HPLC studies in hemoglobinopathies

Screening and treatment of thalassemia

Thalassemia refers to a collection of inherited conditions that lead to the production of abnormal hemoglobin, resulting from defects in the synthesis of globin chains. Currently, there is no definitive cure for thalassemia; therefore, early screening for thalassemia is the focus of clinical research. In recent years, thalassemia screening technology has been continuously developed, leading to updates in screening methods and significant improvements in accuracy. Genetic testing and hemoglobin electrophoresis are more popular in high-resource areas, effectively reducing the birth rate of children with severe thalassemia. This review summarizes current research on thalassemia screening from the perspectives of premarital, prenatal, and neonatal screening. In addition, the latest research on treatment of thalassemia has been concluded from the induction of fetal hemoglobin to gene therapy.

Cord Blood Hematological Parameters of Fetuses Detected Different Thalassemia Genotypes in the Second Trimester of Pregnancy

Background

Hemoglobinopathies are the most common inherited diseases in humans resulting from impaired globin chain synthesis of hemoglobin. The progression of thalassemia rates is prevented with prenatal screening methods.

Aims

To evaluate the hematological parameters of α- and β-thalassemia and normal fetuses aged 17-25 weeks of gestation.

Study Design

A cross-sectional study.

Methods

Pregnant women who underwent cordocentesis in the second trimester because of the risk of having a baby with thalassemia were included in the study. Hematological indices and molecular DNA methods were analyzed from the cord blood samples of 129 women who were 17-25 weeks into pregnancy. The HPLC method was used for Hb fraction analysis. Amplification refractory mutation system, restriction enzyme analysis, multiplex polymerase chain reaction, and sequencing methods were used for the molecular analysis. Maternal contamination was eliminated by the short tandem repeat method.

Results

In total, 112 of the fetuses carry α- and β-thalassemia heterozygous or homozygous (α: 37, β: 58, mixed: 17) and 17 fetuses had a normal genotype for thalassemia. Significant differences in adult hemoglobin (HbA), fetal hemoglobin (HbF), Hb Barts, MCV, MCH, and RDW were detected in three groups compared with the normal group (p < 0.001, except for RBC, Hb, HCT, and MCHC). Differences in HbF, Hb Barts, MCV, MCH, and RDW were observed in the α-thalassemia groups compared with the normal group (p < 0.001). Among the five β-thalassemia subgroups, only HbA and RDW were different from the normal group (p < 0.001).

Conclusion

This study could be a good reference for future studies and prenatal diagnostic applications in emphasizing the importance of changes in the blood parameters of fetuses before molecular genotyping. These hematological data give valuable information to clinicians about the fetus to enlighten families in making appropriate decisions during prenatal diagnosis.

Thalassemia and Hemoglobinopathy Screening in Women Attending Antenatal Clinic at a Tertiary Care Center in Uttarakhand, India: A Re-look at the Laboratory Parameters Mandating High-Performance Liquid Chromatography Workup

INTRODUCTION

Thalassemia and hemoglobinopathies are the most common inherited hematological disorders. Of these, β thalassemia is the commonest disorder reported in India, followed by certain hemoglobinopathies encountered in different regions of the country. The data pertaining to the incidence of these disorders in the Uttarakhand region of India are sparse.

AIM AND OBJECTIVES

To ascertain the prevalence and spectrum of thalassemia/hemoglobinopathies amongst antenatal women in Uttarakhand. The study also aimed to analyze the ability of red cell indices in differentiating beta thalassemia trait (BTT) from mild iron deficiency anemia (IDA).

MATERIAL AND METHODS

A total of 460 pregnant women in the first trimester of pregnancy were screened by cation exchange high-performance liquid chromatography. Retention time and proportions of normal/abnormal hemoglobin peaks were documented in all cases. Hemoglobin A2 (HbA2) values of ≥4% were taken as a cut-off for diagnosing BTT. Blood samples were also collected for complete blood counts, reticulocyte counts, and serum ferritin. The ability of the various discriminatory indices to differentiate between IDA and BTT was also assessed.

RESULTS

The prevalence of BTT and hemoglobin D-Punjab trait amongst pregnant women was found to be 2.6% and 0.2%, respectively. RBC count, mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) were found to be moderately strong predictors of BTT, with an area under the curve of 0.860, 0.857, and 0.842, respectively, which were comparable to the discriminatory indices found to be most useful in this study.

CONCLUSION

In view of the 2.6% prevalence of BTT in antenatal women in this region of Uttarakhand, a routine screening will be helpful in detecting carriers early in the antenatal period. Careful interpretation of red cell indices is crucial to the distinction between BTT and IDA. Discriminatory indices are reasonably accurate in differentiating BTT from mild iron deficiency, but for practical purposes, MCV and MCH provide equivalent information to identify cases that require further workup.

Clinical Presentation of Hemoglobin C in Albania: Case Series

The presence of HbC is a rare event in Europe and Mediterranean region where thalassemia and HbS are more frequently encountered. The rarely diagnosed cases are linked with the migration from West-Central Africa. Albania is one of the Mediterranean countries where inherited haemoglobin disorders are considerably widespread. Studies have shown the presence of thalassemia, sickle cell disease and sporadic cases of Hb O-Arab, Hb Lepore especially in the areas where malaria has been endemic. In 2006 we identified the first case with HbSC disease and until 2020 we have found 15 cases with HbC variant. In this study we have collected and analyzed the laboratory and clinical data of HbC cases. Our data support reports that HbC combinations with HbS and beta thalassemia are clinically important. Our data confirm the presence of the HbC variant in ex-malaric areas where thalassemia and HbS are quite widespread. 

