Differentiation between Thalassemia Trait and Iron Deficiency Anemia Based on Low Hemoglobin Density and Microcytic Anemia Factor.

BACKGROUND: The most common causes of microcytic hypochromic anemia are thalassemia trait (TT) and iron deficiency anemia (IDA). Clinically, the differential diagnosis of TT and IDA is crucial, but it is typically challenging. Thus, in order to differentiate between TT and IDA, we seek to develop a new discriminative index on an automatic hematology analyzer utilizing the two new RBC characteristics of low hemoglobin density (LHD) and microcytic anemia factor (MAF). METHODS: We recruited a total of 323 subjects, including 115 healthy controls, 83 TT, and 125 IDA. An automated hematology analyzer (DxH800, Beckman Coulter) was used to determine peripheral blood parameters; LHD and MAF were calculated using the parameters of MCHC, Hb, and MCV. The receiver operating characteristic (ROC) curve was used to determine the cutoff values and evaluate the diagnostic value for TT and IDA. RESULTS: LHD was significantly lower in TT than IDA, whereas MAF was higher. To distinguish between TT and IDA, a new formula based on LHD and MAF was developed, with a cutoff value of 0.5, AUC of 0.9706 (95% CI: 0.9503 - 0.9909), and specificity, sensitivity, positive predictive value, and negative predictive values were 92.91%, 91.36%, 89.16%, and 94.40%, respectively. The new formula has proven advantages over conventional indices, such as RDW-SD, MCV, MCH, etc. Conclusions: The RBC parameters LHD and MAF detected by hematology analyzer could be useful for screening for TT and IDA. Our new formula outperforms other discriminant formulas in the literature with high sensitivity and specificity, is simple, rapid, and can aid in early detection and management.

Two Novel α-Thalassemia Mutations CD 39 -C [Thr > Pro] and CD 109 ACC > CCC [Thr > Pro] Identified in Two Chinese Families: A Case Report.

We reported the identification of two rare α-thalassemia silent carriers with novel HBA1 mutations of CD 39 -C [Thr > Pro] (HBA1: c.114del; p.Thr39Profs*11) and CD 109 ACC > CCC [Thr > Pro] (HBA1: c.325A > C; p. Thr109Pro), respectively. The two probands were pregnant women diagnosed with mild hypochromic anemia or microcytic hypochromic anemia by routine blood tests. They started iron therapy before taking differential diagnosis from iron deficiency anemia. After wait and watch approach, they both accepted thalassemia genetic screening, which identified CD 39 -C [Thr > Pro] and CD 109 ACC > CCC [Thr > Pro], respectively. Due to inappropriate iron therapy, worse anemia and iron overload were noticed in the first proband, but no obvious side effect was found in both probands. Functional analysis showed that, relative to the wild type, CD 39 -C [Thr > Pro] considerably reduced the expression of the HBA1 protein while CD 109 ACC > CCC [Thr > Pro] only had a minor impact. Our study highlighted the importance of gestational thalassemia screening based on next-generation sequencing for identifying novel rare thalassemia variants and increased our understanding about the relationship between genotype and phenotype of α-thalassemia.

Heterozygosity for the Novel HBA2: c.*91_*92delTA Polyadenylation Site Variant on the α2-Globin Gene Expanding the Genetic Spectrum of α-Thalassemia in Iran.

There are four copy numbers of α-globin genes (16p13.3) in the human genome and the number of defective α-globin genes dictates the severity of α-thalassemia (α-thal). Mutations that occur in the 3' untranslated region (3'UTR), and especially at the polyadenylation (polyA) sites, affect the translation, stability and export of mRNA. A patient with hypochromic microcytic anemia was referred to the Kariminejad-Najmabadi Pathology & Genetics Center, Tehran, Iran by the health network. Molecular analysis of genomic DNA for the evaluation of mutations on the α- and ß-globin genes was performed. Direct sequencing of the hemoglobin (Hb) subunit α2 (HBA2) gene revealed a two nucleotide deletion between +816 and +817 in the 3'UTR, located at the polyA site, which seems to be a novel pathogenic variant. This novel variant expands the genetic spectrum of α-thal in the 3'UTR of the HBA2 gene.

