Hemoglobin A2 Lowered by Iron Deficiency and α -Thalassemia: Should Screening Recommendation for β -Thalassemia Change?

Assessment of diagnostic accuracy of Gazelle: A point-of-care testing device for screening β-thalassemia trait

Background & objectives Timely detection of population with β-thalassemia trait (BTT) followed by genetic counselling is an advocated method of preventing the birth of a child with β-thalassemia major. In this study we aim to assess the diagnostic accuracy of Gazelle, a point-of-care (POC) testing device, in screening for BTT in hospital laboratory setting. Methods Standards for Reporting Diagnostic Accuracy (STARD) guidelines were followed in developing study design, recruiting study participants and sample size calculation for the current research. A consecutive sample of 446 participants was recruited for this study and was tested for the reference test Gazelle as well as the gold standard cation exchange high performance liquid chromatography (CE-HPLC). Low serum ferritin levels are known to interfere with the production of HbA2 and in turn lead to false negative results. Hence, the study population was divided into two categories with respect to a cut off value of 15ng/dl of serum ferritin and the results were analyzed. Results Overall diagnostic accuracy of Gazelle for detecting BTT was found to be 95.3 per cent with a confidence interval (CI) of (92.9 - 97.1) and the sensitivity was 94.5 per cent with a 95% CI of (84.8 - 98.8). When analyzed by the serum ferritin level the diagnostic accuracy was found to be 94.7 per cent (91.1% - 97.1%) and 95.7 per cent (91.8% - 98.1%) for participants with serum ferritin level as > 15 ng/ml and < 15 ng/ml, respectively. Interpretation & conclusions This study found Gazelle to be a good screening tool for β-thalassemia trait with high sensitivity, specificity and accuracy. However, it is recommended that the final confirmation of the diagnosis done by a diagnostic test like HPLC or Capillary Zone Electrophoresis (CZE).

Algorithm of differential diagnosis of anemia involving laboratory medicine specialists to advance diagnostic excellence

OBJECTIVES

Anemia is a severe global public health issue. Testing practices for anemia suggest overuse of screening laboratory tests and misinterpretation of studies even in "easy-to-diagnose" underlying causes, leading to late diagnoses and missed treatment opportunities. We aimed to develop a complete and efficient algorithm for clinical pathologists and laboratory medicine physicians for the differential diagnosis of anemia.

METHODS

Comprehensive literature search encompassing original articles, studies, reviews, gold standard books, and other evidence.

RESULTS

We created a complex algorithm, primarily for clinical pathology/laboratory use, that explores all major and several rare causes of anemia in an efficient and evidence-based manner. The algorithm includes gold-standard diagnostic laboratory tests available in most clinical laboratories and indices that can be easily calculated to provide an evidence-based differential diagnosis of anemia.

CONCLUSIONS

The diagnostic strategy combines previously available diagnostic tests and protocols in an efficient order. Clinical pathologists following the algorithm can independently provide valuable diagnostic support for healthcare providers. Clinical pathologists providing complete differential diagnostic services with the proposed algorithm may create an opportunity for an advanced diagnostic service that supports diagnostic excellence and helps patients receive a timely diagnosis and early treatment opportunities.

Unresolved laboratory issues of the heterozygous state of β-thalassemia: a literature review

Although considered a mild clinical condition, many laboratory issues of the carrier state of β-thalassemia remain unresolved. Accurate laboratory screening of β-thalassemia traits is crucial for preventing the birth of a β-thalassemia major child. Identification of carriers in the laboratory is affected by factors that influence red cell indices and HbA2 quantification. Silent mutations and co-inheriting genetic and non-genetic factors affect red cell indices which decreases the effectiveness of the conventional approach. Similarly, the type of β mutation, co-inheriting genetic and non-genetic factors, and technical aspects, including the analytical method used and variations in the HbA2 cut-off values, affect the HbA2 results, leading to further confusion. However, the combination of mean corpuscular volume, mean corpuscular hemoglobin, and hemoglobin analysis increases the diagnostic accuracy. Diagnostic problems arising from non-genetic factors can be eliminated by carefully screening the patient's clinical history. However, issues due to certain genetic factors, such as Krüppel-like factor 1 gene mutations and α triplication still remain unresolved. Each laboratory should determine the population-specific reference ranges and be wary of machine-related variations of HbA2 levels, the prevalence of silent mutations in the community.

