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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The usual methods for prenatal diagnosis of beta-thalassemia and other hemoglobinopathies by assay of fetal blood erythrocytes are either complex (analysis of globin chains synthesis by carboxymethylcellulose chromatography) or only semiquantitative [isoelectric focusing of hemoglobin (Hb)]. To further simplify the diagnostic procedure and to obtain quantitative data, we measured the small concentrations of Hb A in fetal erythrocytes by using a high-pressure liquid chromatography (HPLC) instrument (DIAMAT-TM; Bio-Rad) equipped with the new column proposed for measuring Hb A2. We analyzed 212 uncontaminated fetal blood samples obtained by cordocentesis between the 18th and 22nd weeks of pregnancy, using the HPLC procedure, and compared the results with those obtained by the above-named methods. The Hb A values obtained ranged between 0% and 8.5%; they were less than or equal to 1.8% in 44 fetuses affected by homozygous beta-thalassemia and greater than 2.5% in 168 unaffected fetuses. The method was simple, rapid, and reproducible (CV 3.2%) and there was good correlation between Hb A concentrations determined by HPLC and the beta/gamma ratio determined by carboxymethylcellulose chromatography (r = 0.7687; P less than 0.0001). No false-negative or false-positive results were observed, and there was no overlap of values between affected and unaffected fetuses.
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PMID:Nonradioactive quantification of low concentrations of hemoglobin A by HPLC for midtrimester prenatal diagnosis of beta-thalassemia. 152 32

Total glycosylated haemoglobin was determined by a minicolumn ion-exchange chromatography technique (Bio-Rad) and correlated with the mean of fasting and post-prandial blood glucose values for the preceding 6 weeks. In 360 diabetic subjects, free of congenital haemoglobinopathies and other detected causes of haemoglobin A1 misinterpretation (reference diabetic group), a highly significant correlation was established between haemoglobin A1 and glucose (y = 0.54 X +4.91; r = 0.791; p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (HbS, C, D, E), the apparent haemoglobin A1 values were lower than expected according to the 95% confidence limits of the diabetic reference group. The apparent haemoglobin A1 value was above these limits in patient 29, with beta thalassaemia. Patients with inappropriate glycosylated haemoglobin values should be investigated for causes of haemoglobin A1 misinterpretation, in particular, haemoglobinopathies.
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PMID:Haemoglobinopathies: a pitfall in the assessment of glycosylated haemoglobin by ion-exchange chromatography. 653 54

A battery of relatively simple tests allows the presumptive identification of hemoglobin (Hb) variants, making unnecessary structural analysis by protein chemistry methods or DNA sequencing. The primary step in this strategy involves the use of a matrix of electrophoretic mobilities obtained under various experimental conditions. This leads to an unambiguous result in approximately 90% of the cases. Additional tests are required to characterize with more confidence the remaining 10%. We describe here the use of cation-exchange HPLC on the Bio-Rad Variant automated analyzer with the "beta Thalassemia Short" program. By comparing the elution time of 125 human Hb mutants, we found that some variants with almost identical pI values or produced by the same type of amino acid substitution displayed different elution times. We present several examples in which use of the HPLC profile helped establish the diagnosis.
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PMID:Cation-exchange HPLC evaluated for presumptive identification of hemoglobin variants. 899 Feb 19

The introduction of automation for haemoglobinopathy screening is an important advance in technology for haematology laboratories. This paper evaluates the utility of an automated HPLC instrument, the Bio-Rad 'Variant' for the detection and quantitation of the normal haemoglobins (Hb A, A2 and F) and the common abnormal haemoglobins (Hb S, C, DPunjab, E, OArab and Lepore) which need to be evaluated in laboratories undertaking carrier and/or neonatal screening for sickle cell and thalassaemia. The instrument only uses a small amount of whole blood (5 microliters), a 3 mm disc from a Guthrie spot may also be used for analysis of samples from neonates. It uses a 100 place automatic sampler with a cycle time of 6.5 min for adult samples (using the 'Beta Thalassaemia Short' reagent pack) and 3 min for neonatal samples. The automatic sampler also allows samples to be analysed 'out of hours'. A 'STAT'; position allows urgent samples to be analysed before, or during, a routine analytical run. All reagents, other consumables and application notes are provided by the suppliers. Other types of reagent packs, such as the 'Sickle Cell Short' for neonatal screening were not assessed during this study.
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PMID:The use of automated HPLC to detect and quantitate haemoglobins. 935 40