Reactivation of γ-globin expression using a minicircle DNA system to treat β-thalassemia

Reactivation of fetal hemoglobin by editing the B-cell lymphoma/leukemia 11A (BCL11A) erythroid enhancer is an effective gene therapy for β-thalassemia. Using the CRISPR/Cas9 system, fetal γ-globin expression can be robustly reactivated to mitigate the clinical course of β-thalassemia. In our study, we found that the transfection efficiencies of CD34+ hematopoietic stem/progenitor cells (HSPCs) were significantly and negatively correlated with the length of plasmids and greatly affected by the linearization of plasmids. Furthermore, the transgene expression of minicircles (MC) without plasmid backbone sequences was better both in vitro and in vivo compared with conventional plasmids. Thus, MC DNA was used to deliver the cassette of Staphylococcus aureus Cas9 (SaCas9) into HSPCs, and a single-guide RNA targeting the erythroid enhancer region of BCL11A was selected. After electroporation with MC DNA, an evident efficiency of gene editing and reactivation of γ-globin expression in erythroblasts derived from unsorted HSPCs was acquired. No significant off-target effects were found by deep sequencing. Furthermore, fragments derived from lentiviral vectors, but not MC DNA, were highly enriched in promoter, exon, intron, distal-intergenic, and cancer-associated genes, indicating that MC DNA provided a relatively safe and efficient vector for delivering transgenes. The developed MC DNA vector provided a potential approach for the delivery of SaCas9 cassette and the reactivation of γ-globin expression for ameliorating syndromes of β-thalassemia.

Significance of borderline HbA2 levels in β thalassemia carrier screening

Increased HbA₂ levels are the characteristic feature of β-thalassemia carriers. A subset of carriers however do not show HbA₂ levels in the typical carrier range (≥ 4.0%) but show borderline HbA₂ levels. As a result, these carriers escape diagnosis and carry the risk of having β-thalassemia major offspring. Borderline HbA₂ values may occur as a consequence of mild β-thalassemia mutations, co-inherited β-thalassemia and α- or δ- thalassemia or iron deficiency anemia. However, there is insufficient knowledge regarding the cause of borderline HbA₂ levels in specific populations. This study aimed to identify the determinants of borderline HbA₂ levels (which we have considered as HbA₂ 3.0–3.9%) in 205 individuals. Primary screening involved detecting the presence of iron deficiency anemia followed by molecular analysis of α, β and δ globin genes. Remarkably, 168 of 205 individuals were positive for a defect. 87% (149/168) of positive individuals were heterozygous for β thalassemia with (59/149) or without (90/149) the presence of co-existing IDA, α or δ gene defects. Notably, 20 of 149 β thalassemia carriers showed HbA₂ < 3.5% and MCV > 80fL. 7 of these 20 carriers were married to carriers of hemoglobinopathies. Our findings describe the genetic basis of borderline HbA₂ levels and emphasize the necessity of a molecular diagnosis in these individuals in the routine clinical setting.

A portable impedance microflow cytometer for measuring cellular response to hypoxia

This article presents the development and testing of a low-cost (<$60), portable, electrical impedance-based microflow cytometer for single-cell analysis under a controlled oxygen microenvironment. The system is based on an AD5933 impedance analyzer chip, a microfluidic chip, and an Arduino microcontroller operated by a custom Android application. A representative case study on human red blood cells (RBCs) affected by sickle cell disease is conducted to demonstrate the capability of the cytometry system. Impedance values of sickle blood samples exhibit remarkable deviations from the common reference line obtained from two normal blood samples. Such deviation is quantified by a conformity score, which allows for the measurement of intrapatient and interpatient variations of sickle cell disease. A low conformity score under oxygenated conditions or drastically different conformity scores between oxygenated and deoxygenated conditions can be used to differentiate a sickle blood sample from normal. Furthermore, an equivalent circuit model of a suspended biological cell is used to interpret the electrical impedance of single flowing RBCs. In response to hypoxia treatment, all samples, regardless of disease state, exhibit significant changes in at least one single-cell electrical property, that is, cytoplasmic resistance and membrane capacitance. The overall response to hypoxia is less in normal cells than those affected by sickle cell disease, where the change in membrane capacitance varies from -23% to seven times as compared with -17% in normal cells. The results reported in this article suggest that the developed method of testing demonstrates the potential application for a low-cost screening technique for sickle cell disease and other diseases in the field and low-resource settings. The developed system and methodology can be extended to analyze cellular response to hypoxia in other cell types.

Borderline HbA2 levels: Dilemma in diagnosis of beta-thalassemia carriers

There is inconsistency in the exact definition of diagnostic levels of HbA₂ for β thalassemia trait. While many laboratories consider HbA₂ ≥4.0 % diagnostic, still others consider HbA₂ ≥3.3 % or HbA₂ ≥3.5 % as the cut-off for establishing β thalassemia carrier diagnosis. This is because, over the years, studies have described β thalassemia carriers showing HbA₂ levels that lie above the normal range of HbA₂ but below the typical carrier range of β thalassemia. These, "borderline HbA₂ levels", though not detrimental to health, are significant in β thalassemia carrier diagnosis because they can lead to misinterpretation of results. In this review, we have evaluated the prevalence of borderline HbA₂ levels and discussed the causes of borderline HbA₂ values. We have also compiled an extensive catalogue of β globin gene defects associated with borderline HbA₂ levels and have discussed strategies to avoid misdiagnosing borderline HbA₂ β thalassemia carriers. Our analysis of studies that have delineated the cause of borderline HbA₂ levels in different populations shows that 35.4 % [626/1766] of all individuals with borderline HbA₂ levels carry a molecular defect. Among the positive samples, 17 % [299/1766] show β globin gene defects, 7.7 % [137/1766] show α thalassemia defects, 2.7 % [49/1766] show KLF1 gene mutations, 2.3 % [41/1766] show the co-inheritance of β and α thalassemia, 2.0 % [37/1766] show the co-inheritance of β and δ thalassemia and 1.8 % [32/1766] show α globin gene triplication. It appears that a comprehensive molecular work up of the β globin gene is the only definite method to detect borderline HbA₂ β thalassemia carriers, especially in populations with a high prevalence of the disease. The presence of associated genetic or acquired determinants may subsequently be assessed to identify the cause of borderline HbA₂.

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.

Spectrum of hemoglobin disorders in southern Odisha, India: a hospital based study

Background:

Hemoglobin disorders are the leading health concern in the world including India. There is a paucity of literature on the spectrum of hemoglobin disorders in southern districts of Odisha state. This study was undertaken to elucidate the occurrence of different hemoglobin disorders in a tertiary health care facility of Odisha state, India.

