Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Beta-thalassemia major is one of the commonest genetic disorders in South-East Asia. The spectrum of beta-thalassemia mutations in the various ethnic sub-populations on the island of Borneo is unknown. We studied 20 Dusun children from the East Malaysian state of Sabah (North Borneo) with a severe beta-thalassemia major phenotype, using a combination of Southern analysis, polymerase chain reaction analysis and direct sequencing. We found the children to be homozygous for a large deletion, which has a 5' breakpoint at position -4279 from the cap site of the beta-globin gene (HBB) with the 3' breakpoint located in a L1 family of repetitive sequences at an unknown distance from the beta-globin gene. This was similar to a recent finding of a large deletion causing beta-thalassemia first described in unrelated beta-thalassemia heterozygotes of Filipino descent. This report describes the first 20 families with homozygosity of the deletion causing a severe phenotype. It provides the first information on the molecular epidemiology of beta-thalassemia in Sabah. This finding has implications for the population genetics and preventative strategies for beta-thalassemia major for nearly 300 million individuals in South-East Asia.
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PMID:A single, large deletion accounts for all the beta-globin gene mutations in twenty families from Sabah (North Borneo), Malaysia. Mutation in brief no. 240. Online. 1033

In order to establish the molecular basis of beta-thalassaemia in Cubans, a total of 75 unrelated individuals, with beta-thalassaemia major (7), Hb S-beta-thalassaemia (28), Hb C-beta-thalassaemia (1), and beta-thalassaemia trait (39) yielding 82 beta-thalassaemia alleles, were analyzed. Seventeen different point mutations were identified accounting for 93% of the beta-thalassaemia alleles studied, revealing a high genetic heterogeneity at the HBB locus in this population. The more prevalent mutations, namely, CD 39 (C --> T) (30.5%), -29 (A --> G) (13.4%), IVS-I-110 (G --> A) (8.5%), and IVS-II-1 (G --> A) (8.5%), reflect the Mediterranean and African predominant ancestry of the extant Cuban population. We also report the identification of a novel allele, IVS-I-108 (T --> C), that possibly activates a cryptic branch site, in a beta-thalassaemia carrier with no other molecular defect within the beta-globin gene and its proximal promoter. This study shows that prenatal diagnosis of beta-thalassaemia should be feasible in about 60% of at-risk pregnancies by direct detection of selected point mutations. However, due to the wide spectrum of mutations, and in order to offer fully informative prenatal diagnosis to more than 87% of at-risk couples, the screening for beta-thalassaemia mutations in Cubans should be performed by using a general point mutation detection method, such as DGGE (denaturing gradient gel electrophoresis).
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PMID:Beta-thalassaemia in Cubans: novel allele increases the genetic diversity at the HBB locus in the Caribbean. 1081 81

The population of Quebec, Canada (7.3 million) contains approximately 6 million French Canadians; they are the descendants of approximately 8500 permanent French settlers who colonized Nouvelle France between 1608 and 1759. Their well-documented settlements, internal migrations, and natural increase over four centuries in relative isolation (geographic, linguistic, etc.) contain important evidence of social transmission of demographic behavior that contributed to effective family size and population structure. This history is reflected in at least 22 Mendelian diseases, occurring at unusually high prevalence in its subpopulations. Immigration of non-French persons during the past 250 years has given the Quebec population further inhomogeneity, which is apparent in allelic diversity at various loci. The histories of Quebec's subpopulations are, to a great extent, the histories of their alleles. Rare pathogenic alleles with high penetrance and associated haplotypes at 10 loci (CFTR, FAH, HBB, HEXA, LDLR, LPL, PAH, PABP2, PDDR, and SACS) are expressed in probands with cystic fibrosis, tyrosinemia, beta-thalassemia, Tay-Sachs, familial hypercholesterolemia, hyperchylomicronemia, PKU, oculopharyngeal muscular dystrophy, pseudo vitamin D deficiency rickets, and spastic ataxia of Charlevoix-Saguenay, respectively) reveal the interpopulation and intrapopulation genetic diversity of Quebec. Inbreeding does not explain the clustering and prevalence of these genetic diseases; genealogical reconstructions buttressed by molecular evidence point to founder effects and genetic drift in multiple instances. Genealogical estimates of historical meioses and analysis of linkage disequilibrium show that sectors of this young population are suitable for linkage disequilibrium mapping of rare alleles. How the population benefits from what is being learned about its structure and how its uniqueness could facilitate construction of a genomic map of linkage disequilibrium are discussed.
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PMID:Human genetics: lessons from Quebec populations. 1170 44