Fetuses with homozygous alpha-thalassemia 1, in which the deletion of all four alpha-globin genes results in the absence of any alpha-globin chains, are severely anemic with clinical features of hydrops fetalis. Definitive diagnosis of alpha-thalassemia 1 carriers is difficult since there are few red cell abnormalities. Recently Chui et al. found that minute amounts of embryonic zeta-globin chains are present in adult hemoglobin of the Southeast Asian type of alpha-thalassemia 1 carriers. In this study, we screened 521 cord bloods for alpha-thalassemia 1. Hemoglobin analysis, including quantitation of Hb Bart's, was performed using the automated HPLC, alpha-thalassemia short program (VARIANT, Bio-Rad, Hercules, CA). Of these, 200 cord blood samples in which Hb Bart's was demonstrated were tested for the presence of zeta-globin chains by ELISA using labeled anti-zeta monoclonal antibody. Zeta-globin ranged between 0.21 and 0.83% in 19 specimens carrying alpha-thalassemia 1 gene. In the remaining 90 out of 109 specimens in which Hb Bart's was greater than 1.2%, zeta-globin was less than 0.17%. DNA analysis revealed the presence of normal alpha-genotype and other types of alpha-thalassemia including alpha-thalassemia 2 and Hb Constant Spring. One false positive was found in which the zeta-globin was 0.25% by ELISA but in which PCR indicated an alpha-thalassemia 2 heterozygote. Ninety-one samples with Hb Bart's of less than 1.2% by HPLC are most likely normal with a zeta-globin range between 0 and 0.14%. This study also showed that the frequency of alpha-thalassemia 1 in Bangkok is 3.65%.
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PMID:Detection of zeta-globin chains in the cord blood by ELISA (enzyme-linked immunosorbent assay): rapid screening for alpha-thalassemia 1 (Southeast Asian type). 954 71

We describe the evaluation of the Bio-Rad BeTha Gene 1 kit (Bio-Rad Laboratories, Hercules, CA), a DNA-probe assay designed for the qualitative determination of the eight most common Mediterranean beta-thalassemia mutations. The kit utilizes the principle of allele-specific oligonucleotide (ASO) hybridization. Following sample preparation and in vitro DNA amplification by the polymerase chain reaction (PCR), an allele-specific detection of the amplified products by a nonradioactive enzymatic assay is performed. Genomic DNA is prepared from an individual's whole blood with a DNA purification matrix. In a second step, the beta-globin gene is amplified in a multiplex PCR reaction containing four 5' biotinylated oligonucleotide primers. In a final step, an aliquot of the PCR reaction is first chemically denatured and then captured in two eight-well strips of a 96-well enzyme-linked immunosorbent assay (ELISA) plate by hybridization to an immobilized ASO probe. Each DNA sequence at each of the eight mutation sites is represented by one normal and one mutant ASO. During this capture/hybridization step, which is performed at 37 degrees C, only perfectly matched PCR products will be captured by an ASO. Subsequently, the allele-specific captured biotin-labeled PCR products are detected by a colorimetric enzymatic reaction. The system permits the detection of 16 beta-thalassemia alleles using a high-throughput format that can be automated easily. A clinical feasibility study was performed to evaluate the functionality (method comparison study, assay validity using samples previously collected and stored at various temperatures for different periods of time, interference on kit performance, and assay validity for prenatal diagnosis) and the usability (ease of use, sample throughput) of the kit. The analysis of 110 samples previously studied with reference methods showed 100% clinical sensitivity and specificity. We demonstrate here that the procedure not only increases the throughput of beta-thalassemia allele genotyping but also provides an accurate, rapid, reliable, and nonisotopic diagnostic tool.
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PMID:Evaluation of the BeTha gene 1 kit for the qualitative detection of the eight most common Mediterranean beta-thalassemia mutations. 979 59