Methods:

The study cases were suspected patients of all age groups advised for screening of different hemoglobin disorders. Hemoglobin disorders were screened by sickling slide test and high-performance liquid chromatography (HPLC) using the Variant-II hemoglobin testing system as per the manufacturer's guidelines.

Results:

Over 2 years, 2332 blood samples (including 1102 pediatric and 1230 adult cases) were investigated, out of which, 1380 (59.2%) of cases had abnormal hemoglobin disorders. The most common was sickle cell disorders (48.67%, 1135/2332) followed by β-thalassemia (11.32%, 264/2332). Some rare variants were detected as hemoglobin D^-Punjab, hemoglobin E, hemoglobin Lepore, hereditary persistence of fetal hemoglobin, hemoglobin with high P2 window, hemoglobin with high P3 window etc, Among the cases with abnormal hemoglobin disorders, 744 (53.9%), 545 (39.5%) and, 91 (6.6%) cases were found to have the heterozygous, homozygous and, double heterozygous state. Of the 188 ante-natal cases screened, 31.4% of cases had abnormal hemoglobin variants with sickle cell disorders being the most prevalent one.

Conclusion:

Along with the high occurrence of sickle cell disorders in the study area, some other rare hemoglobin disorders are also prevalent which calls for a large community-based cohort study.

Application of HbA2 levels and red cell indices-based new model in the differentiation of thalassemia traits from iron deficiency in hypochromic microcytic anemia Cases

INTRODUCTION

Thalassemia traits and iron deficiency anemia are the most common types of hypochromic microcytic anemia with similar clinical and laboratory features. It is vital to establish a new screening model based on HbA₂ levels and red cell indices for the differentiation of TT from IDA in hypochromic microcytic anemia cases.

METHOD

The data comprised of the red blood cell indices and HbA₂ prenatal diagnostic test results of 810 individuals who were identified to conform to the following criteria: MCV < 80 fl or MCH < 26 pg. We launched a new model consisting mainly of significative red cell indices and HbA₂ levels, as well as proposing cutoff values by using decision trees and logistic regression analyses. Next, we evaluated our new method by comparing the sensitivity, specificity, positive, and negative predictive values with those of the previous formulas.

RESULTS

We put forward a new model and compared it with 5 efficient formulas. The new model exhibited the highest accuracy (0.918), with its sensitivity and specificity calculated as 0.917 and 0.921, respectively. Our new model's Youden index was 0.838, which is higher than the other formulas' Youden indices.

CONCLUSIONS

The new screening model, based on HbA₂ levels and red cell indices, is suitable for the screening of thalassemia patients in the hypochromic microcytic anemia group and has the best efficiency in distinguishing TT and IDA.

Emerging point-of-care technologies for sickle cell disease diagnostics

Sickle cell disease (SCD) is a serious and life-threatening disorder. SCD is considered a public health issue affecting 25% of the population in Central and West Africa. Some countries in this region lack the necessary resources to treat and diagnose many diseases including SCD. Current methods for screening SCD are time-consuming and require expensive laboratory equipment and facilities. This leads to an inability to diagnose the disease early. Lack of early diagnosis and treatment can lead to childhood death. The number of childhood deaths is significantly higher in developing countries. There is unmet need to develop novel methods for diagnosing and monitoring SCD that are both cost effective and portable. The point-of-care (POC) platforms provide the cost effectiveness and portability that allows for the potential diagnosis of millions of people in countries with few resources. In this review, we summarized the important features, benefits, limitations and potential of POC devices. We conducted a comprehensive literature analysis to compare the sensitivity and specificity of several POC diagnostics developed for SCD with a focus on their usages in resource limited settings.

Association of fetal hemoglobin level with frequency of acute pain episodes in sickle cell disease (HbS-only phenotype) patients

BACKGROUND

Sickle cell disease (SCD) is a Mendelian single gene disorder with highly variable phenotypic expression. In the present study, we analyzed the influence of HbF, alpha thalassemia and other hematological indices to determine their association with acute pain episodes.

METHOD

This case control study consisted of SCD subjects with HbS phenotype experiencing three or more acute pain episodes in last twelve months (cases) and without any episode of acute pain during last twelve months (controls). Hematological parameters, HbF, and presence of alpha thalassemia were assessed in all subjects.

RESULTS

A statistically significant difference between HbF levels (P < 0.025, χ2 test) and alpha thalassemia (P < 0.008, χ2 test) was observed between controls and cases group. Univariate analysis indicated that increased HbF levels > 25% (OR: 0.37, 95% CI: 0.18-0.77, P < 0.008) and presence of alpha thalassemia (OR: 0.53, 95% CI: 0.33-0.85, P < 0.009) provided protection, while multivariate analysis revealed significant protection was attributable only by higher HbF levels (OR: 0.39, 95% CI: 0.17-0.88, P < 0.025). Significantly higher HbF levels were observed only in the 11-20 age group of cases in comparison to controls (Student's t-test, P < 0.001).

CONCLUSION

Higher concentrations of HbF are associated with protection against frequent episodes of acute pain crisis in SCD patients.

A Novel Technique of Spectral Discrimination of Variants of Sickle Cell Anemia

Sickle cell anemia (SCA) is an inherited blood disorder with worldwide incidence of 15%; out of this, it is found in up to 20% in countries like Kingdom of Saudi Arabia and Bahrain. The standard conventional method of detection is complete blood count (CBC) followed by hemoglobin electrophoresis or high-performance liquid chromatography (HPLC) or both. In this context, spectral detection of variants of sickle cell anemia (SCA) is an innovative technique, which when made accurate and reliable could be an effective alternative, since the instrumentation is compact (5 kg) and hence portable. This makes mass screening even in remote villages possible. In this paper, we give the essential aspects of fluorescent spectral features of sickle cell trait (SCT), sickle cell disease (SCD), beta (β) thalassemia trait (BTT) + SCD, and beta (β) thalassemia disease (BTD) + SCD. All the above four major variants could be discriminated among themselves and also from the normal control blood sample. All these analyses could be carried out with 5 ml of blood, in a time period of 10 minutes. The results of this paper give strong support for an alternative method, a spectral technique, for molecular-level diagnosis of sickle cell anemia and other closely related blood disorders.

