Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THALASSEMIA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82Linked to original sources
PubMed1989

Alpha-thalassemia changes the cell density profile in sickle cell anaemia.

Several factors are implied in the haematological and clinical picture of sickle cell anaemia. Attention has been focused on the concomitant presence of -alpha-thalassemia and high levels of HbF, but contradictory results have been reported in different populations. We compared the blood cell density profile, obtained by the phtalate esther method, of normal subjects with those of patients with sickle cell anaemia - with or without heterozygous alpha-thalassemia. We found that the density profile of both groups of patients differs from normal subjects, and that a difference can also be demonstrated between normal alpha genotype patients with sickle cell anaemia and patients with heterozygous alpha-thalassemia. These results are in agreement with the findings obtained in other countries in which a gene from Caucasian to African populations have been demonstrated, and are different from the results obtained in populations of more pure African ancestry. It can be suggested, therefore, that these data, in addition with findings of other authors in different geographical areas, support the hypothesis that the genetic make up plays an important role in the haematologic and clinical picture of sickle cell anaemia.

Anemia, Sickle Cell↗
PubMed1989

The prevention of thalassemia in Sardinia.

In this paper we review the characteristics and effectiveness of a program aimed at preventing homozygous beta-thalassemia in the Sardinian population. The target population for screening were couples at marriage, conception or early pregnancy. Awareness of the problem and the involvement of the population were achieved via the mass media or by personal approaches through lectures or discussions. Parents' Associations were consulted and have made themselves available to prospective couples in several critical areas. Education on thalassemias was introduced into the school curriculum. Counseling was based on private interviews at which the several options available were discussed with the individual carrier or the couples. Prenatal diagnosis was chosen by the large majority of couples counseled. The introduction of 1st trimester diagnosis resulted in a striking increase of the acceptance rate from 93.2 to 99.1%. Prenatal diagnosis was carried out initially by fetal blood analysis and thereafter by trophoblast or amniocyte DNA analysis. Direct detection of the mutation by oligonucleotide hybridization on agarose gel separated DNA fragments or by dot-blot analysis with allelic specific oligonucleotide probes on enzymatically amplified DNA was used. This program resulted in a decline in thalassemia major births of 90%. The reasons for residual cases were mostly lack of information and, less frequently, misdiagnoses or refusal of fetal diagnosis.

Adult↗
PubMed1989

Analysis of hematological data of thalassemia cases in Thailand.

We analyzed the complete blood count (CBC) obtained from patients with various types of thalassemia in Thailand. As a control, samples from healthy donors and patients with iron deficiency anemia were also collected. Most cases of thalassemia could be differentiated from iron deficiency anemia by using a discrimination function equation. This screening method is applicable for mass-screening of patients with latent thalassemia in Thailand.

Erythrocyte Count↗
PubMed1989

The performance characteristics of an expert system for the "on-line" assessment of thalassemia trait and iron deficiency--Micro Hema Screen.

An Expert System (ES) approach to the assessment of thalassemia trait and iron deficiency was evaluated by transferring data from a Coulter S-Plus II Analyzer to an Apple II e computer. The discriminant rules of the algorithm were derived retrospectively from multivariate analysis of an existing data base. The parameters used were MCV, RDW, HGB, RBC, MPV, and PLT. Subsequently, the system has been evaluated for its ability to detect thalassemia and hemoglobinophathies in 1671 females and 1490 males in a real laboratory setting. The 845 cases of microcytosis among them were used to estimate the real frequencies of the diagnostic groups as identified by the ES (Micro Hema Screen). "On-Line" assessment of microcytosis may provide a quick method of acquiring and processing the data from an automated analyser. It can be applied in thalassemia and iron deficiency discrimination either as an intralaboratory primary assessment or as a population screening method.

Adolescent↗
PubMed1989

[Yersinia enterocolitica infections and thalassemia major in children].

We report two cases of severe Yersinia enterocolitica infection in children with homozygous thalassemia. One patient had septicemia and the other had mesenteric adenitis. Two factors can enhance the infectivity of Yersinia enterocolitica in children with thalassemia: iron overload and deferoxamine therapy. Laparotomy and cefotaxime-netilmicin therapy were successful in the patient with mesenteric adenitis. In the patient with septicemia, cefotaxime-netilmicin, then doxycycline-netilmicin failed, and recovery was finally achieved under rifampicin-netilmicin. Because of the possibility of septicemic dissemination secondary to digestive Yersinia enterocolitica infection in children with thalassemia, we advocate immediate discontinuation of deferoxamine and prescription of oral antimicrobial therapy (trimethoprim-sulfamethoxazole for instance) in every thalassemic patient with febrile diarrhea.