The Bio-Rad Variant Hemoglobin testing system is an automated high performance liquid chromatography analyzer marketed with a beta-thalassemia short program to quantify Hbs F and A2, and assist in detecting Hbs A, S, D, C, and E. Although the two hemoglobins present in Hb H disease, Hb Bart's and Hb H, are separated by the system, they are not quantitated. In this study we modified the beta-thalassemia short program in order to facilitate quantitation of Hb Bart's and Hb H. Blood samples from 60 patients with Hb H disease, with various underlying genotypes, were studied. Analyses were performed on the day of blood collection or on hemolysates stored at -80 degrees C in cyanide or carbomonoxy forms. The mean sum of Hb Bart's and Hb H levels in all patients was found to be 12% (range 1.8-35%). Patients with nondeletional mutations (or association of alpha(0) deletion and nondeletional mutations) had notably higher Hb Bart's and Hb H levels when compared to patients with deletional genotypes.
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PMID:Rapid and accurate quantitation of Hb Bart's and Hb H using weak cation exchange high performance liquid chromatography: correlation with the alpha-thalassemia genotype. 1049 Jan 32

The aim of the present study was to evaluate the point mutations of beta-thalassemia patients from the Aegean region of Turkey by using an allele-specific oligonucleotide hybridization technique. DNA isolated from peripheral blood samples of 75 children with beta-thalassemia major or intermedia was analyzed using a Bio-Rad mD(x)(TM)-Be Tha Gene 1 kit. We determined mutations in 56 (74.6%) patients. The allelic frequency of mutations in 150 chromosomes was as follows: IVS-I-110 (G-A) 44.1%, IVS-I-1 (G-A) 28.2%, IVS-I-6 (T-C) 13.3%, IVS-II-745 (C-G) 9.3%, IVS-II-1 (G-A) 2.7%, Cd 39 (C-T) 2.4%, -87 (C-G) 0% and Cd 6 (-A) 0%. The distribution of the mutation types was consistent with the findings of other research groups.
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PMID:Mutational analysis of beta-thalassemia cases from the Aegean region of Turkey using an allele-specific oligonucleotide hybridization technique. 1127 8

Among the few studies, producing contradictory results, done on the interaction of erythroid membrane skeletal spectrin with hemoglobin (Hb), none has been able to provide a quantitative estimate of the association of spectrin with Hb. In this work, studies on the interactions of erythroid spectrin with Hb have been elaborated upon using a novel fluorescence technique. The concentration-dependent change in the fluorescence intensity of fluorescein-conjugated spectrin (F-spectrin) in presence of oxy-Hb indicated binding with a dissociation constant of approximately 20 microM that has been directly evaluated from the increase in the extent of quenching of the fluorescein fluorescence of F-spectrin by reverse titration with the increasing concentrations of different Hb samples isolated from both normal and beta-thalassemic patients. The Hb compositions, with major components of the normal HbA, the fetal HbF, and the variant HbA2, of each individual were estimated using the Variant HPLC device of Bio-Rad. Results of the present study indicated that the dissociation constant, K(d), of spectrin binding to Hb decreased from 19.5 +/- 2 microM in normal individuals to of 6.5 +/- 0.5 microM in the presence of 73% HbA2 along with coeluted variants in the blood samples of patients suffering from beta-thalassemia, indicating differential interactions of the Hb variants with spectrin.
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PMID:Interaction of erythroid spectrin with hemoglobin variants: implications in beta-thalassemia. 1273 41

Accurate and precise hemoglobin separation and the quantitation of Hb A2 and Hb F are essential for the diagnosis of the thalassemias and hemoglobinopathies. Presented in this study is the validation of the the Hb A2 assay of the HbGold analyzer, a fully automated liquid chromatography system for hemoglobin separation and quantitation. Variability of Hb A2 quantitation was quite low; the CV's of within-run, between-run and interlaboratory studies were 1.8-3.1%, 3.4-6.0% and 6.8-8.8% respectively. The results of the %Hb A2 quantitated by HbGold analyzer correlated well with those given by the Bio-Rad Variant Hb testing system (r=0.98). The application of the HbGold analyzer for the diagnosis of the thalassemia phenotypes frequently observed in Thailand is considered. In conclusion, the Hb A2 assay of the HbGold analyzer could be used for the quantitation of Hb A2 and Hb F and the presumptive identification of abnormal hemoglobins.
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PMID:The validation of an automated liquid chromatography system for the diagnosis of thalassemias and hemoglobinopathies. 1275 40


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