Nondeletional α-Thalassemia: Two New Mutations on the α2 Gene.

About 10.0% of α-thalassemia (α-thal) cases are due to point mutations, small deletions, or insertions of one or more bases on the α genes that can alter mRNA processing at the transcription, translation, or post-translation level; these cases are called nondeletional α-thalassemias (α-thal). Most occur within the domain of the α2 gene without changes in the expression of the α1 gene. We present two new frameshift mutations on the HBA2 gene, associated with a nondeletional α-thal phenotype. The probands were referred to our clinic because of persistent microcytosis and hypochromia. The molecular characterization was performed by automatic sequencing of the α-globin genes. Two new mutations were detected on the HBA2 gene; HBA2: c.85delG, p.(Ala29fs*21), and HBA2: c.268_280delCACAAGCTTCGGG, p.(His90Trpfs*9). These new mutations cause a change of the reading frame, the first on codon 28 and the second from codons 89 to 93. In the first mutation, the result is an altered amino acid sequence and a premature termination codon at position 87, while the elimination of 13 bp generates a protein of 95 residues and in this case, the premature termination codon is at position 96. These types of mutation are among the most damaging changes to the coding of a protein. Not only do they lead to changes in the length of the polypeptide, but they also vary the chemical composition, which would result in a nonfunctional protein. The importance of identifying these new mutations lies in their possible association with α0-thal, which could lead to a severe thalassemia.

An Unusual Compound Heterozygosity for Hb O-Arab (HBB: c.364G>A) and Hb D-Los Angeles (HBB: c.364G>C).

We report a newborn with a compound heterozygosity for Hb O-Arab (HBB: 364G>A) and Hb D-Los Angeles (HBB: 364G>C). To the best of our knowledge, the combination of these two hemoglobin (Hb) variants has not been identified and reported before. The variants of the proband and parents were identified by high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). DNA analysis was performed to confirm the variants. The levels of Hb variants of the proband were determined post-partum, at 3 months and 1 year after birth. Blood count analysis after 1 year revealed that the proband had a mild microcytic anemia. Furthermore, HPLC and CE analysis revealed an equal distribution of Hb D-Los Angeles compared to Hb O-Arab at the age of 1 year. The follow-up of the patient, suggested that the Hb combination is clinically silent or mild.

A Novel ß-Thalassemia Mutation [IVS-I-6 (T>G), HBB: c.92+6T>G] in a Chinese Family.

ß-Thalassemia (ß-thal) is one of the most common inherited hemoglobin (Hb) disorders in southern China. Up to now, the mutation spectrum of ß-thal has been increasingly broadened through various molecular methods. In this study, a 34-year-old female displaying microcytic, hypochromic anemia was first detected with a novel IVS-I-6 (T>G) (HBB: c.92+6T>G) mutation by Sanger sequencing. Pedigree analysis performed on her family showed that her mother and her daughter, who had abnormal hematological indices, also carried this mutation, while her other family members with normal hematological phenotypes, were not detected to carry any mutation. Based on the observed symptoms in this Chinese family, we concluded that this novel mutation was associated with a mild ß-thal phenotype.

α-Globin Genotypes Associated with Hb H Disease: A Report from Oman and a Review of the Literature from the Eastern Mediterranean Region.