Prenatal Diagnosis of HbE-β-Thalassemia: Experience of a Center in Western India

The clinical presentation of HbE-β-thalassemia is extremely variable, however, many cases are severe and transfusion dependent. We offered prenatal diagnosis to 108 couples, 20 of whom came prospectively. CVS was done in 93 cases (9.5-13 weeks of gestation) while amniocentesis/cordocentesis was done for 15 cases in the second trimester. Diagnosis was done by reverse dot blot hybridization, ARMS, DNA sequencing and in a few cases by HPLC analysis of fetal blood. The genetic combinations in the couples at-risk were the following: HbE trait/β-thal trait-95, HbE-thal/HbE trait-5, HbE homozygous/β-thal trait-3, HbE-thal/β-thal trait-3, HbE Lepore/β-thal trait-1, HbE trait/HbD^Punjab trait-1. IVS1-5(G>C) was the commonest β-thalassemia mutation followed by codon15(G>A), codon30(G>C), codons41/42(-CTTT), the 619 bp deletion and codon8/9(+G) in the β-thalassemic parent. However, several rare mutations seen in India like -90(C>T), -88(C>T),codon15(-T), IVS1-129(A>C), IVS1-130(G>C), IVSII-1(G>A), IVSII-837(C>T) and IVSII 848(C>A) were also encountered. Twenty-one fetuses were affected (HbE-β-thal-20, β-thal major-1) and all the couples opted for termination of the pregnancies. Couples with affected children wish to undergo prenatal testing for HbE-β-thal in subsequent pregnancies. More regional centers are needed for these services, particularly in West Bengal and the North-East where HbE is very common.

Comparison of the characteristics of two hemoglobin variants, Hb D-Iran and Hb E, eluting in the Hb A2 window

Background

Cation exchange-high performance liquid chromatography (CE-HPLC) is most commonly used to evaluate hemoglobin (Hb) variants, which elute in the Hb A2 window. This study aimed to assess prevalence of an uncommon Hb variant, Hb D-Iran, and compare its red cell parameters and peak characteristics with those of Hb E that commonly elutes in the Hb A2 window.

Methods

Generally, we assess abnormal Hb using CE-HPLC as the primary technique along with alkaline and acid electrophoresis. All cases with Hb A2 window >9%, as assessed by CE-HPLCs during 2009–2013, were selected.

Results

Twenty-nine cases with Hb D-Iran variant were identified—25 heterozygous, 2 homozygous, 1 compound heterozygous Hb D-Iran/β-thalassemia, and 1 Hb D-Iran/Hb D-Punjab. Overall prevalence of Hb D-Iran was 0.23%. Compared to patients with Hb E, those with Hb D-Iran had significantly higher Hb (12.1 vs. 11.3 g/dL, P=0.03), MCV (82.4 vs. 76.4 fL, P=0.0044), MCH (27.9 vs. 25.45 pg, P =0.0006), and MCHC (33.9 vs. 33.3 g/dL, P=0.0005). Amount of abnormal Hb (40.7 vs. 26.4%, P=0.0001) was significantly higher while retention time (3.56 vs. 3.70 min, P=0.0001) was significantly lower in Hb D-Iran than in Hb E.

Conclusion

Hb D-Iran peak can be easily missed if area and retention time of the Hb A2 window are not carefully analyzed. To distinguish between variants, careful analysis of peak area and retention time is sufficient in most cases and may be further confirmed by the second technique—alkaline electrophoresis.

Capillarys 2 Flex Piercing: Analytical performance assessment according to CLSI protocols for HbA1c quantification

HbA_1c is used for monitoring diabetic balance. In this paper we report an assessment of the analytical performances of Capillarys 2 Flex Piercing (C2FP) for HbA_1c measurement using CE (Capillary Electrophoresis). CLSI (Clinical and Laboratory Standard Institute) protocols are used for the evaluation of apparatus performances: precision, linearity, method comparison, trueness and common interferences. HbA_1c CVs average in intra-assay was 1.6% between run imprecision CV ranged from 0.1 to 1.8%. The linearity was demonstrated between 4.7 and 15.0%. The comparison study revealed that Bland Altman plot mean difference was equal to -0.03 (CI 95% (-0.05 to -0.0003)) and Passing-Bablok regression intercept was -0.05, CI95%(-0.13 -  -0.05); slope: 1.00, CI95%[1.00-1.01]. A strong correlation (r > 0.99) was proved. No significant effects of hemoglobin variants were seen with CE on HbA_1c measurement. No problem related to sample-to-sample carry over was noted. No interferences of LA_1c and cHb were observed. CE allowed quantification of HbA_1c even at low level of total hemoglobin (40 g/L) in contrast to HPLC. Furthermore, this analyzer offered the opportunity of quantifying the HbA₂ simultaneously with HbA_1c . This evaluation showed that C2FP is a convenient system for the control of diabetes and the detection of hemoglobinopathies.

β-Thalassaemia and its Co-existence with Haemoglobin E and Haemoglobin S in Upper Assam Region of North Eastern India: A Hospital Based Study

INTRODUCTION

β-Thalassaemias are common genetic disorders in the Indian subcontinent and its status has not been well studied in the Upper Assam region of North Eastern India.

AIM

The aim of the study was to show the prevalence of β- thalassaemias and its co-existence with Haemoglobin E and Haemoglobin S in the Upper Assam region of North Eastern India.

MATERIALS AND METHODS

A total of 1200 anaemic patients were investigated for β- thalassaemias. Complete Blood Count (CBC) and High Performance Liquid Chromatography (HPLC) were done for screening.

RESULTS

Out of 1200 patients screened, 5.83% β-thalassaemia trait, 2.33% compound Hb E/β-Thalassaemia, 1.33% β-thalassaemia major and 0.42% compound Hb S/β- thalassaemia were detected. A high incidence of thalassaemia is found among the people of Upper Assam region of North Eastern India.

