The range of hemoglobin A(2) in hemoglobin E heterozygotes as determined by capillary electrophoresis

Reliability of hemoglobin A2 value as measured by the Premier Resolution system for screening of β-thalassemia carriers

OBJECTIVES

Accurate quantification of hemoglobin (Hb) A2 is vital for diagnosing β-thalassemia carriers. This study aimed to assess the precision and diagnostic utility of HbA2 measurements using the new high-performance liquid chromatography (HPLC) method, Premier Resolution, in comparison to capillary electrophoresis (CE).

METHODS

We analyzed 418 samples, previously identified as A2A by CE, using Premier Resolution-HPLC. We compared the results, established correlations, and determined an optimal HbA2 cutoff value for β-thalassemia screening. Additionally, we prospectively evaluated the chosen cutoff value in 632 samples. Mutations in the β- and α-globin genes were identified using polymerase chain reaction (PCR) techniques and DNA sequencing.

RESULTS

HbA2 levels were consistently higher with Premier Resolution, yet there was a significant correlation with CE in all samples (bias, -0.33; r, 0.991), β-thalassemia (bias, -0.27; r, 0.927), and non-β-thalassemia carriers (bias, -0.36; r, 0.928). An HbA2 cutoff value of ≥4.0 % for β-thalassemia screening achieved 100 % sensitivity and 99.6 % specificity. Further validation yielded sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 97.3 , 99.8, 97.3, 99.8, and 99.7 %, respectively. We also identified a rare β-Hb variant, Hb La Desirade [HBB:c.389C>T], associated with β-thalassemia and co-inherited with a single α-globin gene.

CONCLUSIONS

The Premier Resolution HPLC is a reliable and accurate method for routine β-thalassemia carrier screening, aligning with existing CE methods.

Severe homozygous HbE disease: the first case report from Nepal

Hemoglobin E (HbE) is the most prevalent hemoglobinopathy in the eastern Indian subcontinent. We presented the case of a 53-year-old male from Nepal with a history of multiple blood transfusions who presented with abdominal fullness for 15 years and easy fatigability for 2 months. He had pallor and massive splenomegaly. Laboratory parameters showed pancytopenia with microcytic anemia, indirect hyperbilirubinemia, target cells in the peripheral smear and iron overload. A computed tomography scan of the abdomen showed multiple splenic infarcts. Hemoglobin electrophoresis was suggestive of HbE homozygous disease. Based on these findings, we made a diagnosis of HbE homozygous disease. We provided symptomatic treatment and folic acid supplementation and counseled him for splenectomy and genetic screening. Our case highlighted the uncommon presentation of Hb E disease.

PlyAB Nanopores Detect Single Amino Acid Differences in Folded Haemoglobin from Blood

The real‐time identification of protein biomarkers is crucial for the development of point‐of‐care and portable devices. Here, we use a PlyAB biological nanopore to detect haemoglobin (Hb) variants. Adult haemoglobin (HbA) and sickle cell anaemia haemoglobin (HbS), which differ by just one amino acid, were distinguished in a mixture with more than 97 % accuracy based on individual blockades. Foetal Hb, which shows a larger sequence variation, was distinguished with near 100 % accuracy. Continuum and Brownian dynamics simulations revealed that Hb occupies two energy minima, one near the inner constriction and one at the trans entry of the nanopore. Thermal fluctuations, the charge of the protein, and the external bias influence the dynamics of Hb within the nanopore, which in turn generates the unique ionic current signal in the Hb variants. Finally, Hb was counted from blood samples, demonstrating that direct discrimination and quantification of Hb from blood using nanopores, is feasible.

Hemoglobins F, A2 , and E levels in Laotian children aged 6-23 months with Hb E disorders: Effect of age, sex, and thalassemia types

Introduction

Determination of hemoglobins (Hbs) F, A_2, and E is crucial for diagnosis of thalassemia. This study determined the levels of Hbs F, A_2, and E in children aged 6‐23 months and investigated the effect of age, sex, and types of thalassemia on the expression of these Hbs.

Methods

A total of 698 blood samples of Laotian children including 272 non‐Hb E, 271 Hb E heterozygotes, and 155 Hb E homozygotes were collected. Hb profiles were determined using the capillary zone electrophoresis. Coinheritance of α‐thalassemia and the homozygosity for Hb E mutation were checked by PCR‐based assay.

