specificity of the membrane damage induced by alpha- and beta-globin chains. To further explore this hypothesis, we sought in vitro models that induce similar membrane alterations in normal RBCs. We found that treatment of normal RBCs with phenylhydrazine produced rigid and mechanically unstable membranes in conjunction with selective association of oxidized alpha-globin chains with the membrane skeleton, features characteristic of RBCs in severe beta-thalassemia. Methylhydrazine, in contrast, induced selective association of oxidized beta-globin chains with the membrane skeleton and produced rigid but hyperstable membranes, features that mimicked those of RBCs in severe alpha-thalassemia. These findings suggest that consequences of oxidation induced by globin chains are quite specific in that those agents that cause alpha-globin chain accumulation at the membrane produce rigid but mechanically unstable membranes, whereas membrane accumulation of beta-globin chains results in rigid but mechanically stable membranes. These in vitro experiments lend further support to the hypothesis that membrane-associated alpha- and beta-chains induce oxidative damage to highly specific different skeletal components and that the specificity of this skeletal damage accounts for the differences in material membrane properties of these oxidatively attacked RBCs and perhaps of alpha- and beta-thalassemic RBCs as well.
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PMID:Globin-chain specificity of oxidation-induced changes in red blood cell membrane properties. 154 47

In this study we have investigated the molecular basis for a mild form of beta-thalassaemia in three patients of Italian descent. In two, belonging to different families and affected by a mild and late-presenting form of thalassaemia major, direct sequencing of amplified DNA detected a C----T substitution at position -87 of the beta-globin gene in the compound heterozygous state either with codon 39 nonsense mutation or beta +IVSI, nt 110 mutation. The -87 (C----T) mutation has been previously described, in combination with the beta +IVSI, nt 110 mutation, in a single patient with thalassaemia intermedia. Both our patients showed a more severe phenotype as compared to that resulting from compound heterozygosity for a severe beta-thalassaemia mutation and another promoter mutation (-87, C----G) at the same position. In the third patient with the thalassaemia intermedia phenotype, we detected a novel promoter mutation, consisting in a C----A substitution at position -86, in combination with the codon 39 nonsense mutation. The results of this study indicate that different nucleotide substitutions affecting the proximal CACCC box of the beta-globin gene in combination with severe beta-thalassaemia, produce a mild form of thalassaemia ranging in severity from thalassaemia intermedia to late-presenting thalassaemia major.
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PMID:Promoter mutations producing mild beta-thalassaemia in the Italian population. 155 Jul 80

A common mutation causing thalassemia in Mediterranean populations is an amber (UAG) nonsense mutation at the 39th codon of the human beta-globin gene, the beta-39 mutation. Studies of mRNA metabolism in erythroblasts from patients with beta-39 thalassemia and studies using heterologous transfection systems have suggested the possibility that this mutation not only affects protein synthesis but also alters mRNA metabolism. The effects of this mutation on several steps in the metabolism of mRNA have been investigated by transfection of the gene into permanent cell lines bearing a temperature-sensitive RNA polymerase II. Several RNA expression studies were performed, including analysis of transcription, mRNA stability, mRNA splicing accuracy, and mRNA polyadenylation. The results suggest that the defect in expression of the beta-39 mRNA occurs at a step prior to the accumulation of mRNA in the cytoplasm.
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PMID:Beta-globin nonsense mutation: deficient accumulation of mRNA occurs despite normal cytoplasmic stability. 155 99


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