Thalassemia and hemoglobinopathies in Southeast Asian newborns: diagnostic assessment using capillary electrophoresis system

Direct cord blood LAMP colorimetric phenol red assay for detecting α0-thalassemia (SEA deletion); the validation and post-natal screening in Thailand

Post-natal or newborn screening for thalassemia and hemoglobinopathies is useful for genetic counseling and managing thalassemia in children. We characterized thalassemia genotypes in newborns from the eastern part of Thailand. The results demonstrated a high heterogeneity of thalassemia and hemoglobinopathies with seventeen genotypes. We focused on α0- thalassemia (Southeast Asian [SEA] deletion) in this study. We developed and validated the loop-mediated isothermal amplification (LAMP) colorimetric assay for detecting α0- thalassemia (SEA deletion) using simple direct cord blood sampling compared to genomic DNA. A total of 160 cord blood samples were evaluated with the LAMP assay. The sensitivity and specificity of the LAMP colorimetric assay for α0-thalassemia (SEA deletion) using direct cord blood showed 100% (6/6 x 100) and 98.05% (151/154 x 100) whereas, genomic DNA showed 100% (6/6 x 100) and 100% (154/154 x 100), respectively. Moreover, we demonstrated other simple screening tools for α0-thalassemia with %Hb Bart's, MCV, and MCH values and found that these parameters were not diagnostic in our samples. The direct cord blood with colorimetric LAMP assay is simple, rapid, and does not require a post-LAMP step compared to conventional PCR. These techniques could be applied in post-natal or large population screening for α0-thalassemia (SEA deletion). Finally, this could support early prevention of complications, early management, genetic counseling for α-thalassemia disease in children, or a long-term prevention and control program of severe thalassemia in Thailand.

Wooden-Tip Electrospray Mass Spectrometry Characterization of Human Hemoglobin in Whole Blood Sample for Thalassemia Screening: A Pilot Study

Traditional analytical methods for thalassemia screening are needed to process complicated and time-consuming sample pretreatment. In recent decades, ambient mass spectrometry (MS) approaches have been proven to be an effective analytical strategy for direct sample analysis. In this work, we applied ambient MS with wooden-tip electrospray ionization (WT-ESI) for the direct analysis of raw human blood samples that were pre-identified by gene detection. A total of 319 whole blood samples were investigated in this work, including 100 α-thalassemia carriers, 67 β-thalassemia carriers, and 152 control healthy samples. Only one microliter of raw blood sample was directly loaded onto the surface of the wooden tip, and then five microliters of organic solvent and a high voltage of +3.0 kV were applied onto the wooden tip to generate spray ionization. Multiply charged ions of human hemoglobin (Hb) were directly observed by WT-ESI-MS from raw blood samples. The signal ratios of Hb chains were used to characterize two main types of thalassemia (α and β types) and healthy control blood samples. Our results suggested that the ratios of charged ions to Hb chains being at +13 would be an indicator for β-thalassemia screening.

Application of an optimized interpretation model in capillary hemoglobin electrophoresis for newborn thalassemia screening

INTRODUCTION

Newborn screening is an important supplement to thalassemia control and prevention. Capillary electrophoresis (CE) technology has several advantages for thalassemia screening but with low sensitivity, especially for thalassemia carriers. This study aims to illustrate the application of an optimized interpretation model in newborn thalassemia screening by capillary hemoglobin electrophoresis.

METHODS

Two thousand, two hundred fifty-eight neonates selected from four regions in China were enrolled and were screened for α-thalassemia and β-thalassemia by capillary electrophoresis. Results were interpreted based on an optimized model integrated with multiple parameters. Molecular analysis was carried out in synchrony and used as the gold standard for the screening performance assessment. The consistency among different regions and thalassemia genotypes were also investigated.

RESULTS

Among the 2258 neonates, 485 were identified to have a likely diagnosis of thalassemia, and 422 α-thalassemia, 80 β-thalassemia, and 21 α/β-thalassemia cases were confirmed by molecular analysis, including 277 α-thalassemia silent carriers, 135 α-thalassemia trait carriers, 10 Hemoglobin H disease, and 80 β-thalassemia trait carriers. The screening sensitivity, specificity, positive, and negative predictive value for α-thalassemia and β-thalassemia were 84.83%, 99.14%, 95.98%, 96.41%, and 88.75%, 98.73%, 76.34%, and 99.48%, respectively. The optimized interpretation model showed higher performance for thalassemia carriers, though some neonates with silent α-thalassemia genotypes (-α^3.7 /αα, -α^4.2 /αα, and α^WS α/αα) and β^-28 /β^N genotype were still missed. The screening performance among different regions was comparable.

