Clinical and hematologic aspects of hemoglobin E beta-thalassemia

Rapid Identification of β-Thalassemia, Hb E, and High Hb F Determinants Using a High-Resolution Melting Analysis: Application in Prenatal Diagnosis in Southern Thailand

β-thalassemia (thal), hemoglobin (Hb) E, and high Hb F determinants, which are caused by mutations in the β-globin gene cluster, are common genetic disorders in Thailand and Southeast Asia. Prenatal diagnosis is essential for couples at risk to identify severe forms, including homozygous β-thal and Hb E/β-thal. Conventional methods, including reverse dot-blot hybridization and gap-polymerase chain reaction (PCR) for genotyping of point and large deletion mutations, require post-PCR steps, which are time-consuming and costly. This study aimed to develop a rapid and efficient method using monoplex high-resolution melting (HRM) analysis for genotyping of Hb E and 11 β-thal mutations; multiplex HRM analysis for identifying six deletional mutations, including two β0-thal mutations (3.5 and 45 kb deletion); and a novel method for detecting four high Hb F determinants, namely, δβ0-thal (12.5 kb deletion), HPFH6, Indian inv-del (Aγδβ)0-thal, and Thai del-inv-ins (Aγδβ)0-thal. The developed assays were validated using 182 blinded fetal DNA samples with 41 β-thal genotypes. Different HRM patterns were observed among wild-type, heterozygote, homozygote, and compound heterozygote genotypes. Six deletional mutations showed specific melt curves. This technique demonstrated 100% concordance with conventional methods. The assay showed 100% sensitivity, specificity, and positive and negative predictive values within the limit of detection at DNA concentrations of 8.0 ng/reaction. Finally, this developed assay was efficient in identifying both point mutations and large deletion, convenient, rapid, and cost-effective and did not require post-PCR steps. Thus, this technique has potential for application in prenatal diagnosis of thal and can inform prevention and control programs.

α-Globin mutations and Genetic Variants in γ-globin Promoters are Associated with Unelevated Hemoglobin F Expression of Atypical β0-thalassemia/HbE

BACKGROUND

Excessive expression of hemoglobin F (HbF) is a characteristic feature and important diagnostic marker of β0-thalassemia/HbE disease. However, some patients may exhibit low-HbF levels, leading to misdiagnosis and precluding genetic counseling. The genetic factors influencing these differences in HbF expression in this atypical disease are not completely understood.

AIMS

To investigate determinants contributing to the non-elevation of HbF expression in β0-thalassemia/HbE disease.

METHODS

We studied 231 patients with β0-thalassemia/HbE confirmed by DNA analysis; classified them into the low-HbF (n = 62) and high-HbF (n = 169) groups; analyzed hematological parameters and hemoglobin levels in both groups; and characterized mutations in β- and α-globin genes and genetic variants in γ-globin promoters.

RESULTS

Both groups showed similar rates of type β0-thalassemia mutations but significantly different proportions of α-globin mutations: approximately 88.7% (95% confidence interval [CI] = 66.8-115.5) and 39.1% (95% CI = 30.2-49.7) in the low- and high-HbF groups, respectively. The results revealed single-nucleotide polymorphisms (SNPs) at -158 (C>T) in the Gγ-globin promoters and novel SNPs at the 5' untranslated region position 25 (G>A) in Aγ-globin promoters. The distribution of CC genotypes of the Gγ-globin promoter in the low-HbF group was significantly higher than that in the high-HbF group.

CONCLUSIONS

Cases with HbE predominance with low-HbF levels and undetectable HbA may not be as conclusive as those with homozygous HbE until DNA analysis is performed. Concomitant inheritance of α-thalassemia is an important inherent factor modifying HbF expression in a typical β0-thalassemia/HbE, and SNPs with the CC genotype in the Gγ-globin promoter may indicate unelevated HbF expression in patients with this disease.

The Characteristics of Compound Heterozygosity for Hemoglobin G-Makassar with Hb E in Malaysia

Background

Human hemoglobin of G-Makassar and hemoglobin E (Hb E) are hemoglobin variants that affect Beta (β) globin. Hb G-Makassar is a very rare variant while Hb E is estimated to affect at least one million people worldwide. Both Hb G-Makassar and Hb E can be inherited in the heterozygous, homozygous or compound heterozygous state. This case series describes the characteristics of four individuals with compound heterozygosity for Hb G-Makassar/Hb E cases in Malaysia. To the best of our knowledge, these are the only four individuals with this genotype reported in the literature.