α-Thalassemia (α-thal) is the most common autosomal recessive hemoglobinopathy. There is a vast diversity and geographical variability in underlying genotypes in Hb H (ß4) patients. Herein, we describe the genotypes found in the largest report of Omani Hb H patients. Moreover, we reviewed and summarized the literature published from the Eastern Mediterranean region. A retrospective review of all genetically confirmed Hb H disease patients diagnosed between 2007 and 2017 at Sultan Qaboos University Hospital, Muscat, Oman, was performed. Hematological parameters and clinical presentations were assessed. Both α-globin genes were screened for deletional and nondeletional mutations using a stepwise diagnostic strategy as described before. A total of 52 patients (27 females and 25 males) with a mean age of 20.6 years (range 0.23-80.0) were molecularly confirmed to carry Hb H disease. The patients had a hemoglobin (Hb) level of 9.3 g/dL (range 5.7-13.0) and mean corpuscular volume (MCV) of 58.4 fL (range 48.2-82.1). A total of eight genotype combinations were identified, with α2 polyadenylation signal mutation (polyA1) (AATAAA>AATAAG (αPA1α/αPA1α), often cited as αT-Saudiα/αT-Saudiα, being the most common (53.8%) followed by -α3.7/- -MED I (28.8%). Our cohort also included patients with combinations of αPA1 with other Hb variants: αPA1α/αPA1α with Hb S (HBB: c.20A>T) trait (n = 2), -α3.7/αPA1α (n = 2) and αcodon 19α (HBA2: c.56delG)/αPA1α (n = 1). Nondeletional Hb H disease due to the αPA1 mutation is the most common in Omanis. Molecular diagnosis is necessary for accurate confirmation of the diagnosis of α-thal, determination of underlying genotypes, follow-up and counseling.

Association between Different Polymorphic Markers and ß-Thalassemia Intermedia in Central Iran.

ß-Thalassemia intermedia (ß-TI) is a clinical condition characterized by moderate, non transfusional anemia and hepatosplenomegaly. The main objective of this study was to determine the molecular basis of the clinical phenotype of ß-TI in Iran. To elucidate the mild phenotype of many patients with ß-TI, we screened for three prevalent ß-globin gene mutations [IVS-II-1 (G>A) HBB: c.315+1G>A, IVS-I-110 (G>A) HBB: c.93-21G>A and IVS-I-5 (G>C) [HBB: c.92+5G>C], deletions on the α-globin genes, XmnI polymorphisms and restriction fragment length polymorphism (RFLP) haplotypes on the ß-globin gene cluster in 50 ß-TI patients. Fifty-eight percent of the patients (29 cases) were associated with the mentioned mutations. We showed that the HBB: c.315+1G>A mutation is linked to haplotype [+ - + +] (57.69%). This haplotype is in linkage disequilibrium with the XmnI polymorphism (NG_000007.3: g.42677C>T) and has been associated with increased expression of Hb F in ß-TI patients. The XmnI polymorphism is defined in association with this prevalent mutation. Two patients had a single α-globin gene deletion [-α3.7 (rightward) deletion]. The main genetic factor in mild phenotype ß-TI patients is the linkage of an XmnI polymorphism (NG_000007.3: g.42677C>T) with the HBB: c.315+1G>A (80.76%), which is associated with increased production of Hb F and coinheritance of haplotype [+ - + +] with ß-TI, especially with the homozygous HBB: c.315+1G>A mutation. Molecular basis of ß-TI could be explained by the involvement of different factors that tend to develop the disease phenotype.

ThalPred: a web-based prediction tool for discriminating thalassemia trait and iron deficiency anemia.

BACKGROUND: The hypochromic microcytic anemia (HMA) commonly found in Thailand are iron deficiency anemia (IDA) and thalassemia trait (TT). Accurate discrimination between IDA and TT is an important issue and better methods are urgently needed. Although considerable RBC formulas and indices with various optimal cut-off values have been developed, distinguishing between IDA and TT is still a challenging problem due to the diversity of various anemic populations. To address this problem, it is desirable to develop an improved and automated prediction model for discriminating IDA from TT. METHODS: We retrospectively collected laboratory data of HMA found in Thai adults. Five machine learnings, including k-nearest neighbor (k-NN), decision tree, random forest (RF), artificial neural network (ANN) and support vector machine (SVM), were applied to construct a discriminant model. Performance was assessed and compared with thirteen existing discriminant formulas and indices. RESULTS: The data of 186 patients (146 patients with TT and 40 with IDA) were enrolled. The interpretable rules derived from the RF model were proposed to demonstrate the combination of RBC indices for discriminating IDA from TT. A web-based tool 'ThalPred' was implemented using an SVM model based on seven RBC parameters. ThalPred achieved prediction results with an external accuracy, MCC and AUC of 95.59, 0.87 and 0.98, respectively. CONCLUSION: ThalPred and an interpretable rule were provided for distinguishing IDA from TT. For the convenience of health care team experimental scientists, a web-based tool has been established at http://codes.bio/thalpred/ by which users can easily get their desired screening test result without the need to go through the underlying mathematical and computational details.