CONCLUSIONS

Capillary hemoglobin electrophoresis with the optimized interpretation model shows reliable performance for newborn thalassemia screening. It is applicable to large-scale population screening.

Southeast Asian Ovalocytosis and Hemoglobinopathies in Newborns: Prevalence, Molecular, and Hematologic Analyses

OBJECTIVES

Southeast Asian ovalocytosis (SAO) is an inherited red blood cell (RBC) membrane disorder, whereas hemoglobinopathies are inherited globin gene disorders. In an area where both diseases are prevalent, the interaction between them resulting in variable hematologic parameters can be encountered. However, little is known about the genetic interaction of SAO and thalassemia. We investigated the prevalence of SAO and hemoglobinopathy genotypes among newborns in southern Thailand.

PATIENTS AND METHODS

This study was carried out on 297 newborns recruited consecutively at Naradhiwas Rajanagarindra Hospital in the south of Thailand. The SAO was identified on blood smear examination and polymerase chain reaction analysis. Thalassemia genotypes were defined. Hematologic parameters and hemoglobin (Hb) profiles were recorded and analyzed.

RESULTS

Among 297 newborns, 15 (5.1%) carried SAO, whereas 70 (23.6%) had thalassemia with 15 different thalassemia genotypes. Abnormal Hb including Hb C, Hb Q-Thailand, and Hb D-Punjab were observed in 5 newborns. It was found in the nonthalassemic newborns that RBC count, Hb, and hematocrit of the nonthalassemic newborns with SAO were significantly lower than those without SAO. The same finding was also observed in the thalassemic newborns; RBC count, Hb, and hematocrit of the thalassemic newborns with SAO were significantly lower than those without SAO. However, the mean corpuscular volume, mean corpuscular Hb, and RBC distribution width of the SAO-newborns were significantly higher.

CONCLUSIONS

Both SAO and hemoglobinopathy genotypes are common in southern Thailand. One should take this into consideration when evaluating neonatal anemia and other hematologic abnormalities. Identification of both genetic defects and long-term monitoring on the clinical outcome of this genetic interaction should be essential to understand the pathogenesis of these common genetic disorders in the region.

Fluorescence spectroscopy as a novel technique for premarital screening of sickle cell disorders

Spectral diagnostic screening for sickle cell disease was carried out on volunteer blood samples (N = 100). The samples were subjected to different diagnostic methods including conventional complete blood count (CBC), hemoglobin electrophoresis (HBE) and spectral diagnosis. For the spectral diagnostic method, we discriminated three different characteristic spectral features. In total, 15 samples were sickle cell trait (SCT), 34 samples were sickle cell disease (SCD), and the rest of the samples (N = 51) were normal controls. The spectral discrimination of the three different sets of samples was distinguished on the quantification of fluorescent biomolecules such as tyrosine, tryptophan, NADH, FAD, and porphyrins. The results were compared with the conventional standard CBC and capillary electrophoresis findings. The spectral diagnosis method exhibited a sensitivity and specificity greater than 90 % for the tested samples. This technique requires only 5 mL blood samples, has an analysis time of 20 min, exhibits high accuracy and may be used in small clinics in remote villages.

Hb Athens-Georgia (beta 40(C6) Arg > Lys, HBB:c.122G > A) with a single α-globin gene (Hb H disease) in a Thai family: molecular, hematological, and diagnostic aspects

Interaction of structural hemoglobin (Hb) variants with α- or β-globin defects are occasional in Southeast Asia. Herein we provide the first description of Hb Athens-Georgia (Hb A-Ga) in association with deletional Hb H disease, a novel combination previously undescribed in the population. Hematological, Hb and DNA analysis, and β-globin haplotype analyses were performed in seven participants from one ethnic Thai family. Hemoglobin analysis by capillary electrophoresis revealed an abnormal Hb fraction in the proband, his father and grandmother (I-2). DNA sequencing revealed that the G > A substitution at codon 40 of the β-globin gene was identical to the Hb A-Ga (HBB:c.122G > A). Interestingly, α-thal-1 (SEA deletion) and α-thal-2 (-α^3.7 deletion) were identified in the proband resulting in Hb H disease, while α-thal-1 was identified in the father, and no α-thal was observed in I-2. Hematological analysis indicated that the proband (β^A-Ga/β^A, -^SEA/-α^3.7) had moderate anemia and was markedly hypochromic with microcytic red blood cells (RBCs). The father (β^A-Ga/β^A, -^SEA/αα) presented mild microcytic anemia, while normal hematology was observed in the I-2 who was heterozygous for Hb Athens-Georgia (β^A-Ga/β^A, αα/αα). The relative level of Hb A-Ga was distinctly reduced according to the degree of α-globin defects. The developed allele-specific PCR method can successfully be used for confirmation of Hb A-Ga. The Thai Hb A-Ga allele associated with a β-haplotype [+ - - - - - +]. These findings were in accordance with the previous conclusion that this variant is a non-pathological β-Hb variant.

