Hemoglobin Profiles and Hematologic Features of Thalassemic Newborns: Application to Screening of α-Thalassemia 1 and Hemoglobin E
01 Nov 2008-Archives of Pathology & Laboratory Medicine (Arch Pathol Lab Med)-Vol. 132, Iss: 11, pp 1739-1745
TL;DR: Effective primary screening with 100% accuracy for alpha-thalassemia 1 and hemoglobin E in newborns in the region could be carried out using means corpuscular volume less than 95 fL, mean corpuscular hemoglobin less than 30 pg, or hemoglobin Bart greater than 8.0% and Hemoglobin E greater than 0.5%, respectively.
Abstract: Context.—Thalassemia and hemoglobinopathies are major public health problems worldwide. To establish a cost-effective screening tool for newborns in regions where the incidence of these disorders is significant, study of the hemoglobin and hematologic features of normal and thalassemic newborns is necessary. Objective.—To study hemoglobin and hematologic characteristics of normal and various thalassemic newborns and to assess the effectiveness of simple screening methods for α-thalassemia 1 and hemoglobin E. Design.—Study was made of 402 cord blood specimens collected from unrelated Thai individuals. Hematologic parameters and hemoglobin profiles were determined. Thalassemia mutations were identified using polymerase chain reaction–related techniques. Results.—As many as 178 subjects (44.3%) were found to carry thalassemia genes with 18 different genotypes. All forms of α-thalassemia including double heterozygote for hemoglobin E and α-thalassemia showed significant reduction in hemoglobin, mean ...
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TL;DR: Prenatal diagnosis of severe α‐ and β‐thalasssemia diseases is usually performed by DNA analysis, and the results can vary greatly depending on the mother's sex and the underlying disease.
Abstract: Introduction: Prenatal diagnosis of severe α- and β-thalasssemia diseases is usually performed by DNA analysis.
Objective: To establish a simple method, we have evaluated the reliability of prenatal diagnosis by fetal blood analysis using automated capillary electrophoresis system.
Methods: Forty-seven fetal blood specimens collected by cordocentesis at 18–28 wk of gestation were analyzed by the capillary electrophoresis system (Sebia). Fetal DNA was analyzed for respective thalassemia alleles by PCR.
Results: Among 47 fetuses, 20 were at risk for the Hb Bart’s hydrops fetalis. DNA analysis identified four cases of homozygous α°-thalassemia (SEA type). Hb analysis by the capillary electrophoresis demonstrated a major peak of Hb Bart’s (78.4–81.3%), Hb H (0.8–1.4%) and minor peaks of presumably embryonic Hbs. No Hb F and Hb A was observed. The level of Hb Bart’s was found to be 3.4–5.8% in unaffected heterozygote whereas normal fetus had no Hb Bart’s. Among the remaining 27 fetuses at risk for Hb E-β-thalassemia, DNA analysis identified 12 affected fetuses. Hb analysis showed Hb F (94.9–98.9%) and Hb E (1.1–1.8%) without Hb A in all cases. The levels of Hb A were found to be (4.3–7.2%), (1.0–5.5%) and (2.1–3.9%) in normal, heterozygous Hb E and heterozygous β-thalassemia fetuses, respectively. Affected and unaffected fetuses could be easily distinguished.
Conclusion: Capillary electrophoresis system is a simple and automated procedure for accurate prenatal diagnosis of severe thalassemia diseases which could readily be performed in routine setting.
48 citations
Cites background from "Hemoglobin Profiles and Hematologic..."
...Hb Bart’s is a homotetramer of excess c-globin chain (c4) which has been shown to be useful for diagnosis of a-thalassemia in newborns (33)....
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TL;DR: The capillary electrophoresis system is applicable to newborn screening for common forms of thalassemia in Southeast Asia and could provide useful data for presumptive diagnoses of cases, especially those with Hb E and α-thalassemia.
30 citations
Cites background or methods from "Hemoglobin Profiles and Hematologic..."
...The same findings have beennoted on theHPLC and IEF formats [16,17]....
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...As for our previous study usingHPLC analysis [16], Hb Bart's could be observed in all of them....
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TL;DR: IEF was a reliable method for neonatal cord blood screening for alpha-thalassemia and Hb variants and could clearly distinguish Hb H diseases and carriers of two alpha-globin gene defects from normal individuals according to the presence of Hb Bart's and its percentage.