Case Series

We present four cases of compound heterozygosity for Hb G-Makassar/Hb E identified from October 2014 to January 2021. All the cases were incidental findings whereby the screening Hb analysis showed the presence of peaks in both Hb S and Hb E zones on capillary electrophoresis (CE) and cation-exchange high-performance liquid chromatography (HPLC). Molecular analysis confirmed the findings of compound heterozygous Hb G-Makassar/Hb E. Two cases had a history of anemia secondary to unrelated conditions that resolved with treatment of the underlying cause. The other two cases were asymptomatic individuals who were detected through Malaysia's National Thalassemia Screening program. On the last follow-up, all the individuals were well, non-transfusion dependent, and had no reported history of chronic anemia, bleeding, hemolysis or thromboembolism complications.

Conclusion

The cases reported here highlight the possibilities for rare compound heterozygous states in multi-ethnicity populations such as Malaysia. Compound heterozygous Hb G-Makassar/Hb E individuals are clinically silent with laboratory values suggesting microcytic and hypochromic red blood cells. Further local epidemiology or population studies with genotyping tests are required for a better understanding of the diversity of its clinical phenotype.

Up-regulation of microRNA 101-3p during erythropoiesis in β-thalassemia/HbE

Ineffective erythropoiesis is the main cause of anemia in β-thalassemia. The crucial hallmark of ineffective erythropoiesis is the high proliferation of erythroblast. microRNA (miR/miRNA) involves several biological processes, including cell proliferation and erythropoiesis. miR-101 was widely studied and associated with proliferation in several types of cancer. However, the miR-101-3p has not been studied in β-thalassemia/HbE. Therefore, this study aims to investigate the expression of miR-101-3p during erythropoiesis in β-thalassemia/HbE. The results showed that miR-101-3p was upregulated in the erythroblast of β-thalassemia/HbE patients on day 7, indicating that miR-101-3p may be involved with high proliferation in β-thalassemia/HbE. Therefore, the mRNA targets of miR-101-3p including Rac1, SUB1, TET2, and TRIM44 were investigated to determine the mechanisms involved with high proliferation of β-thalassemia/HbE erythroblasts. Rac1 expression was significantly reduced at day 11 in severe β-thalassemia/HbE compared to normal controls and mild β-thalassemia/HbE. SUB1 gene expression was significantly lower in severe β-thalassemia/HbE compared to normal controls at day 9 of culture. For TET2 and TRIM44 expression, a significant difference was not observed among normal and β-thalassemia/HbE. However, the high expression of miR-101-3p at day 7 and these target genes was not correlated, suggesting that this miRNA may regulate ineffective erythropoiesis in β-thalassemia/HbE via other target genes.

Molecular understanding of unusual HbE-β+-thalassemia with Hb phenotype similar to HbE heterozygote: simple and rapid differentiation using HbE levels

BACKGROUND

Low HbF expression in HbE-β+-thalassemia may lead to misdiagnosis of HbE heterozygosity. We aimed to characterize the β- and α-globin genes and the modifying factors related to HbF expression in patients with an Hb phenotype similar to that of HbE heterozygotes. Furthermore, screening tools for differentiating HbE-β+-thalassemia from HbE heterozygotes have been investigated.

PARTICIPANTS AND METHODS

A total of 2133 participants with HbE and HbA with varying HbF levels were recruited. Polymerase chain reaction-based DNA analysis and sequencing were performed to characterize β- and α-globin genes. DNA polymorphism at position -158 nt 5' to Gγ-globin was performed by XmnI restriction digestion. Receiver operating characteristic (ROC) curves were constructed using the area under the curve (AUC). Cutoff values of HbA2, HbE, and HbF levels for the differentiation of HbE-β+-thalassemia from HbE heterozygotes were determined.

RESULTS

Five β+-thalassemia mutations trans to βE-gene (β-87(C>A), β-31(A>G), β-28(A>G), β19(A>G), and β126(T>G)) were identified in 79 patients. Among these, 54 presented with low HbF levels, and 25 presented with high HbF levels. ROC curve analysis revealed an excellent AUC of 1.000 (95% confidence interval:1.000-1.000) for HbE levels, and a cut-off point of ≥35.0% had 100.0% sensitivity, specificity, and Youden's index for differentiating HbE-β+-thalassemia from HbE heterozygotes. The proportion of α-thalassemia mutations was 46.3 and 8.0% among HbE-β+-thalassemia patients with low and high HbF levels, respectively. Two rare α-thalassemia mutations (Cap +14(C>G) and initiation codon (ATG>-TG)) of α2-globin genes were identified. The genotype and allele of the polymorphism at -158 nt 5' to Gγ-globin was found to be negatively associated with HbF expression.