Results

Children heterozygous and homozygous for Hb E had significantly higher Hb F and A₂ levels than non‐Hb E children (median Hb F = 1.1% for non‐Hb E group, 2.7% for Hb E heterozygotes, and 9.4% for Hb E homozygotes; median Hb A₂ = 2.6% for non‐Hb E group, 3.8% for Hb E heterozygotes, and 5.2% for Hb E homozygotes). The median Hb E levels were 21.9% for Hb E heterozygotes and 85.3% for Hb E homozygotes. Comparing within group, there was a statistically significant difference between children with and without an α‐gene defect for Hb A₂ and E, but not Hb F. Based on a multiple regression analysis, age and sex were significantly associated with the expression of Hb F and A₂ but not Hb E.

Conclusions

Our findings can guide the development of a diagnostic approach to thalassemia in children aged 6‐23 months.

Shine & Lal index as a predictor for early detection of β-thalassemia carriers in a limited resource area in Bandung, Indonesia

BACKGROUND

Thalassemia is the most common inherited disease in the world, involving α- or β-globin in red blood cells. Thalassemia cases rank fifth in the list of national catastrophic diseases in Indonesia; however, nationwide screening for thalassemia carriers is not yet mandatory. This study aimed to assess whether blood count metrics, such as the Shine & Lal index (SLI; MCV*MCV*MCH/100), might serve as a predictor to screen thalassemia carriers in a limited resource area where molecular methods are not readily available.

METHODS

During a family gathering of thalassemia patients, family members (n196) underwent a complete blood count test. Those with MCV < 80 fL and/or MCH < 27 pg and/or SLI < 1530 were further examined for Hb analysis. Only samples with HbA2 fraction > 4% or with a peak in the HbE fraction were sequenced to confirm β-globin gene mutations.

RESULTS

Of 196 family members, 117 (59.6%) had low MCV and/or low MCH and/or low SLI. The HbE fraction (mean 24.06% ± 0.95, range 22.4-26.5) was found in 27 (13.7%) cases, and all had a mutation at codon (CD)26 (c.79G > A). The mean HbA₂ fraction in these samples was 3.18% ± 0.62 (range 2.6-3.8). For samples with HbA2 > 4% (n30; 15.3%), all had mutations at IVS1nt5 (c.92 + 5 G > C; n28), CD8/9 (c.27_28insG; n1) and CD19 (c.59A > G; n1). The mean HbA₂ fraction with a mutation at IVS1nt5 (c.92 + 5 G > C) was 4.65% ± 0.77 (range 4.0-5.6). Interestingly, anaemia was only present in 25 and 57% of β-thalassemia carriers with mutations at CD26 (c.79G > A) and at IVS1nt5 (c.92 + 5 G > C), respectively.

CONCLUSIONS

The Shine & Lal index is helpful in the early screening of β-thalassemia carriers, since this index confirms mutations at CD-26 (c.79G > A) and at IVS1nt5 (c.92 + 5 G > C), which are both common mutations in Bandung, Indonesia. Further DNA analysis is a topic of interest to map variants in globin genes and their distribution across populations.

A Formula to Identify Potential Cases of β-Thalassemia/HbE Disease Among Patients With Absent HbA, HbE >75% and HbF Between 5 and 15

OBJECTIVE

To establish a simple formula to be used for discrimination between β-thalassemia/hemoglobin E (β-thal/HbE) and homozygous hemoglobin (Hb)E in specimens with absent hemoglobin (Hb)A, HbE of greater than 75%, and HbF between 5% and 15%.

METHODS

We analyzed laboratory results from February 2015 through February 2018. Molecular analysis for diagnosis of β-thal mutation and HbE was performed in specimens that contained HbE of greater than 75% and HbF from 5% to 15%, as measured by high-performance liquid chromatography (HPLC). HbA2 and HbF levels were also measured by capillary electrophoresis. Then, the formula (6 × HbA2 + HbF)/MCV was developed.

RESULTS

The score of 0.9 or higher was found in all 19 β-thal/HbE specimens (100%) and only 8 of 65 homozygous HbE specimens (12.3%). Also, the formula yielded 90.5% efficiency in identifying β-thal/HbE disease, and the efficiency was found to be higher compared with when the HbA2 value of greater than 6% was used by itself (85.4%).