Critical appraisal of discriminant formulas for distinguishing thalassemia from iron deficiency in patients with microcytic anemia.

BACKGROUND: Many discriminant formulas have been reported for distinguishing thalassemia trait from iron deficiency in patients with microcytic anemia. Independent verification of several discriminant formulas is deficient or even lacking. Therefore, we have retrospectively investigated discriminant formulas in a large, well-characterized patient population. METHODS: The investigational population consisted of 2664 patients with microcytic anemia: 1259 had iron deficiency, 1196 'pure' thalassemia trait (877 ß- and 319 α-thalassemia), 150 had thalassemia trait with concomitant iron deficiency or anemia of chronic disease, and 36 had other diseases. We investigated 25 discriminant formulas that only use hematologic parameters available on all analyzers; formulas with more advanced parameters were disregarded. The diagnostic performance was investigated using ROC analysis. RESULTS: The three best performing formulas were the Jayabose (RDW index), Janel (11T), and Green and King formulas. The differences between them were not statistically significant (p>0.333), but each of them had significantly higher area under the ROC curve than any other formula. The Jayabose and Green and King formulas had the highest sensitivities: 0.917 both. The highest specificity, 0.925, was found for the Janel formula, which is a composite score of 11 other formulas. All investigated formulas performed significantly better in distinguishing ß- than α-thalassemia from iron deficiency. CONCLUSIONS: In our patient population, the Jayabose RDW index, the Green and King formula and the Janel 11T score are superior to all other formulas examined for distinguishing between thalassemia trait and iron deficiency anemia. We confirmed that all formulas perform much better in ß- than in α-thalassemia carriers and also that they incorrectly classify approximately 30% of thalassemia carriers with concomitant other anemia as not having thalassemia. The diagnostic performance of even the best formulas is not high enough for making a final thalassemia diagnosis, but in countries with limited resources, they can be helpful in identifying those patients who need further examinations for genetic anemia.

Practice guidelines for the diagnosis and management of microcytic anemias due to genetic disorders of iron metabolism or heme synthesis.

During recent years, our understanding of the pathogenesis of inherited microcytic anemias has gained from the identification of several genes and proteins involved in systemic and cellular iron metabolism and heme syntheses. Numerous case reports illustrate that the implementation of these novel molecular discoveries in clinical practice has increased our understanding of the presentation, diagnosis, and management of these diseases. Integration of these insights into daily clinical practice will reduce delays in establishing a proper diagnosis, invasive and/or costly diagnostic tests, and unnecessary or even detrimental treatments. To assist the clinician, we developed evidence-based multidisciplinary guidelines on the management of rare microcytic anemias due to genetic disorders of iron metabolism and heme synthesis. These genetic disorders may present at all ages, and therefore these guidelines are relevant for pediatricians as well as clinicians who treat adults. This article summarizes these clinical practice guidelines and includes background on pathogenesis, conclusions, and recommendations and a diagnostic flowchart to facilitate using these guidelines in the clinical setting.

Evaluation of the hypochromic erythrocyte and reticulocyte hemoglobin content provided by the Sysmex XE-5000 analyzer in diagnosis of iron deficiency erythropoiesis.