CONCLUSION

The only way to prevent the disease is carrier detection and awareness among the people about it.

Spectrum of hemoglobin variants in the population of northern region of west bengal: an ethnogenetic proposition

Context:

The birth of transfusion-dependent states of hemoglobinopathies including thalassemias is preventable by population screening and genetic counseling. Magnitude is not addressed in the Northern Region of West Bengal where many ethnic variants inhabit.

Aims and Objectives:

The aim of the following study is to find out the burden of different entities of hemoglobinopathies, their correlation with ethnicity and the “at risk” groups.

Subjects and Methods:

A descriptive study was conducted from the Hematology Unit of North Bengal Medical College over 1 year on the subjects underwent screening for hemoglobinopathies for detection of abnormal hemoglobin (Hb) variants by “cation-exchange high-performance liquid chromatography” principle along with other relevant tests.

Statistical Analysis:

Data was analyzed by frequency distribution and Chi-square test assuming P value as 95% of the level of significance using the SPSS version 16 (SPSS Inc., Chicago, Illinois, U.S.A).

Result:

Abnormal Hb variant was 47.5% among 1872. Hb E trait (34.4%) was most common followed by Hb E disease (25.3%) and others. Hb E disorders (92.7%) were observed mostly among Rajbangsi population while E-β-thalassemias (40%) in the Muslims and a heterogeneous pattern noted among tribal and mongoloid.

Conclusion:

Hb E hemoglobinopathies was high among Rajbangsi and Muslims with identification of some other hemoglobinopathies involving tribal and mongoloid.

Detection of Abnormal Hemoglobin Variants by HPLC Method: Common Problems with Suggested Solutions

Thalassemia and thalassemic hemoglobinopathies pose serious health problem leading to severe morbidity and mortality in Indian population. Plethora of hemoglobin variants is prevalent in multiethnic Indian population. The aim of the present study was to analyze laboratory aspects, namely, hematological profile and HPLC findings of the hemoglobin variants detected, and to discuss problems that we faced in diagnosis in a routine clinical laboratory. We screened a total of 4800 cases in a hospital based population of North India in a 2-years period of by automated HPLC method using the Variant Hemoglobin Testing System (Variant II Beta Thalassemia Short Program, Bio-Rad Laboratories) under the experimental conditions specified by the manufacturer. Whole blood in EDTA was used and red cell indices were determined using automated hematology analyzer. We detected 290 cases with abnormal variants in which beta thalassemia was the most common followed by hemoglobin E. Here, we discuss the laboratory aspects of various hemoglobin disorders and diagnostic difficulties in cases like borderline HbA2 values, presence of silent mutation, alpha thalassemia gene, and few rare variants which at times require correlation with genetic study. Special attention was given to HbA2 level even in presence of a structural variant to rule out coinheritance of beta thalassemia gene.

HPLC in characterization of hemoglobin profile in thalassemia syndromes and hemoglobinopathies: a clinicohematological correlation

High-performance liquid chromatography (HPLC) is a technique introduced for the accurate diagnosis of hemoglobinopathies and thalassemias. The advantage of the HPLC system is the excellent resolution, reproducibility & quantification of several normal & abnormal hemoglobin resulting in accurate diagnosis of thalassemia syndromes. The purpose of this study is to evaluate the HPLC technique in diagnosis of thalassemia syndromes and also correlate it with clinicohematological profile in these cases. A total of 110 cases were diagnosed as thalassemias and hemoglobinopathies by Bio- Rad variant II HPLC system by β-thal short program. The retention times, proportion of the haemoglobin (%), and peak characteristics for all hemoglobin (Hb) fractions were recorded. Alkaline Hb electrophoresis was performed in each case. Other tests performed were HbF estimation by Betke's method, brilliant cresyl blue preparation for HbH inclusion bodies, sickling tests using 2 % metabisulphite and serum Ferritin estimation. Family studies were carried out wherever necessary. Of 110 cases included in the study, 87 cases were of thalassemic disorders and 23 cases were of hemoglobinopathies. Four Hb variants were identified including HbD, HbE, HbS, HbJ Oxford. There was a significant decrease in the level of HbA2 associated with iron deficiency anemia. The mean HbA2 levels in both iron deplete and iron replete groups were clearly >4 %, suggesting that HPLC identified nearly all high HbA2 β-thalassemia trait even in spite of iron deficiency.

Evaluation of high performance liquid chromatography (HPLC) pattern and prevalence of beta-thalassaemia trait among sickle cell disease patients in Lagos, Nigeria

Introduction

Sickle cell disease (SCD) is the most common inherited disorder of haemoglobin worldwide. This study evaluated the chromatographic patterns and red blood cell indices of sickle cell patients to determine the co-inheritance of other haemoglobin(Hb) variants and β-thalassaemia trait.

Methods

Red cell indices, blood film, sickle solubility test, Hb electrophoresis using alkaline cellulose acetate membrane, and chromatographic patterns using Bio Rad HPLC Variant II were evaluated for 180 subjects.

Results

Based on low MCV <76fL and MCH<25 pg, in the presence of elevated A₂ >4.0% on HPLC and Hb variants eluting outside the S and C windows, at least four haemoglobin phenotypes (SS: 87.7%; SC: 1.1%; SD Punjab: 0.6%; Sβ-thalassemia: 10.6%) were identified. Mean Hb F% was 8.1±5.1 (median 7.65) for Hb SS and 6.03±5.2 (median 3.9) for Hb Sβ-thalassemia trait. Majority of Hb SS (69.1%) had Hb F% less than 10 while 27.6% had 10-19.9 and 3.2% had ≥ 20. Mean Hb F% was higher in female Hb SS (9.55±5.09; mean age 7.4±3.8 years) than the males (7.63±4.80; mean age 6.9±3.8 years) (P=0.02). A borderline significant negative correlation between age and Hb F levels among Hb SS subjects (r= -0.169 P=0.038) was also observed.