CONCLUSION

The formula (6 × HbA2 + HbF)/MCV, with a cutoff point at 0.9, could identify the potential cases of β-thal/HbE disease among patients with absent HbA, HbE of greater than 75%, and HbF between 5% and 15%.

Evaluation of Thalassaemia Screening Tests in the Antenatal and Non-Antenatal Populations in Singapore

Introduction: Haemoglobinopathy testing is performed for carrier screening and evaluation of microcytic anaemia. We evaluated the effectiveness of thalassaemia screening tests at our institution and suggest ways of improving the testing algorithm. Materials and Methods: A total of 10,084 non-antenatal and 11,364 antenatal samples with alkaline gel electrophoresis (AGE), capillary electrophoresis (CE), haemoglobin H (HbH) inclusion test, mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) were retrospectively reviewed. A subgroup of 187 samples with genetic testing was correlated with HbH inclusions and MCH/MCV. The effect of iron deficiency on percentage haemoglobin A2 (HbA2) was studied. Results: HbH inclusion test showed low sensitivity of 21.43% for α-thalassaemia mutations but higher sensitivity of 78.95% for --SEA deletion. Byreceiver operating characteristic (ROC) analysis, MCH ≤28 pg or MCV ≤80 fl for non-antenatal samples and MCH ≤27 pg or MCV ≤81 fl for antenatal samples had >98% sensitivity for HbH inclusions. Above these thresholds, the probability that HbH inclusions would be absent was >99% (negative predictive value [NPV] >99%). MCH ≤28 pg had 100% sensitivity (95% CI 95.63%-100%) for α-thalassaemia mutations and 97.68% calculated NPV in the antenatal population. Detection of haemoglobin variants by CE correlated highly with AGE (99.89% sensitivity, 100% specificity). Severe iron deficiency reduced HbA2 in haemoglobin E (P <0.001) and α-thalassaemia (P = 0.0035), but not in β-thalassaemia. Conclusion: MCH/MCV thresholds have adequate sensitivity for α-thalassaemia in the antenatal population, and genotyping plays an important role as HbH inclusion test shows low sensitivity. CE without AGE, may be used as initial screening for haemoglobin variants. Our study provides contemporary data to guide thalassaemia screening algorithms in Singapore. Key words: Haemoglobinopathy, Mean corpuscular haemoglobin, Mean corpuscular volume

The shortcut strategy for beta thalassemia prevention

We propose antenatal blood tests using high-resolution DNA melting (HRM) analysis for beta thalassemia mutation detection after hemoglobin A₂ estimation as a modified strategy for the identification of beta thalassemia at-risk couples. Antenatal blood samples of 1,115 couples were transferred from the antenatal care clinic. Hemoglobin A₂ was quantified, and proportions ≥3.5% were further assessed for beta thalassemia mutation using HRM analysis. Twelve types of beta thalassemia mutations, including hemoglobin E, were identified. There were 23 couples who were detected as at-risk. All at-risk couples were identified within 7 working days after sample receipt. Prenatal diagnosis revealed 6 affected fetuses. One fetus was homozygous CD17 (AT), and five fetuses exhibited beta⁰ – thalassemia/hemoglobin E disease. These results were consistent with the outcomes calculated using the Hardy-Weinberg equation. Antenatal blood tests for mutation detection using high-resolution DNA melting analysis after hemoglobin A₂ estimation is a feasible laboratory method for the recruitment of couples with a fetus that is at risk for beta thalassemia. This modified strategy is cost-effective and may be beneficial for use in a beta thalassemia prevention program.

Sickle cell retinopathy: improving care with a multidisciplinary approach

Sickle cell retinopathy (SCR) is the most representative ophthalmologic complication of sickle cell disease (SCD), a hemoglobinopathy affecting both adults and children. SCR presents a wide spectrum of manifestations and may even lead to irreversible vision loss if not properly diagnosed and treated at the earliest. Over the past decade, multidisciplinary research developments have focused upon systemic, genetic, and ocular risk factors of SCR, enabling the clinician to better diagnose and manage these patients. In addition, newer imaging and testing modalities, such as spectral domain-optical coherence tomography angiography, have resulted in the detection of subclinical retinopathy related to SCD. Innovative therapy includes intravitreal injection of an anti-vascular endothelial growth factor (eg, Lucentis^® [ranibizumab] or Eylea^® [aflibercept]) which appears comparatively safe and efficient, and may be combined with laser photocoagulation (LPC) for proliferative SCR. The effect of LPC alone does not significantly lead to the regression of advanced SCR, although it helps in avoiding hemorrhage and sight loss. This comprehensive article is based on 10-years retrospective (2007–2017) studies. It aims to present advances and recommendations in SCR theranostics while pointing out the requirement of combinatorial approaches for better management of SCR patients. To reach this goal, we identified and analyzed randomized original and review articles, clinical trials, non-randomized intervention studies, and observational studies using specified keywords in various databases (eg, Medline, Embase, Cochrane, ClinicalTrials.gov).