CONCLUSIONS

HbE-β+-thalassemia cannot be disregarded until appropriate DNA analysis is performed, and the detection of α-thalassemia mutations should always be performed under these conditions. An HbE level ≥35.0% may indicate screening of samples for DNA analysis for HbE-β+-thalassemia diagnosis.

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.

Extramedullary Hematopoiesis Visualized on FDG-PET/CT in a Patient with Beta-Thalassemia

Beta-thalassemia is an inherited blood disorder caused by reduced or absent synthesis of the beta chains of hemoglobin, resulting in decreased hemoglobin production. Symptoms depend on the type of beta-thalassemia ranging from no symptoms to severe illness. Ineffective erythropoiesis leads to a sequence of events responsible for bone marrow expansion, anemia, hemolysis, splenomegaly, increased iron absorption, and sometimes extramedullary hematopoiesis (EMH). We report an interesting case with EMH visualized on FDG-PET/CT and where FDG-PET/CT has also found the focus of a severe infection in a patient with beta-thalassemia.

A Curious Case of Suspicious Lymphadenopathy in a Hereditary Spherocytosis Patient Reported as Extramedullary Hematopoiesis

We present a case of a 23-year-old male patient with complaints of fever, cough, and persistent anemia for the past 6 months and with a known history of hereditary spherocytosis. Computed tomography (CT) thorax demonstrated multiple paravertebral lesions in the bilateral thoracic cavities, suggestive of lymphadenopathy; subsequently, 18Flurodeoxyglucose PET/CT was done with suspicion of lymphoma, which showed no significant metabolic activity in those lesions. Thus, in view of clinical and metabolic status, lesions were considered extramedullary hematopoiesis (EMH). This case highlights the importance of considering EMH, while interpreting suspicious lymphadenopathy in cases of chronic anemia and also possible scan findings in the same.

Genetic predictions of life expectancy in southern Thai patients with β0‑thalassemia/Hb E

The types of β-thalassemia mutations, α-thalassemia interactions, and Hb F-associated SNPs have been described in association with variable disease phenotypes. This study aimed to determine the updated spectrum of β-thalassemia mutations and evaluate the contribution of primary and secondary genetic modifiers and SNPs to disease severity, age at onset, and predicted life expectancy in southern Thai β-thalassemia patients. A total of 181 β-thalassemia patients were enrolled and 135 β⁰-thalassemia/Hb E patients without α-thalassemia interactions were divided into three categories according to disease severity, age at onset, and predicted life expectancy. A total of 16 β-thalassemia mutations were identified in this study, and the three most common β-thalassemia mutations accounted for 61.4% of all mutations. It was also found that the XmnI polymorphism and rs2071348 were associated with age at onset and the predicted life expectancy. More than 82% of β⁰-thalassemia/Hb E patients with CC genotype (XmnI) were 3 years old or younger at onset. Additionally, >90% of the higher predicted life expectancy in β⁰-thalassemia/Hb E patients had the T allele of XmnI. Therefore, genetic prediction for age at onset and life expectancy is beneficial and practical during prenatal diagnosis or newborn screening for better genetic counseling and optimal management.

Ultrasensitive electrochemical molecularly imprinted sensor based on AuE/Ag-MOF@MC for determination of hemoglobin using response surface methodology