Prevalence of Alpha(α)-Thalassemia in Southeast Asia (2010-2020): A Meta-Analysis Involving 83,674 Subjects

Alpha(α)-thalassemia is a blood disorder caused by many types of inheritable α-globin gene mutations which causes no-to-severe clinical symptoms, such as Hb Bart's hydrops fetalis that leads to early foetal death. Therefore, the aim of this meta-analysis was to provide an update from year 2010 to 2020 on the prevalence of α-thalassemia in Southeast Asia. A systematic literature search was performed using PubMed and SCOPUS databases for related studies published from 2010 to 2020, based on specified inclusion and exclusion criteria. Heterogeneity of included studies was examined with the I2 index and Q-test. Funnel plots and Egger's tests were performed in order to determine publication bias in this meta-analysis. Twenty-nine studies with 83,674 subjects were included and pooled prevalence rates in this meta-analysis were calculated using random effect models based on high observed heterogeneity (I2 > 99.5, p-value < 0.1). Overall, the prevalence of α-thalassemia is 22.6%. The highest α-thalassemia prevalence was observed in Vietnam (51.5%) followed by Cambodia (39.5%), Laos (26.8%), Thailand (20.1%), and Malaysia (17.3%). No publication bias was detected. Conclusions: This meta-analysis suggested that a high prevalence of α-thalassemia occurred in selected Southeast Asia countries. This meta-analysis data are useful for designing thalassemia screening programs and improve the disease management.

Prevalence of Thalassemia among Newborns: A Re-visited after 20 Years of a Prevention and Control Program in Northeast Thailand

Background

To provide accurate prevalence information of thalassemia in northeast Thailand, authors performed thalassemia screening in newborns after 20 years implementation of a prevention and control program.

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 α- 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 (52.6%) cases with as many as 22 different genotypes. The most prevalent one was Hb E (39.1%). The incidence of 3.1% α⁰-thalassemia, 25.9% α⁺-thalassemia, 5.4% Hb Constant Spring and 1.4% of Hb Paksé were encountered. Heterozygous β-thalassemia was found in 2 cases (0.6%). Hb capillary electrophoresis could demonstrate Hb E in all cases with Hb E and detected different levels of Hb Bart’s for different α-thalassemia genotypes but not in all cases with α-thalassemia. No newborn with severe thalassemia diseases was encountered.

Conclusion

This study reveals that α-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.

Haematological and electrophoretic characterisation of β-thalassaemia in Yunnan province of Southwestern China

OBJECTIVES

β-Thalassaemia is widely found in Southwestern China. Characterisation of β-thalassaemia can improve screening and prenatal diagnosis for at-risk populations.

DESIGN

A retrospective study.

METHODS

In this study, the levels of haemoglobin alpha 2 (HbA₂) and haemoglobin alpha (HbA) were analysed by gender for a total of 15 067 subjects screened by capillary electrophoresis. The cut-off value with the highest accuracy was established to identify β-thalassaemia in 723 patients suspected to have this disease. Haematological and electrophoretic characterisation of eight common types of β-thalassaemia were analysed in 486 β-thalassaemia subjects.

RESULTS

HbA levels were significantly higher in men than in women, but there was no significant difference on HbA₂ levels. A new cut-off value for the diagnosis of β-thalassaemia (HbA₂≥4.0%) with the highest accuracy was proposed for the studied populations. Haemoglobin (Hb) was significantly higher in men compared with women (p<0.05), whereas no statistically significant differences were found for mean cell volume (MCV), mean cell haemoglobin (MCH), HbA and HbA₂. The haemoglobin E (HbE) group showed comparatively higher values for haematological indices (Hb, MCV and MCH) than the other genotypes in heterozygous β-thalassaemia groups (p<0.05), and -28 (A>G) (HBB (β-globin):c.-78A>C) had significantly higher HbA₂ values compared with other β-thalassaemia.