BACKGROUND: Iron deficiency represents the most frequent cause of anemia. To diagnose iron deficiency some biochemical tests such as serum ferritin and the transferring saturation percent (TSAT%) are usually used. Recently, some hematological parameters such as mean reticulocyte hemoglobin content (CHr or Ret-He) and percentage of hypochromic RBCs (Hypo% or %Hypo-He) were proposed as alternative to biochemical tests. In this study, the analytic performance and the diagnostic efficiency of these two parameters provided by Sysmex XE5000 analyzer on iron deficiency patients with or without anemia (IDA and ID, respectively) were evaluated. METHODS: One hundred and sixty-four healthy adults, 58 with IDA, 21 with iron depleted stores (ID), 23 with ß-thalassemia trait, and 24 with non iron deficiency anemia were selected. The gold standard used to define iron deficiency was the coexistence of serum ferritin below 15 µg/L (12 in women) and TSAT <16%. RESULTS: For %Hypo-He, the best cut-off value for both IDA and ID is 0.9% while for Ret-He is 30.6 pg. For both parameters the performance was better to diagnose IDA (AUC, 0.96 and 0.98) than ID (AUC, 0.93 and 0.95). The Ret-He behavior was always slightly better than that of %Hypo-He. CONCLUSIONS: The use of these two parameters is useful to detect iron deficiency conditions if the hemoglobin synthesis has already been compromised.

Comparison of serum paraoxonase and arylesterase activities between iron deficiency anemia patients and chronic kidney disease patients with anemia.

OBJECTIVE: Altered paraoxonase (PON) and arylesterase (ARE) activities have been shown in anemic chronic kidney disease (CKD) patients and in iron deficiency anemia (IDA) patients. Whether accompanying anemia alone is responsible for this diminished PON and ARE activities in CKD patients or an additive factor for this is not well studied. Therefore, we tried to clarify this issue here. METHODS: A total of 82 subjects that consisted of 19 patients with IDA (group 1), 23 anemic CKD patients (group 2), and 40 age and sex matched healthy subjects (group 3) were enrolled. Carotid intima media thickness (CIMT), serum total thiol (-SH), PON, and ARE activities of the participants were analyzed. RESULTS: Group 2 patients had significantly lowest serum levels of Total -SH, PON and ARE. Further comparison showed that total -SH, PON and ARE levels were lower in group 1 than group 3 (p = 0.0001 in both). Regarding comparison of group 1 and 2, only serum ARE levels were significantly lower in group 2 (p = 0.001). PON activity was not different between group 1 and group 2 whereas ARE activity was lower in group 2 than groups 1 and 3. In addition, correlation analysis showed that CIMT was negatively correlated with PON and ARE. CONCLUSIONS: This markedly decreased ARE activity in CKD patients, which could not be explained by the anemia alone, may have a role in the pathogenesis of increased atherosclerosis in such patients. Still further studies are needed to certain this.

Diagnosis of iron-deficient states.

The diagnosis of iron deficiency anemia is typically straightforward, especially when classic biochemical and hematological changes are present in a subject at risk. It can be challenging in the presence of diseases or when it is due to inherited defects of iron metabolism. The identification of iron deficiency prior to anemia development is also difficult. New hematological parameters such as reticulocyte Hb content have expanded the classic ones such as MCV, MCH and MCHC. A variety of hematology analyzers now provide novel parameters to assess cellular hypochromia and microcytosis in both reticulocytes and mature red blood cells. The repertoire of biochemical markers has also been expanded, with iron, transferrin and ferritin being supplemented by circulating transferrin receptor and hepcidin. Molecular identification of functional variants of key iron metabolism determinants has provided explanations for the heritability of some iron metabolism biomarkers. Genetic defects in some of these molecules are responsible for hereditary microcytic anemias, also called atypical microcytic anemias. In this review, we examine the most significant hematological and biochemical markers for iron metabolism, as well as relevant genetic polymorphisms and defects affecting iron handling.

Discriminant indices for distinguishing thalassemia and iron deficiency in patients with microcytic anemia: a meta-analysis.