Conclusion

Our data suggests that α and β- thalassaemia traits, and other haemoglobin variants co-exist frequently with SCD in our population

Spectral detection of thalassemia: a preliminary study

Background

Thalassemias (Thal) are forms of inherited autosomal recessive blood disorders arising out of mutations in the chromosomes 11 or 16. These disorders lead to poor oxygen delivery to blood vessels and consequent splenomegaly, bone deformities, and shorter life spans. The most common detection methods for Thal are complete blood count (CBC) followed by electrophoresis and molecular diagnosis methods, such as high-performance liquid chromatography (HPLC) and polymerase chain reaction (PCR) genotyping. These methods involve sophisticated instrumentations and are cumbersome and expensive.

Results

In this study an innovative spectral detection method, based on the fluorescence spectra of a set of biomolecules (tyrosine, tryptophan, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide and porphyrins) found in blood components is presented. An algorithm based on the spectral features of such biomolecules of blood components of 20 Thal patients (10 female and 10 male) and 18 age adjusted normal controls (4 female and 14 male) demonstrate reasonable level of classification with sensitivity and specificity values exceeding 90%.

Conclusion

This new technique could be of significant value for Thal detection, diagnosis, and subsequent genetic counselling and could be adapted for use in small primary health centres.

The Prevalence of Factor V Leiden (G1691A) and Methylenetetrahydrofolate Reductase C677T Mutations in Sickle Cell Disease in Western India

The prevalence of the Factor V Leiden (FVL; G1691A) mutation and the methylenetetrahydrofolate reductase (MTHFR; C677T) mutation was determined in 180 patients with sickle cell (SS) disease (126 sickle homozygous and 54 sickle β-thalassaemia—age 1-47 years) and in 130 healthy controls. The FVL mutation in the heterozygous state was present in only 3 patients with SS disease and was absent in the controls. Genotyping of MTHFR 677C > T revealed increased frequency of the C allele than the T allele in patients as well as in controls. This suggests that these genetic markers may not be major risk factors for a hypercoagulable state in Indian patients with SS disease.

Prenatal diagnosis of haemoglobinopathies: our experience of 523 cases

BACKGROUND

We performed counselling for prenatal diagnosis (PD) of haemoglobinopathies in 372 couples. Thirty-four out of 372 (9.1%) did not undergo PD: six due to spontaneous abortion; nine because it was too difficult to make a decision if PD was positive; 18 because counselling excluded the carrier status of one or both parents; and one because parental mutations were mild.

METHODS

Eleven out of 338 (3.3%) couples underwent PD because they had a thalassaemic child; 106 (31.4%) were found to be at high risk during pre-conceptional screening; 221 (65.4%) because of familiarity. Of 523 PDs in 486 (92.9%), including six dichorionic twin pregnancies, PD was performed on DNA from chorionic villi (CV), and in 37 from amniocytes (7.1%). In 1/523 cases, PD was not completed because DNA from CV was not sufficient; in two cases single tandem repeat analysis revealed maternal contamination of foetal DNA; in 7/522 (1.3%) cases PD revealed non-paternity. In 435/522 (83.3%) cases, PD was performed using reverse dot-blot and ARMS; 34/522 (6.5%) required sequencing. In 53/522 (10.2%) cases it was necessary to test globin loci for large rearrangements.

RESULTS

One hundred and twenty out of 522 (23.0%) PDs revealed an affected foetus. In all but two cases the couple interrupted pregnancy. In the six twin pregnancies PD revealed a normal and a carrier foetus (two cases), carrier status in both foetuses (two cases) and a carrier and an affected foetus (two cases). In these latter cases the couple planned selective interruption.

CONCLUSIONS

Our PD procedure is successful and reliable, and is useful in high-risk areas characterised by molecular heterogeneity.

HbA2 levels in β-thalassaemia carriers with the Filipino β0-deletion: are the levels higher than what is found with non-deletional forms of β0-thalassaemia?

AIMS

Classical carriers of β-thalassaemia are identified by a raised HbA2 level. Earlier studies indicated that the Filipino β-deletion has high raised HbA2 levels. The introduction of automated high performance liquid chromatography (HPLC) for thalassaemia screening is an important advance in technology for haematology laboratories. The BioRad Variant II Hb analyser is a common instrument used to quantify HbA2 levels in thalassaemia screening. This study aimed to determine HbA2 levels in carriers of Filipino β-mutation using the BioRad Variant II Hb analyser.

METHODS

The Filipino β-deletion was identified using gap-polymerase chain reaction (PCR) in the parents of transfusion dependent β-thalassaemia patients who were homozygous for the Filipino β-deletion in the indigenous population of Sabah, Malaysia. Hb subtypes were quantified on the BioRad Variant II Hb analyser. Concurrent α-thalassaemia was identified by multiplex gap-PCR for deletions and amplification refractory mutation system (ARMS)-PCR for non-deletional mutations.

RESULTS

The mean HbA2 level for Filipino β-thalassaemia trait was 5.9 ± 0.47 and with coinheritance of α-thalassaemia was 6.3 ± 0.44 (-α heterozygous) and 6.7 ± 0.36 (-α homozygous). The HbA2 levels were all >4% in keeping with the findings of classical β-thalassaemia trait and significantly higher than levels seen in non-deletional forms of β-thalassaemia.

CONCLUSION

The HbA2 level measured on the BioRad Variant II Hb analyser was lower than the level in the first description of the Filipino β-thalassaemia. β-thalassaemia trait with coinheritance of α-thalassaemia (-α) is associated with significantly higher HbA2 level.

Prevalence and hematological profile of β-thalassemia and sickle cell anemia in four communities of Surat city

BACKGROUND

From the data of transfusion-dependent thalassemia major cases, the 4 communities (Muslim, Dhodia Patel, Kachhiya Patel, and Modh Bania) with high prevalence but not studied methodically were selected.

AIM

The aim of this study is to find prevalence of β-thalassemia and sickle cell anemia in 4 selected communities and also to evaluate hematological profile in them.

MATERIALS AND METHODS

For screening of β-thalassemia trait (BTT) and sickle cell trait (SCT), all samples were tested for red cell indices, solubility, HbA(2) level and doubtful cases confirmed on HPLC.