CONCLUSIONS

Ethnic groups have diversified β-globin gene mutations and considerable haematological variations. Our study will lay the foundation for screening programmes and clinical management of thalassaemia in Southwestern China.

Relationship among glucose-6-phosphate dehydrogenase (G-6-PD) activity, G-6-PD variants and reticulocytosis in neonates of northeast Thailand

BACKGROUND

Misdiagnosis of G-6-PD deficiency in neonates, at risk of severe hemolytic episodes, extreme hyperbilirubinemia, and bilirubin encephalopathy, could possibly occur due to presence of reticulocytes, which contain higher amounts of G-6-PD than mature erythrocytes. G-6-PD mutations in the population might also affect G-6-PD activity. This study evaluated the relationship among G-6-PD activity, G-6-PD variants and reticulocytosis in northeastern Thai neonates.

METHODS

Blood samples obtained from routine fluorescence spot test examination for G-6-PD deficiency were analyzed using a quantitative enzymatic assay and for common G-6-PD mutations by restriction fragment length polymorphism (RFLP)-PCR. Correlation between G-6-PD activity and percent reticulocytosis was determined.

RESULTS

Among 106G-6-PD-deficient (G-6PD activity<7.0U/g Hb) neonates, no significant association is observed between G-6PD activity and percent reticulocytosis (r=0.125, p-value=0.201), but there is a weak correlation in G-6-PD-normal neonates (r=0.377, p-value=0.014). There is a high frequency of G-6-PD Viangchan in male hemizygous and female heterozygous G-6-PD-deficient and G-6-PD-normal neonates.

CONCLUSIONS

A high reticulocytosis does not bias measurements of enzyme activity in G-6-PD-deficient neonates. Also, G-6-PD activity varies among female heterozygous neonates, and G-6-PD mutation analysis provides a reliable method to detect G-6-PD deficiency.

Implementation of newborn screening for hemoglobin h disease in mainland china

Hemoglobin H disease is the most severe non-fatal form of α-thalassemia syndrome characterized by pronounced microcytic hypochromic hemolytic anemia. It is predominantly seen in Southeast Asia, the Middle East and the Mediterranean. Studies suggest that hemoglobin H disease is not as benign a disorder as previously thought. Newborn screening for hemoglobin H disease is especially appealing because the screening test is based on the detection of hemoglobin Bart's (γ4) that is only possible within the newborn period. In this study, we reported on a 4-year period of newborn screening program at a mainland Chinese hospital, which detected 35 babies with hemoglobin H disease in a total of 26 152 newborns. The overall prevalence for hemoglobin H disease among all newborns in southern China is ~1 in 1,000. These children need appropriate follow-up and potential comprehensive care during their growth and development.

Diagnosis and prevention of thalassemia

Thalassemia is the most common monogenic inherited disease worldwide and it affects most countries to various extents. This review summarizes the current approaches to phenotypic and genotypic diagnosis of thalassemia in clinical practice. Prevention strategies that encompass carrier screening, genetic counseling and prenatal diagnosis are discussed. The importance of public education and an awareness of a changing perception regarding this group of diseases are emphasized. It also addresses the impact of the rapidly increasing knowledge in disease severity modification by hemoglobin F (Hb F).

Diagnostic applications of newborn screening for α-thalassaemias, haemoglobins E and H disorders using isoelectric focusing on dry blood spots

Background

Neonatal screening for haemoglobin (Hb) disorders is a standard of care in several developed countries with the main objective to detect Hb S. Such practice has not been established in Thailand where α-thalassaemia and haemoglobin E (Hb E) are highly prevalent. Early identification of thalassaemias could be helpful and strengthen the programme for prevention and control for severe thalassaemias.

Methods

Data from isoelectric focusing (IEF) and Isoscan® for detecting types and amount (%) of each haemoglobin in 350 newborn’s dried blood spots were analysed and compared with the comprehensive genotype analysis by DNA studies as a gold standard.