Adolescent↗
PubMed1989

Hemoglobin Köln occurring in association with a beta zero thalassemia: hematologic and functional consequences.

Hemoglobin (Hb) Köln-beta zero thalassemia compound heterozygosity was discovered in a young Greek patient. This gave us the unique opportunity for studying the functional properties of this unstable high-oxygen affinity hemoglobin variant in red cells containing almost pure Hb Köln. The red cells of the proposita exhibit morphological alterations and hematologic indices corresponding to the presence of an unstable Hb and beta thalassemia. Globin chain synthesis confirmed the association with a beta zero thalassemia gene. Oxygen-binding curves for these cells were biphasic, indicating the presence of both heme-saturated and of approximately 20% of non-cooperative Hb Köln. The major component exhibits an increased oxygen affinity, reduced cooperativeness, and normal alkaline Bohr effect. The 35-year-old proposita is active, has not been splenectomized, and has not been transfused in several years.

Adult↗
PubMed1987

A novel globin structural mutant, Showa-Yakushiji (beta 110 Leu-Pro) causing a beta-thalassemia phenotype.

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.

Amino Acid Sequence↗
PubMed1988

The Corfu delta beta zero thalassemia: a small deletion acts at a distance to selectively abolish beta globin gene expression.

The Corfu delta beta zero thalassemia is characterized by the clinical picture of thalassemia intermedia. In the homozygous state there is a complete absence of hemoglobin (Hb) A and Hb A2 and a high level of Hb F. A DNA fragment containing the gamma and beta globin genes has been cosmid cloned, and the deletion breakpoint region, the beta globin gene and the promoter regions of the gamma globin genes sequenced. The deletion removes 7,201 base pairs (bp) containing part of the delta globin gene and sequences upstream. The beta globin gene contains a G----A mutation at IVS 1 position 5. The gamma globin gene promoters are normal. Analysis of the transcription of the mutated beta globin gene in transfected HeLa cells shows that normal message is produced at a level of approximately 20% compared with a normal gene, the remaining 80% being spliced at cryptic sites in exon 1 and intron 1. This indicates that the mutation in the beta globin gene is not the sole cause of the absence of Hb A in Corfu delta beta zero thalassemia. It is concluded that the 7.2 kilobase (kb) of deleted DNA contains sequences necessary for the normal activation of the beta globin gene. Possible mechanisms for the effect of the deletion on the expression of beta and gamma globin genes are discussed.

Base Sequence↗
PubMed1988

Beta thalassemia in Melanesia: association with malaria and characterization of a common variant (IVS-1 nt 5 G----C).

Data on the distribution of beta thalassemia among over 6,000 Melanesians reveals a major difference in the carrier rates between populations in the malarious coastal regions of New Guinea and those living in the historically malaria-free Highlands. The island of Maewo in Vanuatu has a particularly high incidence of beta + thalassemia associated with a single restriction enzyme haplotype. Direct cloning into a plasmid vector and sequence analysis demonstrate that the mutation is a G to C transversion at position 5 of intron 1 of the beta-globin gene. Oligonucleotide probe surveys indicate that this variant accounted for all cases of beta thalassemia studied from Maewo. It is also common in coastal Papua New Guinea where haplotype and oligonucleotide probe data suggest that the molecular basis of beta thalassmia is more heterogeneous.

Alleles↗
PubMed1986

Decreased natural killer activity in thalassemia major: a possible consequence of iron overload.