Work-up of Patients with Decreased Hemoglobin A2 Identified by Capillary Zone Electrophoresis: A North American Institutional Experience

OBJECTIVE

Isolated low hemoglobin A2 (HbA2) is rarely encountered in our clinical practice using capillary zone electrophoresis. The study goal was to characterize the work-up at our institution of patients with low HbA2.

METHODS

Patients with low HbA2 and a control cohort with normal capillary zone electrophoresis were identified and relevant information extracted from the medical record.

RESULTS

Of 44 patients with isolated decreased HbA2, 28 (64%) had corresponding complete blood count/ferritin values. Compared to control patients, patients with low HbA2 were more likely to have iron deficiency and demonstrated a more microcytic, hypochromic blood picture. However, 46% (13/28) of patients with low HbA2 and ferritin for evaluation did not have iron deficiency. Only 2 patients had genetic testing.

CONCLUSION

This study redemonstrates the association between low HbA2 and iron deficiency and reinforces the need for iron indices to interpret capillary zone electrophoresis results. Our study population showed incomplete or absent iron studies in most cases.

Iron interference in hemoglobin production in piglets from birth to weaning

ABSTRACT: Iron deficiency anemia (IDA) in humans is defined as the decrease of total hemoglobin concentration and the non-production of the adult hemoglobin subtype 2 - HbA2 (α2δ2 chains), which is considered a marker of IDA severity in humans, dosed together with the iron serum. This study aimed to determine the standard of hemoglobin types in piglets induced to experimentally IDA in the first 21 days of life (delivery to weaning). In the present study, 40 piglets born from four naïve gilts, were randomly and equally assigned among the gilts. On the third day after delivery, the groups were randomly distributed in different environments (cement and clay floors) and according to the iron supplementation (iron dextran and placebo). Erythrocyte parameters, serum iron, and hemoglobin trait were analyzed at four moments between birth and weaning days. The group of piglets that did not receive iron dextran supplementation on the third-day post-birth and were placed in the pen without soil did not present HbA2 from the seventh day onwards on the agarose electrophoretogram (pH 8.6) and this observation was correlated to decrease of serum iron (ρ: 0.156, p=0.003) when compared to the other groups’ piglets that did not present iron deficiency. In the present study was possible to determine the swine hemoglobin pattern in IDA, since HbA2 was absent in piglets with IDA in comparison to the non-ferropenic groups and the correlation between the reduction of iron levels and the absence of HbA2.

Spectrum of hemoglobinopathies with hematological and biochemical profile: A five year experience from a tertiary care hospital

BACKGROUND & OBJECTIVE

Determination of hemoglobinopathies is significant for epidemiological studies. There is a need to identify burden of hemoglobinopathies at national level to lay down the foundation of appropriate screening and prevention programs. The present study aimed to evaluate the spectrum of hemoglobinopathies along with hematological and biochemical parameters in a tertiary care hospital.

METHODS

This retrospective study included results of high performance liquid chromatography (HPLC) test from July 2015 - May 2020 in the department of Hematology, Indus Hospital and Health Network, Karachi, Pakistan. Data of all patients collected for red blood cell (RBC) indices, serum iron profile, and vitamin B12 and red cell folate levels. Diagnosis of hemoglobinopathies was done by an automatic analyzer ADAMS A1C Model No. HA-8180T Arkray/Japan.

RESULTS

Among 2422 participants, hemoglobinopathy observed in 14.5% (n=352). Beta thalassemia trait is observed as the most common hemoglobinopathy (6.4%). Severe anemia (Hb=5.1-5.5 g/dl) found in beta thalassemia major (BTM) and HbE disease. Red cell parameters showed significant association with different types of hemoglobinopathies. Mean ferritin level was high in E-beta thalassemia (687.8±591.9) followed by sickle cell disease (615.7±543.5).

CONCLUSION

Apparently, overall frequency is static however, results of this study are not applicable to general population due to sample bias. Moreover, true figures are difficult to identify due to high incidence of iron deficiency anemia that masks the diagnosis by conventional techniques. Molecular characterization by DNA analysis is the most reliable tool of diagnosis. However, this method is not widely available in our country due to lack of expertise and cost issues.

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.

Thalassemia and erythroid transcription factor KLF1 mutations associated with borderline hemoglobin A2 in the Thai population

INTRODUCTION

Elevated hemoglobin (Hb) A₂ is an important diagnostic marker for β-thalassemia carriers. However, diagnosis of cases with borderline Hb A₂ may be problematic. We described the molecular characteristics found in a large cohort of Thai subjects with borderline Hb A₂.