Considering the importance of determining the levels of hemoglobin (Hb) as a vital protein in red blood cells, in this work a highly sensitive electrochemical sensor was developed based on a gold electrode (AuE) modified with Ag metal-organic framework mesoporous carbon (Ag-MOF@MC) and molecularly imprinted polymers (MIPs). To that end, the MIP layer was formed on the Ag-MOF@MC by implanting Hb as the pattern molecule during the polymerization. The modified electrode was designed using electrochemical approaches including differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Using a response level experimental design method, the most important parameters affecting the reaction of the sensing system including pH, incubation time, and scanning rate were optimized. Following the same route, the Hb concentration, pH, temperature, and elution times were optimized to prepare the imprinted polymer layer on the Ag-MOF@MC surface. By exploiting DPV techniques based on the optimal parameters, the electrochemical response of the AuE/Ag-MOF@MC-MIPs for Hb determination was recorded in a wide linear dynamic range (LDR) of 0.2 pM to 1000 nM, with a limit of detection (LOD) of 0.09 pM. Moreover, the Ag-MOF@MC-MIP sensing system showed good stability, high selectivity, and acceptable reproducibility for Hb determination. The sensing system was successfully applied for Hb determination in real blood samples, and the results were compared with those of the standard methods for Hb determination. Acceptable recovery (99.0%) and RDS% (4.6%) confirmed the applicability and reliability of the designed Hb sensing system.

Curcuminoids supplementation ameliorates iron overload, oxidative stress, hypercoagulability, and inflammation in non-transfusion-dependent β-thalassemia/Hb E patients

Curcuminoids, polyphenol compounds in turmeric, possess several pharmacological properties including antioxidant, iron-chelating, and anti-inflammatory activities. Effects of curcuminoids in thalassemia patients have been explored in a limited number of studies using different doses of curcuminoids. The present study aims to evaluate the effects of 24-week curcuminoids supplementation at the dosage of 500 and 1000 mg/day on iron overload, oxidative stress, hypercoagulability, and inflammation in non-transfused β-thalassemia/Hb E patients. In general, both curcuminoids dosages significantly lowered the levels of oxidative stress, hypercoagulability, and inflammatory markers in the patients. In contrast, reductions in iron parameter levels were more remarkable in the 1000 mg/day group. Subgroup analysis revealed that a marker of hypercoagulability was significantly decreased only in patients with baseline ferritin ≤ 1000 ng/ml independently of curcuminoids dosage. Moreover, the alleviation of iron loading parameters was more remarkable in patients with baseline ferritin > 1000 ng/ml who receive 1000 mg/day curcuminoids. On the other hand, the responses of oxidative stress markers were higher with 500 mg/day curcuminoids regardless of baseline ferritin levels. Our study suggests that baseline ferritin levels should be considered in the supplementation of curcuminoids and the appropriate curcuminoids dosage might differ according to the required therapeutic effect. Thai Clinical Trials Registry (TCTR): TCTR20200731003; July 31, 2020 "retrospectively registered".

Comprehensive screening for coexisting heterozygous α0-thalassemia in hemoglobin E trait

Objectives: A sensitive screening for the coexistence of α⁰-thalassemia and the hemoglobin E (Hb E) trait is important to identify at-risk couples for hydrops fetalis. However, previous cutoff values have shown a positive predictive value (PPV) of only 50% or less. This study aimed to define more specific indicators to reduce the need for DNA tests. Methods: Patients with Hb E trait, as diagnosed by high performance liquid chromatography (HPLC) and/or isoelectric focusing (IEF) techniques, were tested for α⁰-thalassemia and α⁺-thalassemia deletions using multiplex gap polymerase chain reaction. Iron deficiency anemia (IDA) were excluded using a red cell distribution width (RDW) of more than 14.5%. Results: From 390 specimens, suitable cutoff values showing a 100% sensitivity for detection of heterozygous α⁰-thalassemia were an Hb E level of less than 22% by HPLC, a mean corpuscular volume (MCV) of less than 72 fL, and a mean corpuscular hemoglobin (MCH) level of less than 22.5 pg. Comparable results were obtained in the validation cohort (N = 179). Using a combination of Hb E with either MCV or MCH cutoff points gave a PPV of 76.2% and 77.4%, respectively. Discussion: IDA was reported to interfere with Hb E level. In this study, we excluded IDA using RDW of more than 14.5% to enhance the test specificity. Conclusion: Lower cutoff screening values can be used to exclude α⁰-thalassemia in the Hb E trait yielding a higher specificity in a normal RDW condition. This can save the cost and labor of DNA testing.