Results

Based on genetic profiles, there were 10 different categories: (1) normal ( n = 227), (2) α+-thalassaemia trait ( n = 14), (3) α0-thalassaemia trait ( n = 13), (4) β0-thalassaemia trait ( n = 7), (5) Hb E trait ( n = 72), (6) Hb E trait with α0-thalassaemia or homozygous α+-thalassaemia ( n = 5), (7) Hb E trait with α+-thalassaemia trait ( n = 5), (8) homozygous Hb E ( n = 3), (9) homozygous Hb E with α0-thalassaemia trait ( n = 1) and (10) Hb H disease ( n = 3). The presence of Hb Bart’s and Hb E were used to identify cases with α-thalassaemia and Hb E, respectively. We set 0.25% of Hb Bart’s and 1.5% of Hb E as a cut-off level to detect α+-thalassaemia trait (sensitivity 92.86% and specificity 74.0%) and Hb E trait with 100% of both sensitivity and specificity for IEF diagnosis.

Conclusion

Although molecular diagnosis seems to be better for definitive diagnosis of thalassaemia syndromes at birth, however, using our reference range described herein, IEF can be applied in a resource-limiting setting with acceptable reliability.

Automated capillary electrophoresis in the screening for hemoglobinopathies

Hemoglobinopathies are genetic disorders of globin chains characterized by the decreased expression of α- or β-globin chains (thalassemias) or by the synthesis of an abnormal protein (hemoglobin variants in, e.g., sickle cell disease). The screening of most hemoglobinopathies relies, together with hematological results and clinical elements, on the separation and quantification of normal and abnormal hemoglobin fractions. Gel electrophoresis, isoelectric focusing, and HPLC have been the methods of choice for many years. For about 20 years, capillary electrophoresis has appeared as a strong alternative method. Since the early 2000s, automated instruments are commercially available for the analysis of Hb fractions in adult patients but also for neonatal screening.

Expanded newborn screening of inborn errors of metabolism by capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS)

Expanded newborn screening of inborn errors of metabolism (IEM) based on tandem mass spectrometry technology has emerged as one of the most successful preventative healthcare initiatives for presymptomatic diagnosis and treatment of rare yet treatable genetic diseases. However, confirmatory testing using methods with improved specificity is required in clinical laboratories to improve the positive predictive value for certain classes of IEMs due to their high rates of false positives. Here, we describe recent advances for comprehensive profiling of amino acids and acylcarnitines derived from dried blood spot extracts or plasma using capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) that allows for resolution of major isobaric/isomeric interferences without complicated sample handling. The integration of online sample preconcentration together with desalting in CE-ESI-MS enables the direct analysis of hydrophilic amino acids, surface-active acylcarnitines, as well as labile thiols under a single format when using a simple aqueous buffer electrolyte system.

Prevalence of anemia and underlying iron status in naive antiretroviral therapy HIV-infected children with moderate immune suppression

Anemia is common in HIV-infected children and iron deficiency is thought to be a common cause. This study investigates the prevalence of anemia, thalassemia, and underlying iron status in Thai and Cambodian children without advanced HIV disease to determine the necessity of routine iron supplementation. Antiretroviral (ARV)-naive HIV-infected Asian children aged 1-12 years, with CD4 15-24%, CDC A or B, and hemoglobin (Hb) ≥7.5 g/dl were eligible for the study. Iron studies, serum ferritin, Hb typing, and C-reactive protein were assessed. Anemia was defined as Hb <11.0 g/dl in children <5 years of age or <11.5 g/dl in children 5-12 years. We enrolled 299 children; 57.9% were female and the mean (SD) age was 6.3 (2.9) years. The mean (SD) CD4% and HIV-RNA were 20% (4.6) and 4.6 (0.6) log(10) copies/ml, respectively. The mean (SD) Hb and serum ferritin were 11.2 (1.1) g/dl and 78.3 (76.4) μg/liter, respectively. The overall iron deficiency anemia (IDA) prevalence was 2.7%. One hundred and forty-eight (50%) children had anemia, mostly of a mild degree. Of these, 69 (46.6%) had the thalassemia trait, 62 (41.8%) had anemia of chronic disease (ACD), 9 (6.1%) had thalassemia diseases, 3 (2.0%) had iron deficiency anemia, and 5 (3.4%) had IDA and the thalassemia trait. The thalassemia trait was not associated with increased serum ferritin levels. Mild anemia is common in ARV-naïve Thai and Cambodian children without advanced HIV. However, IDA prevalence is low; with the majority of cases caused by ACD. A routine prescription of iron supplement in anemic HIV-infected children without laboratory confirmation of IDA should be discouraged, especially in regions with a high prevalence of thalassemia and low prevalence of IDA.