Antenatal testing for haemoglobinopathies.
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Female↗
Biomedical subjects
B J Wild
Publications and source records attributed to B J Wild.
Hyperhemolytic transfusion reaction in sickle cell disease.
BACKGROUND: An atypical form of life-threatening hemolytic transfusion reaction (HTR) in patients with sickle cell disease (SCD) has been well described in the literature. Continuation of blood transfusion may be lethal, as it can further exacerbate hemolysis. The pathophysiologic mechanism of HTR is not well understood. CASE REPORTS: Two cases of severe HTR in SCD after the transfusion of compatible RBC units are reported. Hemolysis of both autologous and transfused cells was documented in Case 1 by urine Hb high-performance liquid chromotography. Multispecific HLA antibodies were identified in Case 1. Reticulocytopenia was noted in both cases during the acute hemolytic process. This was followed by a rise in reticulocyte count during receipt of IVIG and steroid therapy. Bone marrow examination during reticulocytopenia in Case 2 showed erythroid hyperplasia. CONCLUSION: In SCD, both mature sickle cells and sickle reticulocytes adhere more readily to macrophages. In view of the bone marrow aspiration results, it appears that the recipients' HbS cells are destroyed by hyperactive macrophages and that the reticulocytopenia observed during HTR is likely to be due to peripheral consumption (i.e., destruction by macrophages), rather than suppression of erythropoiesis. Cessation of hemolysis during IVIG and steroid treatment may be due to IVIG's blocking of the adhesion of sickle cells and reticulocytes to macrophages, together with steroid suppression of macrophage activity.
Adult↗
Quantification of Ggamma- and Agamma-globins by electrospray ionisation mass spectrometry.
Elucidation of the molecular basis for persistent fetal haemoglobin (Hb F) production in adult life has important implications for the pathophysiology and treatment of human beta haemoglobinopathies. Electrospray ionisation mass spectrometry (ESMS) was applied to analyse the pattern of gamma-globin expression in patients with hereditary persistence of fetal haemoglobin (HPFH) and sickle cell anaemia (SCA). Ggamma and Agamma-globin chains were identified by their measured molecular masses and distinguished by mass difference (14 Da) following deconvolution of ESMS spectra using maximum entropy based software. Prediction of HPFH type by ESMS was confirmed by molecular analysis. Direct determination of Ggamma:Agamma globin chain ratio from whole blood by the novel application of ESMS provides a rapid and sensitive approach to characterisation of gamma-globins and facilitates correlation of gamma-globin level and polymorphism of cis-active elements at the beta-globin locus.
Adult↗
The use of automated HPLC to detect and quantitate haemoglobins.
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.
Adult↗
Rapid identification of hemoglobin variants by electrospray ionization mass spectrometry.
The precise identification of human hemoglobin variants, over 700 human hemoglobin variants are known, is essential for prediction of their clinical and genetic significance. A systematic approach to their rapid identification is described. Traditionally this requires protein or DNA characterization which entails lengthy analytical procedures. To overcome these obstacles a rapid approach to variant hemoglobin identification has been developed using conventional phenotypic methods combined with electrospray ionization-mass spectrometry (ESI-MS). The latter requires only a small amount of whole blood (10 microl) but in most cases 2 microl would have been sufficient and no preanalytical steps, such as separation of red cells or globin chains, are necessary. Aged, hemolyzed blood samples can also be analyzed. This approach has been used to positively identify 95% of the variants in over 250 samples. The remaining 5% in which a variant was detected by phenotypic techniques were not resolved by mass spectrometry. Ninety-nine different abnormalities comprising 36 alpha-chain variants, 59 beta-chain variants (including 2 extensions), and 4 hybrid hemoglobins were identified. These include 15 novel variants. The application of ESI-MS described requires approximately 1 h to prepare and analyze each sample and has minimal reagent costs. The turnaround time on a single sample can be as little as 2 h. This technique can now be considered a useful additional tool for reference laboratories.
Amino Acid Substitution↗
The potential of electrospray ionization mass spectrometry for the diagnosis of hemoglobin variants found in newborn screening.
Analytical procedures have been developed for the detection and diagnosis of sickle cell disease in newborn babies by analyzing the hemoglobin extracted from dried blood spots on Guthrie cards using electrospray ionization mass spectrometry (ESI-MS). An essential requirement is the ability to reliably differentiate two globin chains whose molecular weights differ by only 1 Da such as adult hemoglobin (Hb A) and Hb C. This has been achieved by improving the accuracy and precision of the molecular weight determination to a fraction of a dalton. We report the potential of mass spectrometry for screening neonates for these debilitating diseases by presenting results from 147 blood spots that had been characterized by phenotypic methods and which include samples from 20 sickle cell disease, 1 beta-thalassemia major, 57 sickle cell trait, and 39 normal babies. In all cases, the mass spectrometric results agreed with the results obtained using conventional analytical practice with high-performance liquid chromatography (HPLC) and isoelectric focusing (IEF). We show that mass spectrometry is a viable technique for the diagnosis of newborns with sickle cell disease or homozygous beta0-thalassemia.
Anemia, Sickle Cell↗