MATERIAL AND METHODS

Examination was done on 21,657 Thai subjects investigated for thalassemia at Khon Kaen University, Thailand. A total of 202 subjects with borderline Hb A₂ (3.5-4.0%) were selectively recruited and hematological parameters were recorded. DNA variants in α-, β-, δ-globin, and Krüppel-like factor 1 (KLF1) genes were examined using PCR.

RESULTS

Among 202 subjects, DNA analysis identified carriers of α⁺-thalassemia (n = 48; 23.8%), β-thalassemia (n = 22; 10.9%) and KLF1 mutations (n = 48; 23.8%). No molecular defect was observed in the remaining 84 (41.5%) subjects. Interaction of KLF1 and α-thalassemia was observed in 10 cases. Of the 22 β-thalassemia carriers, five β⁺-thalassemia mutations were identified with lower MCV and higher Hb A₂. Seven KLF1 mutations were detected in 10 genotypes in subjects with higher MCV and Hb F. No β⁰-thalassemia, α-globin gene triplication or δ-globin gene mutation was detected.

CONCLUSIONS

A large proportion of subjects with borderline Hb A₂ are not β-thalassemia carriers and for those with β-thalassemia, only mild β⁺-thalassemia mutations were detected. Evaluation of the patients using Hb A₂, Hb F and MCV values will help in selecting cases for further molecular analysis. The results should explain the unusual phenotype of the cases and facilitate a thalassemia screening program in the region.

Clinical utility of Abbott Alinity hq extended red blood cell parameters in differentiating β-thalassemia trait and iron deficiency anemia

INTRODUCTION

The objective of the study was to evaluate the performance of the Abbott Alinity hq advanced multi angle polarized scatter separation (MAPSS^TM )-based optical RBC technology, for the differentiation between iron deficiency anemia (IDA) and β-thalassemia carrier status.

METHODS

Four hundred and sixty-four samples were analyzed. 228 were healthy controls, 30 were β-thalassemia carriers, and 40 were IDA. Receiver operating characteristics analysis evaluated the performance of red cell parameters and mathematical formulas.

RESULTS

RBC concentration was the most efficient discriminant (area under the curve; AUC of 0.963, Youden Index of 0.88) followed by red blood cell distribution width in size distribution (AUC of 0.960 and YI of 0.86), and red blood cell distribution width coefficient of variation (AUC of 0.924, and YI of 0.74). The absolute reticulocyte concentration showed good diagnostic efficiency, with AUC of 0.808. Hemoglobin distribution width, the %CV of directly measured cellular hemoglobin concentration, and CHCr, the average hemoglobin concentration of reticulocytes have emerged as novel discriminating parameters, with AUC of 0.749 and 0.785, respectively. The England and Fraser index was the best discriminating mathematical formula based on Youden Index of 0.91. The Ricerca, red blood cell distribution width index, Green and King, and Mentzner Index formulas also showed strong discriminative power. The Shine and Lal index, together with the recent mathematical formula M/H, (ratio of percent microcytic and hypochromic red blood cells) demonstrated moderate performance with AUC of 0.796 and 0.740, respectively.

CONCLUSION

Extended red cell analysis delivered by the advanced optical technology on the Alinity hq hematology analyzer has efficient diagnostic utility in the initial discrimination of the two most common microcytic anemias: IDA and β-thalassemia trait.

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.

Regulatory Mutation Study in Cases with Unsolved Hypochromic Microcytic Anemia and α-Major Regulatory Element Haplotype Analysis in Iran

α-Thalassemia (α-thal) is an inherited blood disorder with different clinical manifestations. Although genetic causes of anemia are identified routinely in the majority of α-thal cases, a pathogenic variant in a few cases remains undiagnosed. In this study, some reported regulatory mutations have been investigated in five unsolved α-thal carriers. α-Major regulatory element (α-MRE) haplotype analysis has also been performed in Iran for the first time. Four regions, including the HBA2 core promoter, the highly conserved sequence of hypersensitive-40 (HS-40), a region containing regulatory single nucleotide polymorphism (SNP) CR062116, and a region containing rs7203560, were screened for changes by Sanger sequencing in a total of five unsolved suspected α-thal carriers. The frequencies of α-MRE haplotypes B and C were also determined in control samples with normal hematological indices. No pathogenic variant was found in the investigated regions. Haplotype frequencies observed for B and C haplotypes fell into the range of frequencies observed in previous studies. The investigated genotypes in the control group were in the Hardy-Weinberg equilibrium. This study can provide evidence that there is no association between the B haplotype and microcytic hypochromic anemia. The cause of anemia remains a mystery in our unsolved cases, which demonstrates the need for further studies on the causes of hypochromic microcytic anemia in individuals with intact α- and β-globin genes without iron deficiency.