BACKGROUND: More than 40 mathematical indices have been proposed in the hematological literature for discriminating between iron deficiency anemia and thalassemia trait in subjects with microcytic red blood cells (RBCs). None of these discriminant indices is 100% sensitive and specific and also the ranking of the discriminant indices is not consistent. Therefore, we decided to conduct the first meta-analysis of the most frequently used discriminant indices. METHODS: An extensive literature search yielded 99 articles dealing with 12 indices that were investigated five or more times. For each discriminant index we calculated the diagnostic odds ratio (DOR) and summary ROC analysis was done for comparing the performance of the indices. RESULTS: The ratio of microcytic to hypochromic RBCs (M/H ratio) showed the best performance, DOR=100.8. This was significantly higher than that of all other indices investigated. The RBC index scored second (DOR=47.0), closely followed by the Sirdah index (DOR=46.7) and the Ehsani index (DOR=44.7). Subsequently, there was a group of four indices with intermediate and three with lower DOR. The lowest performance (DOR=6.8) was found for the RDW (Bessman index). Overall, the indices performed better for adults than for children. CONCLUSIONS: The M/H ratio outperformed all other discriminant indices for discriminating between iron deficiency anemia and thalassemia trait. Although its sensitivity and specificity are not high enough for making a definitive diagnosis, it is certainly of value for identifying those subjects with microcytic RBC in whom diagnostic tests for confirming thalassemia are indicated.

A 21 Nucleotide Duplication on the α1- and α2-Globin Genes Involves a Variety of Hypochromic Microcytic Anemias, From Mild to Hb H Disease.

α-Thalassemia (α-thal) is a common genetic disorder in Iran and many parts of the world. Genetic defects in the α-globin gene cluster can result in α-thal that may develop into a clinical phenotype varying from almost asymptomatic to a lethal hemolytic anemia. Loss of one functional α gene, indicated as heterozygous α(+)-thal, shows minor hematological abnormalities. Homozygosity for α(+)- or heterozygosity for α(0)-thal have more severe hematological abnormalities due to a markedly reduced α chain output. At the molecular level, the absence of three α-globin genes resulting from the compound heterozygous state for α(0)- and α(+)-thal, lead to Hb H disease. Here we present a 21 nucleotide (nt) duplication consisting of six amino acids and 3 bp of intronic sequence at the exon-intron boundary, in both the α-globin genes, detected by direct DNA sequencing. This duplication was identified in three patients originating from two different Iranian ethnic groups and one Arab during more than 12 years. The clinical presentation of these individuals varies widely from a mild asymptomatic anemia (heterozygote in α1-globin gene) to a severely anemic state, diagnosed as an Hb H individual requiring blood transfusion (duplication on the α2-globin gene in combination with the - -(MED) double α-globin gene deletion). The third individual, who was homozygous for this nt duplication on the α1-globin gene, showed severe hypochromic microcytic anemia and splenomegaly. In the last decade, numerous α-globin mutations have demonstrated the necessity of prenatal diagnosis (PND) for α-thal, and this study has contributed another mutation as important enough that needs to be considered.

Hb G-Waimanalo [A1] or α64(E13)Asp→Asn (α1) (HBA1: c.193G>A) Observed in a Bulgarian Family.

The abnormal hemoglobin (Hb) with an aspartic acid to asparagine substitution at α64 has been found on both the α2- and α1-globin genes. It has been described in many different populations under different names, but never in Bulgaria. Using the recently proposed nomenclature, Hb G-Waimanalo [A1] refers to the HBA1: c.193G > A, while Hb G-Waimanalo [A2] refers to the HBA2: c.193G > A mutation. Here, we present the first family from Bulgaria with Hb G-Waimanalo [A1].

Hb G-Waimanalo [A1] [α64(E13)Asp→Asn; HBA1: c.193 G > A] with Decreased Oxygen Affinity.

A clinically asymptomatic 12-year-old girl showed microcytosis in routine examination. Cation exchange high performance liquid chromatography (HPLC), revealed two additional peaks eluting after Hb A and DNA sequencing uncovered a novel heterozygous mutation at codon 64 of the α1-globin gene. The hemoglobin (Hb) variant was annotated as Hb G-Waimanalo [A1]. Further analyses demonstrated a decreased oxygen affinity Hb compared to the normal Hb configuration.