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.

Unusual pattern in haemoglobin electrophoresis in Croatian population: a case report

Haemoglobinopathies are hereditary disorders of globin chain synthesis and are the most common inherited diseases worldwide. Haemoglobin E is a structural haemoglobin variant characteristic for South East Asian population. We present a rare and unusual finding of haemoglobin E detected in University Hospital Centre Zagreb by capillary zone electrophoresis. Detection of haemoglobin structural variant helped to avoid misdiagnosis of sideropenic anemia and thus potentially harmful therapeutic intervention. In today’s European multiethnic population haemoglobinopathies are a public health issue and Croatian laboratory professionals should be aware of a possibility of finding an unusual haemoglobin pattern.

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.

Hemoglobin E Hemoglobinopathy in an Adult from Assam with Unusual Presentation: A Diagnostic Dilemma

Hemoglobin E (HbE) is estimated to affect at least one million people around the world. Carrier frequency of hemoglobin E/β-thalassemia (HbE/β-thalassemia) is highest in Southeast Asia, reaching as high as 60% in parts of Thailand, Laos, and Cambodia. In the Indian subcontinent, highest frequency is observed in The Northeast regions, but relatively rare in rest of the country. Increasing migration of population from highly affected areas is resulting in rising prevalence in The South and other parts of India. HbE/β-thalassemia is characterized by marked clinical diversity, phenotypic instability, and age-related changes in adaptation to anemia. This paper reports a case of HbE disease in an adult immigrant from Assam and documents the difficulties encountered in the definitive subtyping of HbE hemoglobinopathy. Distinguishing between homozygous HbE disease and HbE/β-thalassemia is a challenge to hematopathologist as both are clinically and hematologically similar.

Modifying effect of XmnI, BCL11A, and HBS1L-MYB on clinical appearances: A study on β-thalassemia and hemoglobin E/β-thalassemia patients in Indonesia

OBJECTIVE/BACKGROUND

Thalassemia is a monogenic hematologic disease that has the highest prevalence globally. In addition, there is complexity of the genetic background associated with a variety of phenotypes presented among patients. Genetic heterogeneity related to fetal hemoglobin (HbF) production has been reported as an influencing phenotypic factor of β-thalassemia (β-thal). Therefore, this study aimed to find the effect of these genetic modifiers, especially in the XmnI locus, rs11886868, rs766432 (BCL11A), and rs9399137 (HBS1L-MYB), among β-thal and HbE/β-thal patients in Indonesia, according to laboratory and clinical outcomes, including HbF levels and clinical scores. This study was also designed to compare these modifying effects among β-thal and HbE/β-thal patients in Indonesia.

METHODS

A total of 189 patients with genotyping of β-thal and HbE/β-thal were included in this study. The erythrocytes index and Hb electrophoresis measurements were calculated using appropriate methods. The severity of β-thal and HbE/β-thal was classified based on the Mahidol score. Polymorphism of the XmnI locus, rs11886868, rs766432 (BCL11A), and rs9399137 (HBS1L-MYB) was determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and amplification refractory mutation system (ARMS) methods.

RESULTS

The distributions of minor allele in the XmnI locus, rs11886868, rs766432, and rs9399137 were 14%, 22%, 19% and 18% respectively. The variation allele in the XmnI locus, rs11886868, and rs766432 showed a significant value for modifying HbF and clinical score in HbE/β-thal patients, but rs9399137 did not demonstrate such features. In β-thal patients, however, no correlation was found for any single-nucleotide polymorphisms and clinical appearance.

CONCLUSION

The XmnI locus, rs11886868, and rs766432 have a modifying effect on HbF and clinical score in HbE/β-thal patients in Indonesia, but not in β-thal patients.