Molecular Characterization of β- and α-Globin Gene Mutations in Individuals with Borderline Hb A2 Levels

Elevated Hb A₂ level (≥4.0%) is considered to be reliable parameter to identify β-thalassemia (β-thal) carriers. However, some β-thal carriers have been misdiagnosed as their Hb A₂ levels are below 4.0%. In addition, coinheritance of α-thalassemia (α-thal) and β-thal might affect Hb A₂ levels. Therefore, the aim of this study was to investigate the mutations of β- and α-globin genes in individuals with borderline Hb A₂ levels in Thailand. Three hundred samples from individuals with Hb A₂ levels of 3.5-3.9% were collected for molecular diagnosis of β-globin gene mutations. In addition, the α⁰-thal, α⁺-thal, Hb Constant Spring (Hb CS, HBA2: c.427T>C), and Hb Paksé (HBA2: c.429A>T) diagnostics were also performed. Sixteen samples (5.33%) had β-globin gene mutations, and codon 41/42 (-TTCT) (HBB: c.126_129delCTTT) was the most prevalent mutation. Ninety-eight samples (32.67%) had α-globin gene mutations including four Hb H (β4)-Hb CS disease, two Hb H disease, 13 heterozygous α⁰-thal, 11 homozygous α⁺-thal, two α⁺-thal/Hb CS, one α⁺-thal/Hb Paksé, 61 heterozygous α⁺-thal, and four Hb CS. Furthermore, seven cases of β-thal carriers coinheriting α-thal were observed, and five of them carried Hb H disease. High prevalence of both α- and β-thal in subjects with borderline Hb A₂ levels suggested that molecular diagnosis of α- and β-thal should be performed, especially in a high prevalence area of thalasssemia carriers, for accurate diagnosis and genetic counseling to prevent and control new severe thalassemia cases. Moreover, β-thal carriers who coinherited Hb H disease might have reduced Hb A₂ levels, leading to a misdiagnosis of β-thal in analysis programs.

The Spectrum of α-Thalassemia Mutations in Kurdistan Province, West Iran

In order to identify the α-thalassemia (α-thal) mutation spectrum in Kurdistan Province, West Iran, a total of 217 individuals, including 154 α-thal carriers and 63 normal subjects were investigated in this study. Molecular analysis of α1- and α2-globin genes using multiplex gap-polymerase chain reaction (gap-PCR), amplification refractory mutation system (ARMS)-PCR or direct DNA sequencing, showed 11 different α-globin variants. The -α^3.7 (rightward) deletion (NG_000006.1: g.34164_37967del3804) (70.32%), polyadenylation signal (polyA2) site (AATAAA>AATGAA) (α^polyA2α) (HBA2: c.*92A>G) (7.74%), -α^4.2 (leftward) deletion (6.45%) and codon 59 (or Hb Adana) (G>A) (αα^{codon 59}) (HBA1: c.179G>A) (4.52%) were the most frequent mutations in the present study. In conclusion, the spectrum of α-thal mutations in Kurdistan Province is closest to that in western provinces of Iran (Kurdish and Laki populations). In addition, it was revealed that the codon 59 mutation is common in the Kurdish population. On the other hand, despite the same ethnic background of Kurds in Iran and Iraq, the - -^{MED I} double gene deletion and polyA2 point mutation have different distributions in these two populations. Therefore, further studies are needed to identify the cause of these differences.