Beta-thalassemia is a common inherited disease, resulting from one or more of a total of more than 200 different mutations in the beta-globin gene (HBB). Efficient and reliable mutation-screening methods are essential in order to establish appropriate prevention programs for at-risk populations based upon a molecular diagnosis. We have developed a rapid and highly-specific mutation screening test for the diagnosis of beta-thalassemia by coupling heteroduplex and primer-extension analysis based on the denaturing high performance liquid chromatography (DHPLC) system. A total of 161 healthy heterozygous Taiwanese carriers featuring 10 different HBB mutations and 30 patients exhibiting 12 different compound heterozygous or homozygous HBB mutations were subjected to DHPLC. The elution profile for the heteroduplex analysis of DHPLC could be successfully used to identify the common disease-causing mutations of HBB. To further confirm the sequence variants, we developed a technique combining multiplex primer-extension analysis coupled with DHPLC for the genotyping of eight common disease-causing mutations in the HBB gene. Overall, by coupling heteroduplex and primer-extension analysis based upon DHPLC, we were able to unambiguously identify the most-common beta-thalassemia mutations corresponding to more than 99% of HBB alleles among the Taiwanese population. In conclusion, compared to classic approaches to mutation screening for this malady, we suggest that DHPLC is an excellent technique to be applied to the genetic screening of prenatal and postnatal individuals as a part of a diagnosis program for beta-thalassemia and provides a more-efficient, economic, and sensitive means to undertake such a screening program.
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PMID:Rapid detection of beta-globin gene (HBB) mutations coupling heteroduplex and primer-extension analysis by DHPLC. 1295 18

The analysis of circulating nucleic acids has revealed applications in the noninvasive diagnosis, monitoring, and prognostication of many clinical conditions. Circulating fetal-specific sequences have been detected and constitute a fraction of the total DNA in maternal plasma. The diagnostic reliability of circulating DNA analysis depends on the fractional concentration of the targeted sequence, the analytical sensitivity, and the specificity. The robust discrimination of single-nucleotide differences between circulating DNA species is technically challenging and demands the adoption of highly sensitive and specific analytical systems. We have developed a method based on single-allele base extension reaction and MS, which allows for the reliable detection of fetal-specific alleles, including point mutations and single-nucleotide polymorphisms, in maternal plasma. The approach was applied to exclude the fetal inheritance of the four most common Southeast Asian beta-thalassemia mutations in at-risk pregnancies between weeks 7 and 21 of gestation. Fetal genotypes were correctly predicted in all cases studied. Fetal haplotype analysis based on a single-nucleotide polymorphism linked to the beta-globin locus, HBB, in maternal plasma also was achieved. Consequently, noninvasive prenatal diagnosis in a mother and father carrying identical beta-thalassemia mutations was accomplished. These advances will help in catalyzing the clinical applications of fetal nucleic acids in maternal plasma. This analytical approach also will have implications for many other applications of circulating nucleic acids in areas such as oncology and transplantation.
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PMID:MS analysis of single-nucleotide differences in circulating nucleic acids: Application to noninvasive prenatal diagnosis. 1524 15

Hemoglobinopathies constitute a major health problem worldwide, with a high carrier frequency, particularly in certain regions where malaria has been endemic. These disorders are characterized by a vast clinical and hematological phenotypic heterogeneity. Over 1,200 different genetic alterations that affect the DNA sequence of the human alpha-like (HBZ, HBA2, HBA1, and HBQ1) and beta-like (HBE1, HBG2, HBG1, HBD, and HBB) globin genes are mainly responsible for the observed clinical heterogeneity. These mutations, together with detailed information about the resulting phenotype, are documented in the globin locus-specific HbVar database. Family studies and comprehensive hematological analyses provide useful insights for accurately diagnosing thalassemia at the DNA level. For this purpose, numerous techniques can provide accurate, rapid, and cost-effective identification of the underlying genetic defect in affected individuals. The aim of this article is to review the diverse methodological and technical platforms available for the molecular diagnosis of inherited disorders, using thalassemia and hemoglobinopathies as a model. This article also attempts to shed light on issues closely related to thalassemia diagnostics, such as prenatal and preimplantation genetic diagnoses and genetic counseling, for better-quality disease management.
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PMID:Molecular diagnosis of inherited disorders: lessons from hemoglobinopathies. 1613 10