Blood transfusion from a Hb E trait donor can affect β-thalassemia diagnosis

A subject with Hb E (HBB: c.79G > A) trait is asymptomatic and can become a blood donor. However, a blood transfusion from a Hb E trait donor can affect β-thalassemia (β-thal) diagnosis. Blood samples from three Thai women were sent to the Associated Medical Sciences (AMS) Clinical Service Center, Chiang Mai, Thailand, for thalassemia diagnosis. Their Hb A2 levels, analyzed by high performance liquid chromatography (HPLC), were higher than 4.0%, thus they were diagnosed to have β-thal. However, elevated Hb A2 levels in these patients were not certain because the Hb A2 levels analyzed at the initial hospitalization and follow-up were controversial. In addition, there were some cases shown to have controversy between the increased Hb A2 level and red cell indices. The blood transfusion history was confirmed and hemoglobin (Hb) analysis was reanalyzed by capillary electrophoresis (CE). On the CE electrophoregram, Hb A2 levels were observed to be normal and Hb E peaks were present. Therefore, to rule out misdiagnosis and unnecessary genetic counseling, Hb analysis should be performed on the recipient prior to blood transfusions. Moreover, CE has a high efficiency to prevent the misinterpretation of Hb analysis in patients who receive blood transfusions from a donor carrying Hb E.

Five hemoglobin variants in a double heterozygote for α- and β-globin chain defects

Genetic interactions of different defective globin chains could render laboratory diagnostics in a routine setting difficult. We report a hitherto undescribed condition of double heterozygosity for hemoglobin (Hb) Q-Thailand with α(+)-thalassemia and Hb Tak found in 2 adult Thai individuals. Both patients were healthy and had no pertinent past medical history. A complete blood count revealed slight elevations of Hb and HCT values with low MCV and MCH. Interestingly, Hb analysis demonstrated, in addition to Hb A, A2, and F, as many as 5 Hb variants including Hb Tak (α(A)2β(Tak)2), Q-Thailand (α(QT)2β(A)2), QA2 (α(QT)2δ2), QF (α(QT)2γ2), and a novel variant, Hb QTak (α(QT)2β(Tak)2). Hematological findings of these unusual cases were compared with those of pure heterozygotes for Hb Q-Thailand and Hb Tak found in our series. Hb analysis using combined HPLC and capillary electrophoresis did help in the initial recognition and in making presumptive diagnoses, but definite diagnoses of these cases with complex α- and β-hemoglobinopathies could only be obtained after DNA analysis.

A proficiency testing program of hemoglobin analysis in prevention and control of severe hemoglobinopathies in Thailand

No external quality assessment program for hemoglobin (Hb) analysis in the prevention and control of thalassemia has been established in Thailand. To improve the first line provisional diagnostics, the first proficiency testing (PT) program has been established.

External Hb controls prepared at our center were sent to Hb analysis laboratories all over the country. Three cycles per year were performed in 2010 and 2011. In each cycle, two control samples with corresponding hematological parameters, designated as husband and his pregnant wife were supplied for Hb analysis. Each member analyzed the control samples in their routine practices. The results of Hb analysis, laboratory interpretation and risk assessment of the expected fetus for severe thalassemia diseases targeted for prevention and control were entered into the report form and sent back to our center. Participants reports were analyzed and classified into four different quality groups; Excellent (when all the three parameters are correct), Good (correct Hb analysis and interpretation but incorrect risk assessment), Fair (correct Hb analysis but incorrect interpretation and risk assessment) and Needs improvement (incorrect Hb analysis).

It was found that most participants could report correct Hb types and quantifications but some misinterpretations and risk assessments were noted. These were clearly seen when control samples with more complexity were supplied.

These results indicate a further improvement is required in the laboratory interpretation and knowledge of the laboratory diagnosis of thalassemia. The established system should facilitate the prevention and control program of thalassemia in the region.

Capillary zone electrophoresis for haemoglobinopathy diagnosis

Aims

Capillary zone electrophoresis (CE) at alkaline pH is increasingly used in haemoglobinopathy diagnosis. We report our evaluation of automated CE, using the Capillarys 2 Flex Piercing instrument, as a routine diagnostic method for the detection of variant haemoglobins and the diagnosis of β thalassaemia.

Methods

A Capillarys 2 Flex Piercing instrument with Phoresis software was evaluated in our laboratory over a 6-week period, comparisons being made with high performance liquid chromatography (HPLC) and, for haemoglobin A2 quantification, with microcolumn chromatography.