α-Thalassemia Mutations in Ilam Province, West Iran

Despite several studies performed in different provinces of Iran to identify the spectrum of α-globin gene mutations, no such study has so far been carried out in Ilam Province. A total of 274 individuals, including 201 α-thalassemia (α-thal) carriers and 73 normal subjects, originating from the northern counties of Ilam Province, participated in this study. Analysis of α-globin defects was performed using multiplex gap-polymerase chain reaction (gap-PCR), amplification refractory mutation system (ARMS)-PCR and direct sequencing, which revealed a total of 11 different mutations and 22 different genotypes. The -α^3.7 (rightward) (NG_000006.1: g.34164_37967del3804), α^-5 ntα (HBA2: c.95 + 2_95 + 6delTGAGG), and -α^4.2 (leftward) deletions were the most prevalent mutations identified in our study, with frequencies of 66.23, 10.09 and 8.33%, respectively. In conclusion, the present study showed that the α-thal mutation spectrum in Ilam Province, at least in the northern part of the province, is different from that in other geographical regions of Iran. These results increase our knowledge about the spectrum and distribution of α-globin gene mutations in Iran.

Nationwide carrier detection and molecular characterization of β-thalassemia and hemoglobin E variants in Bangladeshi population

BACKGROUND

ß-thalassemia is one of the most common inherited blood disorders in the world and a major deterrent to the public health of Bangladesh. The management of thalassemia patients requires lifelong frequent blood transfusion and the available treatment options are unsatisfactory. A national policy on thalassemia prevention is mandatory in Bangladesh. However, precise and up-to-date information on the frequency of ß-thalassemia carriers are missing due to lack of accurate diagnostic approaches, limited access to information and absence of national screening program. This study aims to determine the nationwide carrier frequency of hemoglobin E (HbE) and β- thalassemia and mutation spectrum among the carriers using molecular, hematological and biochemical methods.

METHODS

The study enrolled a total of 1877 individuals (60.1% male and 39.9% female) aged between 18 and 35 years. Total sample size and its division-wise breakdown were calculated in proportion to national and division-wise population. Venous blood was collected and subjected to CBC analysis and Hb-electrophoresis for each participant. Serum ferritin was measured to detect coexistence of iron deficiency anemia with thalassemia carrier. DNA-based High Resolution Melting (HRM) curve analysis was performed for confirmation of carrier status by mutation detection.

RESULTS

Of 11.89% (95% CI, 10.43-13.35) carriers of β-globin gene mutations, 8.68% (95% CI, 7.41-9.95) had HbE trait (ETT) and 2.24% (95% CI, 1.57-2.91) had beta-thalassemia trait (BTT). Among eight divisions, Rangpur had the highest carrier frequency of 27.1% (ETT-25%, BTT-2.1%), whereas Khulna had the lowest frequency of 4.2% (ETT-4.2% only). Moreover, α- thalassemia, HbD trait, HbE disease, hereditary persistence of HbF were detected in 0.11, 0.16, 0.43 and 0.16% participants, respectively. HRM could identify two individuals with reported pathogenic mutations in both alleles who were erroneously interpreted as carriers by hematological indices. Finally, a total of nine different mutations including a novel mutation (c.151A > G) were detected in the β-globin gene.

CONCLUSIONS

Since carrier frequency for both HbE and β-thalassemia is alarmingly high in Bangladesh, a nationwide awareness and prevention program should be made mandatory to halt the current deteriorating situations. Mutation-based confirmation is highly recommended for the inconclusive cases with conventional carrier screening methods to avoid any faulty detection of thalassemia carriers.

Consensus Statement by an Expert Panel on the Diagnosis and Management of Iron Deficiency Anemia in the Gulf Cooperation Council Countries

BACKGROUND

Iron deficiency (ID) and ID anemia (IDA) are common in the member states of the Gulf Cooperation Council (GCC). The unique genetic and lifestyle factors of the patient population in the region have necessitated the development of recommendations to help educate health-care professionals on appropriate diagnosis and management of ID/IDA.

METHODS

A panel of regional experts, including gastroenterologists and hematologists with expertise in the treatment of IDA, was convened to develop regional practice recommendations for ID/IDA. After reviewing the regional and international literature, the expert panel developed consensus recommendations for screening, diagnosis, and treatment of patients with IDA in the GCC region.

RESULTS

The recommendations proposed were customized to the patient population keeping in view the increasingly recognized burden of coeliac disease, high fertility and obesity rates, high prevalence of alpha- and beta-thalassemia traits, and poor tolerance and low treatment compliance with oral iron therapy.

CONCLUSIONS

This consensus statement proposes recommendations for screening, diagnosis, and treatment of IDA in the GCC region.

Optimization and application of a dried blood spot-based genetic screening method for thalassemia in Shenzhen newborns

BACKGROUND

To optimize and apply an approach suitable for large-scale neonatal thalassemia genetic screening in China, thalassemia genotypes were determined by polymerase chain reaction-reverse dot blot using DNA extracted from dried blood spots (DBS) obtained from newborn screening programs.