We have investigated the natural killer (NK) activity of both fractionated (Percoll density gradient) and unfractionated mononuclear cells from patients with beta-thalassemia major who are iron overloaded as a consequence of chronic transfusion therapy. These patients were found to have significantly decreased NK activity against K562 targets at all effector:target ratios tested (p less than 0.001). Both splenectomized and nonsplenectomized patients had normal proportions of Leu-11b-staining (NK) cells. Since they had normal to elevated absolute white cell and lymphocyte counts, a change in the absolute number of NK cells could not account for the decreased killing. We also found that the decrease in NK activity was transfusion related (r = -0.603, p less than 0.005). To determine whether or not this decrease in NK activity could be related to iron overload, we preincubated patient effector cells with desferrioxamine (DFO) or 2,3-dihydroxybenzoic acid (DHB) for 6 hr before addition of K562 targets. Both of these iron-chelating agents consistently increased the NK activity of cells from thalassemia patients. DHB had the greater effect, being able to increase patient NK activity to virtually normal levels. On the other hand, preincubation of cells from normal controls with DHB caused only a slight increase in NK activity, while similar treatment with DFO had little or no effect. When target cells were preincubated with the chelating agents before addition of either normal or patient effector cells, no change in cytotoxicity was seen, demonstrating that the chelating agents act at the effector cell level. Furthermore, if the chelating agents were saturated with iron prior to preincubation with the effectors, no increase in the cytotoxicity of thalassemic NK cells was observed. These results indicate that thalassemia patients have a reversible, transfusion-related decrease in NK function which may arise as a consequence of iron overload.

Cell Separation↗
PubMed1986

Characterization of a spontaneous mutation to a beta-thalassemia allele.

We have studied a nuclear family containing a single child with severe beta-thalassemia intermedia, a Greek-Cypriot mother with hematological findings of beta-thalassemia trait, and a Polish father who is hematologically normal. Since both the child and her father were heterozygous for a DNA polymorphism within the beta-globin gene, it was possible to clone and sequence the beta-globin gene identical by descent from both the child and her father. A nonsense mutation in codon 121 (GAA----TAA) was found in the beta-globin gene of the child, while the same gene from her father lacked this mutation and was normal. This mutation has not been previously observed among over 200 beta-thalassemia genes characterized in Caucasians. Since the mutation eliminates an EcoRI site in the beta-globin gene, we could show that the mutation is not present in genomic DNA of the father. To rule out germinal mosaicism, sperm DNA of the father was also digested with EcoRI, and the mutant EcoRI fragment was not observed under conditions that would detect the mutation if it were present in at least 2% of sperm cells. Routine HLA and blood group testing supported stated paternity. In addition, studies with 17 DNA probes that detect multiple allele polymorphisms increased the probability of stated paternity to at least 10(8):1. These data provide evidence that the G----T change in codon 121 of the beta-globin gene in the child is the result of a spontaneous mutation that occurred during spermatogenesis in a paternal germ cell.

Alleles↗
PubMed1988

A novel monoclonal antibody based diagnostic test for alpha-thalassemia-1 carriers due to the (-SEA/) deletion.

The presence of minute amounts of embryonic zeta-globin chains in adult hemolysates is a marker for carriers of alpha-thalassemia-1 resulting from (--SEA/) deletion. Recently, we developed a murine monoclonal antihuman embryonic zeta-globin chain antibody, 8E8. By using this antibody, we have now established a slot-blot immunobinding assay for the rapid detection of zeta-globin chains in adult hemolysates. zeta-globin chains were found to be present in 30 blood samples obtained from individuals who were carriers of alpha-thalassemia-1. In another 30 blood samples from individuals who were not carriers of the (--SEA/) deletion, zeta-globin chains were not detected. This simple diagnostic test can be used in appropriate populations to identify those couples at risk of conceiving fetuses afflicted with the Hb Bart's hydrops fetalis syndrome due to homozygous alpha-thalassemia.

Antibodies, Monoclonal↗
PubMed1987

Heterogeneity and origins of the alpha-thalassemias.

The alpha-globin gene cluster is far from static. It shows remarkable diversity within and among populations, both in gene number and in the pattern of polymorphisms involving the hypervariable regions. The deletions that have given rise to alpha(0)-thalassemia appear to have resulted from rare genetic events, and the affected chromosomes have been distributed among localized populations by selection. On the other hand, the deletions that have given rise to at least one of the alpha(+)-thalassemias seem to have occurred on multiple occasions in different populations. The genesis of this condition, the most common single gene disorder, may reflect the concerted evolution of the alpha-globin genes, and the alpha(+)-thalassemias may have arisen as a by-product of this evolutionary process. The existence of such a polymorphic gene family and the fact that its mutations are the most common single gene disorders in man provide us with a remarkable, natural model for studying population genetics at the molecular level. Further analysis of this cluster may provide valuable information about the timing of racial diversions, population movements, and the molecular events that have helped to maintain such high gene frequencies for some of the mutations of these loci.