Mutations in the delta-globin gene (HBD, MIM# 142000) are not pathologically relevant. However, since high HbA2 levels are diagnostic for beta-thalassemia trait and a lowered level for an alpha- or delta-mutation, co-inheritance of delta- and beta-gene defects may lead to misinterpretation of diagnostic results. We examined 29 cases with low HbA2 level diagnosed in our laboratory, in the presence or absence of a second HbA2 fraction. We found a delta globin gene mutation in 20 cases. In total four different known mutations were found, three structural and one expressional. Moreover, two new defects were observed, one causing a structural abnormality and one a beta-thalassemia. The structural abnormality HBD c.431A->G (p.His144Arg)(dcd 143 CAC->CGC) was homologous to the beta-globin gene variant called Hb-Abruzzo and we have named this mutation HbA2 -Abruzzo. The new delta-thalassemia defect HBD c.-118C->T (d -68 C->T) has no homology on the beta-globin gene (HBB, MIM# 141900). All mutations caused a low HbA2 level and through this could lead to misdiagnosis when inherited together with a beta-thalassemia.
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PMID:Known and new delta globin gene mutations and their diagnostic significance. 1643 82

A young woman originally from Cape Verde islands presented with mild sickle cell disease. Her blood counts and hemoglobin analysis results initially suggested that she might be either homozygous for the sickle cell hemoglobin (Hb S) with concomitant alpha-thalassemia, or compound heterozygous for Hb S and beta0-thalassemia, deletional deltabeta-thalassemia or hereditary persistence of fetal hemoglobin (HPFH). We utilized a novel polymerase chain reaction (PCR)-based screening technique and found a hitherto unrecognized 7.7-kb deletion, starting from the HBB IVSII to 3' downstream of the beta-globin gene. This diagnostic approach can be applied to decipher other similar deletional mutations. This is the second known deletion that removes the 3'-end but preserves the integrity of the 5'-end of the beta-globin gene. Furthermore, the identification of the deletion allows proper genetic counseling for affected families.
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PMID:Sickle cell disease due to compound heterozygosity for Hb S and a novel 7.7-kb beta-globin gene deletion. 1703 17

Codon 104(-G), a heterozygous frameshift mutation in exon 2 of HBB, resulted in a dominantly inherited beta0-phenotype with mild anemia in a German kindred, and thalassemia intermedia in the index patient. A co-inherited a gene triplication, long-term transfusion therapy, and ineffective erythropoiesis were confounding factors.
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PMID:Codon 104(-G), a dominant beta0-thalassemia-like phenotype in a German Caucasian family is associated with mild chronic hemolytic anemia but influenced in severity by co-inherited genetic factors. 1776 22

Free circulating DNA is present in the plasma of healthy subjects, and is elevated in conditions characterized by increased cell death, such as cancer and physical trauma. Analysis of circulating DNA in plasma could provide a useful biomarker in sickle cell disease (SCD) in view of the increased cell turnover through chronic ongoing haemolysis, recurrent vaso-occlusion and inflammation. Plasma DNA was determined by real-time quantitative polymerase chain reaction (PCR) amplification of the beta-globin gene (HBB) in 154 patients with SCD [105 haemoglobin (Hb)SS, 46 HbSC and three HbS/beta(0) thalassaemia] and 53 ethnically matched controls. Blood samples were obtained from all patients in steady state; 21 of the 154 patients were also sampled during admission to hospital for acute pain. Median concentration of circulating plasma DNA in acute pain was more than 10-fold that in steady state and in controls - 10070 vs. 841 and 10070 vs. 933 genome equivalents/ml respectively (P < 0.0001, in both cases). During steady state, patients had plasma DNA levels similar to controls. Plasma DNA levels in SCD correlated with C-reactive protein levels (P < 0.005) and total white cell counts (P < 0.05) in steady state. The study shows that plasma DNA concentration may have potential as a biomarker in sickle cell patients.
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PMID:Circulating DNA: a potential marker of sickle cell crisis. 1789 11


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