METHODS

Firstly, the most suitable commercial DNA extraction kit for DBS was screened. Then, the appropriate amount of DBS required for the automated high-throughput DNA extraction system was evaluated. Finally, the thalassemia prevalence and genotype spectrum in Shenzhen were investigated in 2028 newborns using the optimized screening procedure.

RESULTS

The Magentec extraction kit was best suited for the automated DBS DNA extraction system using eight 3-mm DBS discs. The neonatal thalassemia prevalence in Shenzhen was 9.12%; 6.31% α-thalassemia, 2.37% β-thalassemia, and 0.44% α-/β-thalassemia.

CONCLUSIONS

Genetic screening based on DBS can precisely identify the thalassemia genotypes. Both α- and β-thalassemia are widely distributed in Shenzhen newborns. Newborn genetic screening is important for establishing a comprehensive thalassemia prevention program and for public education.

Hemoglobin A2 (HbA2) has a measure of unreliability in diagnosing β-thalassemia trait (β-TT)

INTRODUCTION

Detection of β-thalassemia trait or carriers (β-TT) depends significantly on an increase in Hemoglobin A₂ (HbA₂) levels, which is found at low levels (<3%) in normal healthy individuals and elevated levels (≥3.5%) in β-TT individuals. The study was designed to evaluate the reliability of the diagnostic parameter HbA₂ in the differentiation of β-TT and non-β-TT in Saudis.

METHODS

The widely used high performance liquid chromatography (Variant II Bio-Rad) was used to measure HbA₂ levels in blood. Sanger sequencing was used to screen the variation in globin genes (HBB, HBD, HBA1, and HBA2). All the study subjects were divided into βTT and non-βTT (wild) categories based on the presence or absence of HBB variations and further sub-divided into false positive, true positive, false negative, and true negative, based on HbA₂ values.

RESULTS

Out of 288 samples, 96 had HBB gene mutations. Of the 96 β-TT samples, sickle cell trait (SCT) samples (n = 58) were excluded, while the remaining (38 β-TT) were included in the detailed analysis: seven subjects with the HBB mutation had normal HbA₂ (<3%), and three were borderline (3.1-3.9%). The remainder (n = 28) had an elevated HbA₂ level (>4%). Based on HbA₂ analysis alone, both these groups would be incorrectly diagnosed as normal. Similarly, of the 189 non-β-TT samples, 179 had normal HbA₂, eight had borderline HbA₂, and two had a HbA₂ level above 4%. Based on HbA₂ analysis alone, borderline and >4% HbA₂ individuals, negative for β-TT, can be incorrectly diagnosed as carriers.

CONCLUSION

Given the percentage of samples falling in the HbA₂ "borderline" and "normal" categories, it can be concluded that HbA₂ has a measure of unreliability in the diagnosis of β-thalassemia carriers.

Higher minor hemoglobin A2 levels in multiple sclerosis patients correlate with lesser disease severity

OBJECTIVE

To define whether minor adult hemoglobin A2 (HbA2, α2δ2) exerts any protective activity in multiple sclerosis (MS).

METHODS

HbA2 levels were measured in 146 MS patients with high performance liquid chromatography and association with MS Severity Scores (MSSS) were determined. HbA2 associations with blood count parameters were also studied using blood counts evaluated on the same day of high performance liquid chromatography sampling. Routine biochemical parameters were also determined to rule out elusively influential factors, such as anemia and thyroid disorders.

RESULTS

HbA2 levels negatively correlated with MSSS (Spearman correlation, R: -0.186, P=0.025). Exclusion of confounding factors with a generalized linear model revealed an even stronger negative correlation between HbA2 and MSSS (P<0.001). HbA2 positively correlated with red blood cells (RBCs) (R=0.350, P<0.001) and in turn, RBCs negatively correlated with MSSS (R=-0.180, P=0.031). Average HbA2 levels were highest among patients treated with interferon β1a.

CONCLUSION

RBC fragility is increased in MS, and recent data suggest that circulating free Hb contributes to neural injury in MS. HbA2 and its oxidative denaturation product hemichrome A2 enhance RBC membrane stability to a greater extent than do major HbA or hemichrome A. Reductions in ischemic cerebrovascular vascular events are reported in β-thalassemia carriers and HbA2 levels are considerably higher in this population. Episodic declines of cerebral blood flow were shown in bipolar disorder, and we have recently shown a protective role of HbA2 against postpartum episodes in females with bipolar disorder. HbA2's erythroprotective functions may reduce free Hb and long-term neural injury in MS.