Results

The instrument was easy to use and was suitable for the quantification of haemoglobin A2. Quantification of A2 was precise and the percentage was stable with ageing of the blood specimen. Results differ among HPLC, CE and microcolumn chromatography and use of an instrument-specific, method-specific reference range is therefore recommended until such time as there is standardisation between methods and manufacturers. Common variant haemoglobins were provisionally identified without difficulty. There are some uncommon variant haemoglobins that are detected by HPLC but not by capillary electrophoresis, but the reverse also occurs.

Conclusions

Capillary electrophoresis using a Capillarys 2 Flex Piercing instrument is suitable for haemoglobinopathy diagnosis.

Expression of hemoglobin variant migration by capillary electrophoresis relative to hemoglobin A2 improves precision

We report the precision of the mean migration position of hemoglobin (Hb)S, HbC, HbG (Philadelphia), and HbD (Los Angeles) in 193 samples of whole blood assayed by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). By expressing the migration of Hb variants by CE relative to that of HbA(2) in the same sample, there was a significant improvement in the coefficient of variation for each variant studied. The potential usefulness of expressing Hb variants relative to that of HbA(2) was evaluated by comparing the separation of 2 closely migrating Hbs. When expressed by their initial migrations on CE, 25 of the 43 cases of HbG and HbD overlapped. However, when the migrations of these variants were expressed relative to the HbA(2) in the same sample, the 24 cases of HbG separated completely from the 19 cases of HbD. These findings suggest that expressing Hb variants relative to an internal standard, such as HbA(2), may be of value for establishing a library of variant Hbs evaluated by CE.

Comparison of capillary electrophoresis with cellulose acetate electrophoresis for the screening of hemoglobinopathies

BACKGROUND

β-thalassemia is primarily found in individuals of Mediterranean and Southeast Asian ancestry. With rapid growth in the Southeast Asian segments of the Korean population, the geographic distribution of hemoglobinopathies is expected to become significantly different from what it is today. In this study, Hb fractions were measured in patients with hypochromic microcytosis to detect thalassemia and Hb variants. To evaluate the feasibility of replacing cellulose acetate electrophoresis (CA) with capillary electrophoresis (CE) in a clinical laboratory, both techniques were performed and the outcomes were compared.

METHODS

To evaluate hemoglobinopathies, complete blood cell counts (CBC), CA, and CE were carried out on samples from healthy and microcytic hypochromic groups. The microcytic hypochromic group consisted of 103 patients whose mean corpuscular volume (MCV) was less than 75 fL and mean corpuscular hemoglobin (MCH) was less than 24 pg. Quantitative analysis of Hb fractions was performed on 143 whole blood samples.

RESULTS

There was a good correlation for measurements of HbA (r=0.9370, P<0.0001), HbA(2) (r=0.8973 P<0.0001), and HbF (r= 0.8010, P=0.0304) between the two methods. In the microcytic hypochromic group, there were 29 cases (28.2%) with decreased HbA(2), 2 cases (1.9%) with increased HbA(2), 3 cases (2.9%) with increased HbF, and 2 cases (1.9%) with increased HbA(2) and HbF.

CONCLUSIONS

CE is comparable to CA for reliable measurement of Hb fractions. It is suitable for screening of hemoglobinopathies in many clinical laboratories.

Interference of hemoglobin Hope on beta-thalassemia diagnosis by the capillary electrophoresis Method

The β-chain hemoglobin (Hb) variants interfere with the diagnosis of β-thalassemia trait using high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). We analyzed the effect of Hb Hope, a β-chain Hb variant frequently found in the Thai population, on β-thalassemia trait diagnosis. HPLC and CE were used to quantify the level of HbA(2) in 11 whole blood samples containing Hb Hope. The levels of Hb Hope detected by both methods were similar. An elevated HbA(2) level was found in all samples analyzed by the CE method, while 1 was increased when analyzed by HPLC, which was a compound heterozygous of Hb Hope and α-thalassemia-1 SEA-type deletion. Of 11 samples, 6 had mean corpuscular volumes within the reference range. All samples showed negative results for molecular analysis of β(0)-thalassemia codon 17, 41/42, and 71/72 mutations and β-thalassemia 3.5-kb deletion. Therefore, Hb Hope interfered with the diagnosis of β-thalassemia trait analyzed by CE but not by HPLC.