STATISTICAL ANALYSIS

Mean ± SD, χ(2) and 't' tests were used to evaluate the significance.

RESULTS AND CONCLUSION

Among 4 selected communities, the highest prevalence of BTT was observed in Modh Bania (6.2%) and Kachhiya Patel (6.05%) and that of SCT in Dhodia Patel (14.0%). Significantly higher prevalence of BTT was observed in Memon (P < 0.0001) and of SCT in Khalifa 6.6% (P < 0.0001) compared to other Muslim sub castes. Anemia was more prevalent in BTT compared to non-BTT and non-SCT subjects. 80% of Dhodia Patel non-BTT and non-SCT subjects showed microcytic red cell morphology. Their Mean ± SD Hb concentration was 12.1 ± 1.73, hence iron deficiency cannot be a sole reason. This community needs α-thalassemia and iron studies.

Is the poly A (T>C) mutation a causative factor for misdiagnosis in second trimester prenatal diagnosis of β-thalassemia by fetal blood analysis on high performance liquid chromatography?

We report the problems in diagnosis faced by two families referred for prenatal diagnosis of thalassemia where cordocentesis and fetal blood analysis by high performance liquid chromatography (HPLC) had to be done. The Hb A levels of the fetal blood measured by HPLC on the VARIANT™ Hemoglobin Testing System were 1.2 and 6.7%, respectively, suggestive of a heterozygous β-thalassemia (β-thal) fetus in the first case and a normal fetus in the second case. In one family, one of the parents had a borderline Hb A(2) level and in the other, one parent had normal RBC indices. However, DNA sequencing, done later, showed that in the first case the fetus was a compound heterozygote for the IVS-I-5 (G>C) and the polyadenylation signal site [poly A (T>C)] mutation, while in the second case, the fetus was homozygous for the poly A mutation. This emphasizes that characterization of β-thal mutations must be done whenever one of the parents has a borderline Hb A(2) level or normal RBC indices, and one should not rely on fetal blood analysis by HPLC for prenatal diagnosis of β-thal so as to avoid misdiagnosis.

Hemoglobin J--as a cause of congenital hemolytic anemia

Hemoglobin-J is a rare hemoglobin variant known to be clinically silent most of the times, only to be detected accidentally. Herein, the authors report a case of Hemoglobin-J manifesting as unstable hemoglobin detected during evaluation of hemolytic anemia in an 8 month-old-infant. Cation Exchange-High Performance Liquid Chromatography(CE-HPLC) was used to identify this variant after Hb electrophoresis was reported to be normal.

β-Thalassemia mutations in subjects with borderline HbA₂ values: a pilot study in North India

BACKGROUND

Interpreting hemoglobin high performance liquid chromatograms with borderline HbA₂ values is often problematic, especially in antenatal cases if the partner is a known thalassemia trait.

METHODS

We tested for underlying β-thalassemia mutations in 25 subjects with borderline HbA₂ values (between 3.0%-4.0%). Amplification refractory mutation system (ARMS-PCR) was used to detect the five common Indian β-thalassemia mutations: (IVS-I-5 (G>C), IVS-I-1 (G>T), codons 8/9 (+G), codons 41/42 (-TTCT) and 619 bp deletion). β-Globin gene sequencing was performed if no mutation was detected.

RESULTS

A β-globin gene defect was identified in 8 (32%) of the 25 cases with HbA₂ levels ranging from 3.5%-3.9%. ARMS-PCR revealed IVS-I-5 (G>C) in three, 619 bp deletion in two and codons 41/42 (-TTCT) in one case. Two cases had CAP +1 (A>C) mutation on gene sequencing. IVS-I-1 (G>T) and codons 8/9 (+G) were not found in this small cohort.

CONCLUSIONS

Mutation analysis should be offered to all at-risk couples with borderline HbA₂, especially those with values between 3.5% and 4.0% and microcytic hypochromic indices. Significant mutations different from those in other ethnic populations were seen in this small institution-based study.

Spectrum of haemoglobinopathies diagnosed by cation exchange-HPLC & modulating effects of nutritional deficiency anaemias from north India

Background & objectives:

The usefulness of cation exchange high performance liquid chromatography (CE-HPLC) as a tool for detection of thalassaemia/haemoglobin variants was evaluated in a prospective study in a tertiary care centre in north India. We also tried to evaluate the effect of concurrent nutritional deficiency on the HPLC pattern in the local ethnic population.

Methods:

A total of 800 blood samples were analyzed on the Bio-Rad Variant HPLC system by β-thal short program. The retention times, proportion of the haemoglobin (%), and the peak characteristics for all haemoglobin fractions were recorded. Alkaline and acid haemoglobin electrophoresis was performed to document the identities of the haemoglobin variants, wherever necessary. Many cases were subjected to family studies for a definitive diagnosis.

Results:

Among 800 samples tested, 553 (69.1%) were found to have normal HPLC pattern. Apart from β- thalassaemia, nine additional variants were encountered; HbS (2.8%), HbE (2.5%) and HbD (1.1%) being the most common variants present. Other variants included Hb Q-India, Hb-Lepore, δβ-thalassemia/ HPFH, HbD-Iran, HbJ-Meerut and HbH disease. There was a significant decrease in the level of HbA₂ associated with iron deficiency anaemia (IDA) (P=0.004) and increase in megaloblastic anaemia (P<0.001) among subjects with normal HPLC pattern.

Interpretation & conclusions:

HPLC was found to be a simple, rapid and reliable method for the detection of hemoglobin variants. An accurate diagnosis can be provided in majority of cases by use of retention time, proportion of total haemoglobin, and peak characteristics of HPLC. Haemoglobin electrophoresis and family studies play a valuable role in difficult cases. Concurrent nutritional deficiency also has an effect on HbA₂ levels.