Genotype-Phenotype Correlation of β-Thalassemia in Malaysian Population: Toward Effective Genetic Counseling

Effective prevention of β-thalassemia (β-thal) requires strategies to detect at-risk couples. This is the first study attempting to assess the prevalence of silent β-thal carriers in the Malaysian population. Hematological and clinical parameters were evaluated in healthy blood donors and patients with β-thal trait, Hb E (HBB: c.79G>A)/β-thal and β-thal major (β-TM). β-Globin gene sequencing was carried out for 52 healthy blood donors, 48 patients with Hb E/β-thal, 34 patients with β-TM and 38 patients with β-thal trait. The prevalence of silent β-thal carrier phenotypes found in 25.0% of healthy Malaysian blood donors indicates the need for clinician's awareness of this type in evaluating β-thal in Malaysia. Patients with β-TM present at a significantly younger age at initial diagnosis and require more blood transfusions compared to those with Hb E/β-thal. The time at which genomic DNA was extracted after blood collection, particularly from patients with β-TM and Hb E/β-thal, was found to be an important determinant of the quality of the results of the β-globin sequencing. Public education and communication campaigns are recommended as apparently healthy individuals have few or no symptoms and normal or borderline hematological parameters. β-Globin gene mutation characterization and screening for silent β-thal carriers in regions prevalent with β-thal are recommended to develop more effective genetic counseling and management of β-thal.

Iron status and inherited haemoglobin disorders modify the effects of micronutrient powders on linear growth and morbidity among young Lao children in a double-blind randomised trial

Some studies found that providing micronutrient powder (MNP) causes adverse health outcomes, but modifying factors are unknown. We aimed to investigate whether Fe status and inherited Hb disorders (IHbD) modify the impact of MNP on growth and diarrhoea among young Lao children. In a double-blind controlled trial, 1704 children of age 6–23 months were randomised to daily MNP (with 6 mg Fe plus fourteen micronutrients) or placebo for about 36 weeks. IHbD, and baseline and final Hb, Fe status and anthropometrics were assessed. Caregivers provided weekly morbidity reports. At enrolment, 55·6 % were anaemic; only 39·3 % had no sign of clinically significant IHbD. MNP had no overall impact on growth and longitudinal diarrhoea prevalence. Baseline Hb modified the effect of MNP on length-for-age (LAZ) (P for interaction = 0·082). Among children who were initially non-anaemic, the final mean LAZ in the MNP group was slightly lower (–1·93 (95 % CI –1·88, –1·97)) v. placebo (–1·88 (95 % CI –1·83, –1·92)), and the opposite occurred among initially anaemic children (final mean LAZ –1·90 (95 % CI –1·86, –1·94) in MNP v. –1·92 (95 % CI –1·88, –1·96) in placebo). IHbD modified the effect on diarrhoea prevalence (P = 0·095). Among children with IHbD, the MNP group had higher diarrhoea prevalence (1·37 (95 % CI 1·17, 1·59) v. 1·21 (95 % CI 1·04, 1·41)), while it was lower among children without IHbD who received MNP (1·15 (95 % CI 0·95, 1·39) v. 1·37 (95 % CI 1·13, 1·64)). In conclusion, there was a small adverse effect of MNP on growth among non-anaemic children and on diarrhoea prevalence among children with IHbD.

Increased ferritin levels in non-transfusion-dependent β°-thalassaemia/HbE are associated with reduced CXCR2 expression and neutrophil migration

Severe bacterial infection is a major complication causing morbidity and mortality in β-thalassaemia/HbE patients. Innate immunity constitutes the first line of defence against bacterial infection. This study aimed to comprehensively investigate the innate immune phenotype and function related to factors predisposing to infection in non-transfusion-dependent (NTD) β°-thalassaemia/HbE patients. Twenty-six patients and 17 healthy subjects were recruited to determine complement activity (C3, C4, mannose-binding lectin and CH50) and surface receptor expression including markers of phagocytosis (CD11b, CD16 and C3bR), inflammation (C5aR) and migration (CD11b, CXCR1 and CXCR2) on neutrophils and monocytes. In addition, phagocytosis and oxidative burst activity of neutrophils and monocytes against Escherichia coli and neutrophil migration were examined. Decreased C3 and surface expression of CD11b and C3bR on neutrophils were found in patients. However, phagocytosis of neutrophils in patients was still in the normal range. Interestingly, patients displayed a significant reduction of surface expression of CXCR2 [1705 ± 217 mean fluorescent intensity (MFI)] on neutrophils, leading to impaired neutrophil migration (9·2 ± 7·7%) when compared to neutrophils from healthy subjects (2261 ± 627 MFI and 27·8 ± 9% respectively). Moreover, surface expression of CXCR2 on neutrophils was associated with splenectomy status, serum ferritin and haemoglobin levels. Therefore, impaired neutrophil migration could contribute to the increased susceptibility to infection seen in NTD β°-thalassaemia/HbE patients.