Haemoglobinopathies that occur with decreased HbA2 levels: a gene mutation set involving the δ gene at a Spanish centre

AIMS

Haemoglobin A₂ (HbA₂) consists of two globin chains, α and β. Alterations in any of these genes influences the level of HbA₂. Here, we present cases of structural Hb variants and thalassaemias which present either alone or together and reduce the level of HbA₂ at varying degrees. Furthermore, we present a novel structural mutation in the δ globin gene, called Hb A₂-Madrid.

METHODS

The levels of HbA₂ and HbF and the different haemoglobin variants were measured and analysed by ion exchange high performance liquid chromatography (HPLC, VARIANT II), the types of haemoglobins were determined by capillary zone electrophoresis (CZE) (Sebia) and the globin chains were determined by reversed-phase HPLC. Genetic analysis was performed by automatic sequencing of the α and δ genes as well as by multiple PCRs for the α globin genes.

RESULTS

In α thalassaemia (n=94), the HbA₂ levels ranged from 1.39% to 2.43%. Among individuals with δ thalassaemia (n=5), the HbA₂ level of those with δ⁺ thalassaemia was 1.77%, and that of those with δ⁰ thalassaemia was 1.70%. Among the individuals with δβ thalassaemia (n=13), those who were homozygous lacked HbA₂. All structural haemoglobinopathies (n=97) were heterozygous; the α chain variants (n=84) presented with an HbA₂ level of 1.76%, while the δ chain variants (n=13) presented with a level of 1.75%.

CONCLUSION

HbA₂ is an essential parameter in the diagnostics of haemoglobinopathies. HPLC-EC and CZE allow the quantification of HbA₂. Here, we show that quantification of HbA₂ is critical for the identification of α, δ and βδ thalassaemias. Structural variants are discovered by HPLC. Molecular genetics is required for the proper identification of the mutations. Only with this knowledge is genetic counselling possible.

A Large Cohort Study of Genotype and Phenotype Correlations of Beta- Thalassemia in Iranian Population

BACKGROUND

Thalassemia syndromes are the most prevalent single gene disorders in Iran. This study aimed to evaluate the effect of different types of beta-globin gene mutations, co-inheritance of alpha-globin gene mutations and/or Xmn1 SNP on disease phenotype in a large cohort of Iranian patients.

SUBJECTS AND METHODS

In total, 433 patients were clinically classified into β-thalassemia major (TM) or intermedia (TI). Multiplex PCR, ARMS-PCR, RFLP-PCR and DNA sequencing were performed to identify both α- and β-globin gene mutations and Xmn1 polymorphism as well. All data were compared and analyzed by SPSS software in TM and TI groups, consequently.

RESULTS

A total of 39 different β-globin mutations were identified. Among them, the most common were IVS IInt1 (40.33%) followed by IVS Int5 (9.56%), C30 (7.22%) and Fr8-9(7%). All patients were subjected to evaluate common α-globin gene deletions. The patients inherited concomitant mutations of α- and β-globin, showed no clinical modifications compared with those who had only β-globin mutation. The TI patients showed a significant increase in frequency of both heterozygous and homozygous form of the Xmn1 polymorphism. It was also found that β(0)/β(0) genotype patients, inherited the Xmn1 polymorphism required lesser blood transfusion.

CONCLUSION

No significant differences were observed, on the severity of disease, between patient's inherited defective α- and β-globin genes and ones with just β-globin gene mutation. Taking the results of this research into account, Xmn1 polymorphism can be considered as an important genetic factor modulating the severity of disease.

Impact of iron deficiency on hemoglobin A2% in obligate β-thalassemia heterozygotes

INTRODUCTION

The potential impact of concomitant iron deficiency on hemoglobin A2 (HbA2)-based identification of β-thalassemia trait (βTT) is a worrisome issue for screening laboratories. This is especially true for resource-constrained settings where iron deficiency is widespread and molecular confirmatory tests for borderline low HbA2 values may be unavailable.

METHODS

Obligate βTT carrier individuals (n = 752) were identified during screening studies on the parents of thalassemia major patients. HbA2%, complete blood counts and serum iron, ferritin and transferrin saturation were studied. Iron-deficient individuals (n = 135) with normal range HbA2% were taken as controls.