Abstract: We describe the screening of newborns for thalassemia and Hb variants by using isoelectric focusing (IEF) in a population from northern Thailand where hemoglobinopathies are highly prevalent. The report focuses on findings of alpha-thalassemia, Hb E, and other hemoglobin variants, and their correlation with genotypes and hematologic parameters. Two-hundred and seven out of 566 newborns (36.6%) had thalassemia genes or Hb variants. Seventeen different genotypes were found. Nine cases (1.6%) of Hb H disease (five deletional Hb H diseases, two Hb H/Constant Spring diseases, one deletional Hb H disease/Hb E, carrier and one Hb H/Constant Spring disease/Hb E carrier) and one Hb E-beta-thalassemia were identified. IEF could clearly distinguish Hb H diseases and carriers of two alpha-globin gene defects from normal individuals according to the presence of Hb Bart's and its percentage. For carriers of a single alpha-globin gene defect, Hb Bart's was either absent or present in a small amount and was therefore not reliable for screening. The presence of an additional band at the Hb A(2) position in the newborns signified an Hb E carrier. One case of an absent Hb A and a presence of Hb E was identified as Hb E-beta-thalassemia. Two Hb Q-Thailand carriers were seen with two additional Hb fractions, presumably combinations of gamma-globin and beta-globin with the alpha-globin variant. Newborns with Hb H disease had lower Hb, MCV, and MCH levels than normal. MCV and MCH were also useful for differentiation of carriers of two alpha-globin gene defects, but not for carriers of Hb E or single alpha-globin gene defect. IEF was a reliable method for neonatal cord blood screening for alpha-thalassemia and Hb variants.
26 citations
TL;DR: Thalassemia screening in newborns in northeast Thailand indicates a need for continuing a prevention and control program in the region and reveals that α-thalassemia, β-thalassesmia, and Hb E carriers as well as complex thalassemi syndromes are still prevalence.
Abstract: Background: To provide accurate prevalence information of thalassemia in northeast Thailand after 20 years implementation of a prevention and control program, thalassemia screening was carried out in newborns Methods: Study was done on 350 cord blood specimens collected consecutively at Maternal and Child Hospital, Regional Health Promotion Center 7, Khon Kaen, Thailand All kinds of a- and β-thalassemias were identified using combined hemoglobin (Hb) and DNA analyses Results: Among 350 newborns examined, subjects with thalassemia genes were identified in 184 (526%) cases with as many as 22 different genotypes The most prevalent one was Hb E (391%) The incidence of 31% a 0 -thalassemia, 259% a + -thalassemia, 54% Hb Constant Spring and 14% of Hb Pakse were encountered Heterozygous β-thalassemia was found in 2 cases (06%) Hb capillary electrophoresis could demonstrate Hb E in all cases with Hb E and detected different levels of Hb Bart’s for different a-thalassemia genotypes but not in all cases with a-thalassemia No newborn with severe thalassemia diseases was encountered Conclusion: This study reveals that a-thalassemia, β-thalassemia and Hb E carriers as well as complex thalassemia syndromes are still prevalence and indicates a need for continuing a prevention and control program in the region
17 citations
Journal Article•
TL;DR: MCV and MCH values can be helpful for the selection of the appropriate molecular tests to determine the genotype of alphathalassemia carriers.
Abstract: Alpha thalassemia (α-thal) is relatively common worldwide. Most carriers are defective in either one or two alpha globin genes out of four functional ones, with deletions being more common than point mutations. The hematologic features are very important for the selection of the appropriate molecular tests while determining the genotype. The aim of this study was to compare hematologic features of patients with various types of α globin mutations. Hematological indices including red blood cells (RBC), hemoglobin concentration (Hb), mean cell volume (MCV), mean cell hemoglobin (MCH), Mean corpuscular hemoglobin concentration (MCHC) and percentage of Hemoglobin (HBA1, HBA2 and HBF) of seven-hundred and twenty two patients presenting ten different α-thal genotypes were considered. All patients showed reduced MCV and/or MCH values.Moreover, MCV and MCH were lower in patients with two functional alpha globin genes in comparison to patients with one mutated alpha globin gene (P value<0.001). In conclusion, MCV and MCH valuescan be helpful for the selection of the appropriate molecular tests to determine the genotype of alphathalassemia carriers.
16 citations
References
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TL;DR: It takes considerable time to establish expertise in developing programmes for the control and management of these conditions, and the lessons learned in developed countries will need to be transmitted to those countries in which they occur at a high frequency.
Abstract: Despite major advances in our understanding of the molecular pathology, pathophysiology, and control and management of the inherited disorders of haemoglobin, thousands of infants and children with these diseases are dying through lack of appropriate medical care. This problem will undoubtedly increase over the next 20 years because, as the result of a reduction in childhood mortality due to infection and malnutrition, more babies with haemoglobin disorders will survive to present for treatment. Although WHO and various voluntary agencies have tried to disseminate information about these diseases, they are rarely mentioned as being sufficiently important to be included in setting health care priorities for the future. It takes considerable time to establish expertise in developing programmes for the control and management of these conditions, and the lessons learned in developed countries will need to be transmitted to those countries in which they occur at a high frequency.
1,121 citations
TL;DR: Cet article etudie successivement la frequence de la thalassemie β, des variants genetiques de la chaine α et de the chaine β, de l'hemoglobine constant spring et oficiairement l'HbE.
Abstract: Cet article etudie successivement la frequence de la thalassemie α, de la thalassemie β, des variants genetiques de la chaine α et de la chaine β, de l'hemoglobine constant spring et de l'HbE
298 citations
TL;DR: A combined test using OF and DCIP could be used as an effective preliminary screening alternative to an electronic blood cell count for identifying carriers with alpha(o)-thalassaemia, beta-thalASSaemia and Hb E.