Clinical utility of combined preimplantation genetic testing methods in couples at risk of passing on beta thalassemia/hemoglobin E disease: A retrospective review from a single center

Thalassemia and hemoglobinopathy is a group of hereditary blood disorder with diverse clinical manifestation inherited by autosomal recessive manner. The Beta thalassemia/Hemoglobin E disease (HbE/βthal) causes a variable degree of hemolysis and the most severe form of HbE/βthal disease develop a lifelong transfusion-dependent anemia. Preimplantation genetic testing (PGT) is an established procedure of embryo genetic analysis to avoid the risk of passing on this particular condition from the carrier parents to their offspring. Preimplantation genetic testing for chromosomal aneuploidy (PGT-A) also facilitates the selection of embryos without chromosomal aberration resulting in the successful embryo implantation rate. Herein, we study the clinical outcome of using combined PGT-M and PGT-A in couples at risk of passing on HbE/βthal disease. The study was performed from January 2016 to December 2017. PGT-M was developed using short tandem repeat linkage analysis around the beta globin gene cluster and direct mutation testing using primer extension-based mini-sequencing. Thereafter, we recruited 15 couples at risk of passing on HbE/βthal disease who underwent a combined total of 22 IVF cycles. PGT was performed in 106 embryos with a 3.89% allele drop-out rate. Using combined PGT-M and PGT-A methods, 80% of women obtained satisfactory genetic testing results and were able to undergo embryo transfer within the first two cycles. The successful implantation rate was 64.29%. PGT accuracy was evaluated by prenatal and postnatal genetic confirmation and 100% had a genetic status consistent with PGT results. The overall clinical outcome of successful live birth for couples at risk of producing offspring with HbE/βthal was 53.33%. Conclusively, combined PGT-M and PGT-A is a useful technology to prevent HbE/βthal disease in the offspring of recessive carriers.

Abnormal red blood cell morphological changes in thalassaemia associated with iron overload and oxidative stress

AIMS

Iron overload is a major factor contributing to the overall pathology of thalassaemia, which is primarily mediated by ineffective erythropoiesis and shorter mature red blood cell (RBC) survival. Iron accumulation in RBCs generates reactive oxygen species (ROS) that cause cellular damage such as lipid peroxidation and RBC membrane deformation. Abnormal RBCs in patients with thalassaemia are commonly known as microcytic hypochromic anaemia with poikilocytosis. However, iron and ROS accumulation in RBCs as related to RBC morphological changes in patients with thalassaemia has not been reported.

METHODS

Twenty-one patients with thalassaemia, including HbH, HbH with Hb Constant Spring and β-thalassaemia/HbE (splenectomy and non-splenectomy) genotypes, and five normal subjects were recruited. RBC morphology was analysed by light and scanning electron microscopy. Systemic and RBC iron status and oxidative stress were examined.

RESULTS

Decreased normocytes were observed in the samples of patients with thalassaemia, with RBC morphological abnormality being related to the type of disease (α-thalassaemia or β-thalassaemia) and splenic status. Target cells and crenated cells were mainly found in splenectomised patients with β-thalassaemia/HbE, while target cells and teardrop cells were found in non-splenectomised patients. Patients with thalassaemia had high levels of serum ferritin, red cell ferritin and ROS in RBCs compared with normal subjects (p<0.05). Negative correlations between the amount of normocytes and serum ferritin (r_s=-0.518, p=0.011), red cell ferritin (r_s=-0.467, p=0.025) or ROS in RBCs (r_s=-0.672, p<0.001) were observed.

CONCLUSIONS

Iron overload and its consequent intracellular oxidative stress in RBCs were associated with reduce normocytes in patients with thalassaemia.