Global burden, distribution and prevention of β-thalassemias and hemoglobin E disorders

The β-thalassemias, including the hemoglobin E disorders, are not only common in the Mediterranean region, South-East Asia, the Indian subcontinent and the Middle East but have now become a global problem, spreading to much of Europe, the Americas and Australia owing to migration of people from these regions. Approximately 1.5% of the global population are heterozygotes or carriers of the β-thalassemias. While the overall frequencies of carriers of these disorders are known in most countries, there have been few attempts at micromapping and wherever this has been done, significant variations are seen even within small geographic regions. Thus, the figures for the estimated numbers of births each year of homozygous β-thalassemia and the severe compound states involving other hemoglobin disorders may be an underestimate. Screening strategies have varied from premarital to antenatal in different countries depending on socio-cultural and religious customs in different populations. Prenatal diagnosis programs are ongoing in many countries and the knowledge of the distribution of mutations has facilitated the establishment of successful control programs. Many of these were through North-South partnerships and networking. Yet, there are many countries in Asia where they are lacking, and South-South partnerships are now being developed in South-East Asia and the Indian subcontinent to link centers with expertise to centers where expertise needs to be developed. Although the carrier frequencies will remain unaltered, this will eventually help to bring down the burden of the birth of affected children with β-thalassemias and hemoglobin E disorders in Asia.

Mutation analysis of the HBB gene in selected Bangladeshi beta-thalassemic individuals: presence of rare mutations

INTRODUCTION AND AIMS

Bangladesh has a large number of thalassemic patients. However, no extensive analysis of the mutations in the HBB gene of thalassemic patients has been previously carried out. We have conducted a systematic research to reveal thalassemia mutations in the Bangladeshi population. In this preliminary analysis of 587 bp of the HBB gene in selected thalassemic individuals, some rare mutations in world perspective have been found to be significantly high in the Bangladeshi population, together with the common mutations for thalassemia.

RESULTS

A 587-bp segment of the HBB gene from 32 chromosomes of 16 beta-thalassemic individuals was analyzed for molecular characterization of the disease. Splice junction mutation IVS-I-5 was found to be the most common. The analysis also revealed some rare mutations HBB: c.-80T>C, HBB: c. 92G>C, HBB: c-92C>G, which are not prevalent in geographically adjacent populations.

CONCLUSION

This is a first of this kind of study in the Bangladeshi population. Although the small sample size makes it difficult to make any population genetics inference, this study can be regarded as the seminal research for a large-scale study to determine the complete mutation profile underlying thalassemia in the Bangladeshi population. The complete mutation profile will provide invaluable strategies (e.g., prenatal diagnosis and genetic counseling) for better management of thalassemia in the Bangladeshi population.

Hb Tak and Hb Q-Thailand in Thai patients are S-window hemoglobin variants revealed by high performance liquid chromatography

The S-window hemoglobin (Hb) variants revealed by high performance liquid chromatography (HPLC) were studied in 12 Thai individuals. The variants were identified, using DNA sequencing and multiplex amplification refractory mutation system-polymerase chain reaction (ARMS-PCR), to be six cases of Hb Tak [beta147 (+AC)], and six cases of Hb Q-Thailand [alpha74(EF3)Asp-->His], respectively. By using the Capillarys 2-capillary zone electrophoresis (CE), Hb Tak and Hb Q-Thailand co-migrated with Hb F in zone 7. This might pose a problem as the high Hb F conditions suggest a differential diagnosis. The S-window Hb variants are mostly Hb Tak and Hb Q-Thailand in the Thai population rather than Hb S [beta6(A3)Glu-->Val]. The definite identification of Hb variants detected by HPLC or capillary electrophoresis (CE) requires DNA analysis.

SYTO9 and SYBR GREEN1 with high resolution melting analysis for molecular confirmatory testing of the common Southeast Asian beta(0)-thalassemia mutations

Gel electrophoresis and ethidium bromide staining are routine methods in molecular laboratories. However, they are not ideally suited to large scale analyses in clinical laboratories. We used SYTO9 and high resolution melting (HRM) analyses for identification of the common beta(0)-thalassemia (beta(0)-thal) in Southeast Asia including the codons 17 (A>T), 41/42 (-TCTT) and 71/72 (+A) mutations. Multiplex amplification refractory mutation system-polymerase chain reaction (MARMS-PCR) was performed on 102 blood samples that had Hb A(2) levels between 3.1 and 9.9%. The SYTO9 HRM analysis showed specific characteristic peaks of each investigated type of beta(0)-thal mutation. Results of MARMS-PCR followed by SYTO9 HRM analyses were completely consistent with results of those analyzed by gel electrophoresis. Moreover, the beta(0)-thal 3.5 kb gene deletion could be identified in two samples with Hb A(2) levels of >4% by GREEN1 HRM analysis. The SYTO9 and SYBR GREEN1 HRM analysis is simple and rapid. This approach will facilitate laboratory diagnosis and genetic counseling for regions with a high prevalence of beta-thal.

Prevalence of haemoglobinopathies in 34 030 healthy adults in Tehran, Iran

Background:

Haemoglobinopathies are a group of inherited disorders of haemoglobin synthesis. Their frequency varies considerably with geographic location and ethnic group.

Aims:

To establish the prevalence of haemoglobinopathies in a mainly healthy Iranian population.

Methods:

All files of the haematology unit of the Boghrat laboratory over a period of 10 years (1998–2007) were analysed in relation to the age, sex, full blood count, haemoglobin electrophoresis results, high performance liquid chromatography (HPLC) findings, and iron profile of healthy subjects referred for consultation before marriage. Other tests were performed if indicated.

Results:

There were 34 030 files; 13 432 (39.5%) were for men, and 20 567 (60.4%) for women. 0.74% of subjects (255) showed a haemoglobinopathy. The distribution of variant haemoglobins in these 255 subjects was: Hb D 75.67% (193 cases), Hb S 4.7%, Hb E 3.13%, Hb O-Arab 1.96% and Hb Lepore 0.39%. A fast haemoglobin was found in 4.71% of subjects. Of the subjects tested, 13.2% (4478) had β-thalassaemia minor, 0.2% (52) β-thalassaemia intermedia and 0.1% (30) β-thalassaemia major.

Conclusions:

In comparison with other parts of world, there is a different pattern of haemoglobinopathy with a high prevalence of Hb D, which appears to be Hb D Iran.