RESULTS

Concomitant iron deficiency (defined as ferritin ≤15 ng/mL and/or transferrin saturation ≤15%) was present in 20.7% (156/752) βTT cases, that is, 33.3% females (122/366) and 8.8% males with βTT (34/386). Mean HbA2 in iron-replete βTT was 5.4 ± 0.8 (range 3.1-7.9) and in iron-deficient βTT was 5.4 ± 0.9 (range 3.3-7.6). HbA2 < 4.0% was found in 23/752 (3.1%) βTT: 13/595 iron-replete (2.2%) and 10/157 (6.4%) iron-deficient βTT individuals. However, five of the 10 iron-deficient βTT cases carried the silent CAP+1 (A>C) β-thalassemia allele accounting for the borderline HbA2%. On a separate analysis, all five severely anemic βTT (Hb < 80 g/L) and 16/17 βTT with severe hypoferritinemia (<5 ng/mL) had HbA2 > 4.5%. The single case with serum ferritin 4.8 ng/mL and HbA2 3.3% showed a CAP+1 (A>C) mutation.

CONCLUSIONS

Iron deficiency was prevalent among north Indian βTT individuals, especially women. After adjusting for other causes of low HbA2 in βTT, iron deficiency, even when very severe, was very unlikely to interfere significantly with HbA2-based identification of βTT.

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.

Haemoglobinopathies in eastern Indian states: a demographic evaluation

Haemoglobinopathies are a leading cause of child mortality worldwide, although with a variable geographical incidence. A reliable estimate of prevalence of the disease is necessary for reducing its burden. However, most studies in India are either hospital based or from certain regions of the country and hence may not realistically reflect the disease burden. The eastern Indian states of Bihar, Chhattisgarh and Jharkhand and eastern region of Uttar Pradesh, which comprise ~25 % population of the country, are poorly studied with respect to haemoglobinopathies. The present study, conducted on 1,642 individuals from this region, shows a frequency of 3.4 % for β-thalassaemia trait (BTT), 3.4 % for sickle cell haemoglobin trait (HbS)/haemoglobin E trait (HbE) and 18 % for α-globin defects. While BTT mutations are distributed rather uniformly across the region, HbS occurs only in Chhattisgarh and Jharkhand, the regions rich in tribal populations. The frequency of α-gene mutation is strikingly high, occurring even in individuals with normal blood count, in tribal as well as non-tribal groups. The mutation spectrum of BTT is also distinct since the common mutations, IVS1-1 (G-T) and 619 bp del, are absent while CD15 (G-A) is the second most frequent. The HbA2 level in the suspected cases is strikingly low. We demonstrate association of the low HbA2 level with vitamin B12 and folate deficiency in this cohort. Thus, the present report besides providing an estimate of the carrier frequency of β-thalassaemia traits also confirms high prevalence of α-gene defects and regional heterogeneity in distribution of HbS in the eastern parts of India.

Half of the Emirati population has abnormal red cell parameters: challenges for standards and screening guidelines

In populations with high prevalences of iron deficiency and thalassemia trait, many apparently healthy individuals have abnormal erythroid parameters, which may cause diagnostic problems in clinical practice. We studied the prevalence and causes of red cell parameter values outside their reference ranges in 394 healthy individuals of Bedouin Arab origin, who had complete blood counts (CBCs), hemoglobin (Hb) analyses and serum ferritin tests done. Their mean age ± standard deviation (SD) was 24.8 ± 4.9 years and 51.8% were females. Overall, 53.0% (209/394) had low Hb, MCV or MCH or high RDW. Anemia was present in 27.0% (55/204) of the women and 3.0% (6/190) of the men. Overall prevalence of MCV < 80.0 fL was 45.0% (176/394) and MCH < 27.0 pg was 48.0% (190/394); RDW > 14.0% was found in 21.0% (43/204) of women and 7.0% (14/190) of men. Of the women, 16.0% had iron deficiency anemia (33/204) and 65.0% had ferritin values of < 30.0 μg/L (133/204). The estimated prevalence of α-thalassemia (α-thal) trait in men was 32.0% (60/190) and that of β-thalassemia (β-thal) trait in both sexes was 3.0% (12/394). In conclusion, half of the healthy Emirati population have abnormal CBC values. For clinical purposes, they require reference standards for red cells that are derived from their own population. Screening of women for iron deficiency is justified due to a high prevalence of iron deficiency.