Applicability of a clinical scoring criteria for disease severity of ß-thalassemia/hemoglobin E in Indonesia

Background: β-thalassemia/HbE presents with a variety of clinical symptoms, from asymptomatic to severe, requiring routine transfusion. However, there is currently no agreed classification system to stratify patients based on clinical severity of β-thalassemia/HbE in the Indonesian population. Thailand has already established a classification system, and this study aimed to identify the applicability of the Thailand clinical scoring criteria to determine the severity of β-thalassemia/HbE in the Indonesian population.Methods: This descriptive study was conducted by evaluating patients with β-thalassemia/HbE, who were classified into mild, moderate, or severe groups based on the Thailand clinical scoring criteria.Results: A total of 293 subjects with β-thalassemia/HbE were included. Based on this clinical scoring criteria, it was found that only 21.5% of patients were classified as mild, and the remaining 35.5% and 44% were classified as moderate and severe respectively. Approximately 68.2% of the subjects in the severe group received transfusion at <4 years old, while only 10% of those in the mild group were transfused at the same age. In the mild group, only 10% of the subjects underwent routine transfusion, compared to 98.4% of the subjects in the severe group. In addition, only 27% of the subjects in the mild group showed stunted growth, while that in the moderate and severe groups were 54.5% and 86.8%, respectively.Conclusion: Thailand clinical scoring criteria is able to determine the severity of Indonesia thalassemia patient which needs further management, i.e. transfusion and observation of stunted growth. This scoring system will help provide the provision of the most ideal management for the groups of patients based on their requirements.

Interaction between Hb E and Hb Yala (HBB:c.129delT); a novel frameshift beta globin gene mutation, resulting in Hemoglobin E/β0 thalassemia

OBJECTIVES

There are more than 200 known mutations found in patients with β-thalassemia, a possibility to identify an unknown or novel mutation becomes less possible. Here, we report a novel mutation in a patient from Thailand who presented with chronic hemolytic anemia.

METHODS

A comprehensive hematology and DNA analysis was applied in the index patient and her mother.

RESULTS

Hematological and hemoglobin analyses were consistent with the clinical diagnosis of Hb E/β⁰-thalassemia. However, we could find only Hb E heterozygous mutation using our common polymerase chain reaction-based mutation detection of the β-globin genes. Furthermore, the molecular analysis demonstrated a novel T-deletion at codon 42 of the second exon of the β-globin gene which we named 'Hb Yala' according to the origin of this index family.

DISCUSSION

This mutation was assumed to generate a truncated β-globin chain terminating at codon 60 with possible unstable variant leading to a 'null' or β⁰-thalassemia. However, the clinical phenotype was surprisingly mild and no other ameliorating genetic factors, including co-inheritance of α-thalassemia and high propensity of Hb F by Xmn I polymorphism, were found.

CONCLUSION

This report has provided evidence that genotype-phenotype correlation in thalassemia syndromes is highly complex and a correct clinical severity classification of thalassemia should be mainly based on clinical evaluation.

Plasma microRNA-451 as a novel hemolytic marker for β0-thalassemia/HbE disease

In Southeast Asia, particularly in Thailand, β0-thalassemia/hemoglobin E (HbE) disease is a common hereditary hematological disease. It is associated with pathophysiological processes, such as the intramedullary destruction of immature erythroid cells and peripheral hemolysis of mature red blood cells. MicroRNA (miR) sequences, which are short non-coding RNA that regulate gene expression in a suppressive manner, serve a crucial role in human erythropoiesis. In the present study, the plasma levels of the erythroid-expressed miRNAs, miR‑451 and miR‑155, were analyzed in 23 patients with β0-thalassemia/HbE and 16 control subjects. Reverse transcription‑quantitative polymerase chain reaction analysis revealed significantly higher levels of plasma miR‑451 and miR‑155 in β0‑thalassemia/HbE patients when compared to the control subjects. Notably, among the β0‑thalassemia/HbE patients, a significant increase in miR‑451 levels was detected in severe cases when compared with mild cases. The levels of plasma miR‑451 correlated with reticulocyte and platelet counts. The results suggest that increased plasma miR‑451 levels may be associated with the degree of hemolysis and accelerated erythropoiesis in β0‑thalassemia/HbE patients. In conclusion, miR‑451 may represent a relevant biomarker for pathological erythropoiesis associated with β0-thalassemia/HbE.

Iron deficiency anemia interfering the diagnosis of compound heterozygosity for Hb constant spring and Hb Paksé: The first case report

BACKGROUND

Diagnosis of thalassemia or hemoglobinopathy concomitant with iron deficiency anemia (IDA) is challenging.

METHOD

We report a case of 43-year-old female whose diagnosis of compound heterozygosity for hemoglobin Constant Spring (HbCS) and Hb Paksé became apparent after the treatment of IDA.