Abstract: Objective To evaluate a simple screening strategy for thalassaemia and haemoglobin (Hb) E in a prevention and control programme for thalassaemia in rural communities with limited resources. Methods Blood samples from 301 Thai–Khmer participants were screened for thalassaemia and Hb E using a combined modified one-tube osmotic fragility (OF) test and a modified dichlorophenolindophenol (DCIP) precipitation test. Results were evaluated with standard haematological analyses including erythrocyte indices, Hb typing and quantification and polymerase chain reaction (PCR) analysis of α-globin and β-globin genes. Findings Participants were divided into four groups according to the results of the combined tests. Altogether, 104 of 301 participants (34.6%) had negative results on both tests; 48 (15.9%) were positive on the OF test but not the DCIP test; 40 (13.3%) were negative on the OF test but positive on DCIP test; and 109 (36.2%) were positive on both tests. No carrier of clinically significant forms of thalassaemia (αo-thalassaemia, β-thalassaemia) or Hb E was found among the group that had negative results for both tests. All participants with Hb E had positive DCIP tests. Carriers of α + -thalassaemia or Hb Constant Spring could generate either positive or negative OF test results but they all had negative DCIP tests. Using both tests as a preliminary screening for the three important groups of carriers gave a sensitivity of 100% and a specificity of 69.8%. The positive predictive value of the combined test was 77.2%. The negative predictive value was 100%. Further evaluation of the screening system by local staff at three community hospitals found a sensitivity of 98.1–100% and a specificity of 65.4–88.4% with positive predictive values of 75.0–86.9% and negative predictive values of 98.1–100%. Conclusion A combined test using OF and DCIP could be used as an effective preliminary screening alternative to an electronic blood cell count for identifying carriers with αo-thalassaemia, β-thalassaemia and Hb E. The strategy should prove useful for population screening in prevention and control programmes in rural communities in south-east Asia where laboratory facilities and economic resources are limited.
186 citations
TL;DR: The interaction of several globin gene abnormalities in Cambodian families emphasizes the high frequencies of thalassemia and hemoglobinopathies and a simplified PCR assay for simultaneous detection of HbCS and HbPS would facilitate characterization of these genotypes in both the clinical setting and population screening programs in the region.
Abstract: BACKGROUND AND OBJECTIVES: This study aimed to describe hematologic and molecular characterization of the interaction of hemoglobin (Hb) E and several forms of alpha-thalassemia causing complex thalassemia syndromes in two Cambodian families as well as to establish a rapid polymerase chain reaction (PCR) assay for simultaneous detection of Hb Constant Spring (CS) and Hb Pakse' (PS). DESIGN AND METHODS: Using PCR and DNA sequencing, the alpha- and beta-globin genotypes were examined. Clinical and hematologic data were assessed. A multiplex asymmetric allele-specific PCR for differential diagnosis of HbCS and HbPS was developed and validated. RESULTS: Eight genotypes including heterozygous HbCS, heterozygous HbPS, double heterozygous HbE/HbPS, double heterozygous HbE/alpha-thalassemia 2, triple heterozygous HbE/alpha-thalassemia /HbPS, homozygous HbE/alpha-thalassemia 2, compound alpha-thalassemia 2/HbCS and a hitherto undescribed compound HbCS/HbPS were found in these two families. Genotype-phenotype relationships are discussed and successful application of a multiplex PCR system for differential diagnosis of HbCS and HbPS is described. INTERPRETATION AND CONCLUSIONS: The interaction of several globin gene abnormalities in Cambodian families emphasizes the high frequencies of thalassemia and hemoglobinopathies. Identification of HbPS suggests that this mutation might be common and underestimated among South-east Asian populations. A simplified PCR assay for simultaneous detection of HbCS and HbPS would facilitate characterization of these genotypes in both the clinical setting and population screening programs in the region.
121 citations
TL;DR: A combination of modified osmotic fragility (OF) and DCIP tests should prove useful and applicable to prenatal screening programs for thalassemia and hemoglobinopathies in communities with limited facilities and economic resources.
Abstract: Primary screening for thalassemia and hemoglobinopathies usually involves an accurate blood count using an expensive electronic blood cell counter A cheaper alternative method was tested by using a modified osmotic fragility (OF) test and a modified dichlorophenolindophenol (DCIP) test Altogether 423 pregnant Thai women participated in this project Hemoglobin patterns and globin genotypes were determined using an automated high-performance liquid chromatography analyzer and polymerase chain reaction analysis of alpha- and beta-globin genes Among the 423 subjects, 264 (624%) carried thalassemia genes The combined OF and DCIP tests detected all pregnant carriers of the 3 clinically important thalassemias, ie, alpha0-thalassemia, beta-thalassemia, and hemoglobin E with a sensitivity of 1000%, specificity of 871%, positive predictive value of 845%, and negative predictive value of 1000%, which show more effectiveness than these values for the standard method based on RBC counts A combination of modified OF and DCIP tests should prove useful and applicable to prenatal screening programs for thalassemia and hemoglobinopathies in communities with limited facilities and economic resources
107 citations