Biological Evolution↗
PubMed1987

Right ventricular cardiac dysfunction in beta-thalassemia major.

In patients with iron overload associated with severe, transfusion-dependent beta-thalassemia, congestive heart failure develops during the second decade of life. Biventricular heart function was studied by multigated radionuclide angiography in 22 patients with beta-thalassemia major. Six patients were symptomatic. Congestive heart failure developed in five patients at the time of blood transfusions, and one other patient had been treated for multiple ventricular extrasystole. The mean (+/- SD) left ventricular ejection fraction was normal (63.0% +/- 7.6%). Only one patient had a left ventricular ejection fraction under the normal level (less than 50%). The mean (+/- SD) right ventricular fraction (RVEF) was 33.3% +/- 9.4%. In only three patients was the RVEF normal (greater than or equal to 40%); an RVEF under 30% was registered in six patients. We suggest that the early right ventricular dysfunction in patients with beta-thalassemia may be due to pulmonary hypertension secondary to iron overload and iron deposits in the ventricles.

Adolescent↗
PubMed1986

Molecular characterization of an atypical beta-thalassemia caused by a large deletion in the 5' beta-globin gene region.

We describe a Canadian family of Czechoslovakian descent that came to our attention because of an HbA2 percentage approximately twice that of an average case of heterozygous beta-thalassemia. This unique phenotype suggested to us the possibility of a novel genetic mechanism being responsible for their beta-thalassemia. To investigate this possibility, we mapped, cloned, and sequenced the mutant beta-globin allele. This molecular analysis demonstrated the presence of a unique 4,237 base pair (bp) deletion extending from 3.3 kilobases (kb) 5' of the beta-globin mRNA cap site to approximately the middle of beta IVS-2. This truncated beta-globin gene further extends the heterogeneity of mutations known to cause beta-thalassemia and delineates new sequences involved in nonhomologous recombination events in the beta-globin gene region.

Aged↗
PubMed1987

Sardinian delta beta zero-thalassemia: a further example of a C to T substitution at position -196 of the A gamma globin gene promoter.

Selective overexpression (50- to 100-fold) in adult erythroid cells of either G gamma or A gamma fetal globin gene is observed in hereditary conditions known as delta beta zero-thalassemia and hereditary persistence of fetal hemoglobin (HPFH). Recently, a C----T change at position -196 of an overexpressed A gamma globin gene from an Italian HPFH was hypothesized, on the basis of indirect evidence, to represent the cause of the functional defect. We now show that the same mutation is present in a different overexpressed A gamma-globin gene from a Sardinian patient with a different syndrome (delta beta zero-thalassemia). The Sardinian A gamma globin gene differs from both the HPFH and the normal A gamma globin gene at nucleotide 1,560 in the noncoding portion of the third exon, where an A is deleted. In addition, the mutant -196 A gamma-globin gene is linked to a normal beta globin gene in HPFH, and to a beta-thalassemic gene (beta 39CAG----TAG) in delta beta zero-thalassemia. These data strengthen the suggestion that -196 mutation is causally linked to the abnormal phenotype and raise the question of whether the same or multiple mutational events are responsible for the appearance of the -196 mutation in different syndromes.

Base Sequence↗
PubMed1985

Genetic defects in the thalassemias.

In summary, the beta-thalassemias are models for the study of human genetic disease. Defining the genetic defects in and surrounding the beta-globin gene in the beta(+)- and the beta(0)-thalassemias has resulted in new insights into the relationships between changes in gene structure and abnormalities in gene function. The region 5' to the beta-gene, the coding regions within the gene, and the IVS have all been found to contain single nucleotide defects which diminish or abolish beta-globin mRNA production and the production of beta-globin. The ability to isolate beta-globin genes by cloning, and to express these beta-globin genes in cells, has given remarkable insights into the relationship between globin gene structure and globin gene function. In addition, new technology is available for the antenatal diagnosis of the beta-thalassemias based on the knowledge of the specific defects in these genes, with the use of oligomers to detect single nucleotide changes. Finally, recent advances have suggested new approaches to gene therapy in these disorders using gene transfer.

Cloning, Molecular↗