RESULTS

Prior to treatment, Hb analysis using isoelectric focusing (IEF) showed HbA 95.6%, HbA₂ 2.7%, and HbCS 1.7% compatible with heterozygous HbCS. After 4 months of oral iron therapy resulting in an improved Hb level, her HbCS level was substantially increased to 8.7% on IEF suggesting homozygous HbCS. Subsequent DNA analysis using multiplex amplification refractory mutation system analysis revealed compound heterozygosity for HbCS and Hb Paksé.

CONCLUSION

This case demonstrated that IDA can significantly reduce HbCS/Hb Paksé levels and probably mask the diagnosis of homozygous HbCS, homozygous Hb Paksé or the compound heterozygosity for both hemoglobinopathies by hemoblogin analysis. The test should be repeated after resolution of IDA, or molecular testing should be performed to confirm the diagnosis.

Fetal hemoglobin regulation in β-thalassemia: heterogeneity, modifiers and therapeutic approaches

INTRODUCTION

Stress erythropoiesis induces fetal hemoglobin (HbF) expression in β-thalassemias, however the level of expression is highly variable. The last decade has seen dramatic advances in our understanding of the molecular regulators of HbF production and the genetic factors associated with HbF levels, leading to the promise of new methods of the clinical induction of HbF. Areas covered: This article will review the heterogeneity and genetic modifiers of HbF and HbF induction therapy in β-thalassemia. Expert commentary: One promising curative β-thalassemia therapy is to induce HbF synthesis in β-thalassemic erythrocytes to therapeutic levels before clinical symptom occurs. Further understanding of HbF level variation and regulation is needed in order to predict the response from HbF-inducing approaches.

Episodic spastic paraparesis successfully treated with unaided blood transfusions: a case report

BACKGROUND

Extramedullary haemopoiesis is a common compensatory phenomenon in most haemolytic anaemias. However, spinal cord compression due to extramedullary spinal epidural haemopoiesis is an extremely rare complication of thalassemia. In such situation patients present with paraplegia with a sensory level. Usual treatment options are surgery and/or radiotherapy.

CASE PRESENTATION

Here we report a 27 year old Sri Lankan Muslim male with haemoglobin E-Beta thalassaemia presented with episodic spastic paraparesis when he was anaemic which was dramatically responded to blood transfusion therapy.

CONCLUSION

Most of the reported cases with paraplegia have been treated with surgery with or without radiation therapy or radiation therapy alone. Our patient makes dramatic recovery after blood transfusion in each presentation.

Clinical, Hematological and Molecular Analysis of Homozygous Hb E (HBB: c.79G > A) in the Indian Population

Homozygous Hb E [β26(B8)Glu→Lys; HBB: c.79G > A] is a clinically mild disease with no significant symptoms. Very few studies are available on clinical variability in Hb E disorders. We report the profile of a series of homozygous Hb E patients in the Indian population. We analyzed various genetic factors that contribute to the heterogeneity in the phenotype of homozygous Hb E patients. Analysis of these parameters further enhances our understanding of the Hb E syndrome.

Does Profile of Hemoglobin Eβ-thalassemia Patients Change After Splenectomy? Experience of a Tertiary Thalassemia Care Centre in Eastern India

Hemoglobin Eβ-thalassemia is by far the commonest form of thalassemia intermedia. Its phenotype ranges from mild anemia to severe transfusion-dependency necessitating splenectomy in many patients. The present study aimed to systematically analyze both clinical as well as laboratory parameters in profile of Eβ-thalassemia patients after splenectomy in terms of transfusion requirement, infections and other complications. Retrospective study conducted over a period of 3 years included 72 cases of splenectomized Eβ-thalassaemia patients, considering decrease in transfusion requirements, new complications, antibiotic, anti-malarial prophylaxis and iron chelation therapy. Out of 1380 registered Eβ-thalassemia patients, 618 (44.78 %) were regularly transfused and 72(5.22 %) underwent splenectomy. Mean age of diagnosis was 10.3 years. Nineteen patients (26.4 %) underwent splenectomy between 5 and 10 years, 38 cases (52.7 %) between 10 and 20 years. The leading cause (51.39 %) for splenectomy was mechanical discomfort. Mean steady state hemoglobin raised from pre-splenectomy level of 5.43-6.8 gm/dl after splenectomy. Mean transfusion requirement reduced from 18.1 to 7.8 units/year. Mean serum ferritin level increased from 907.58 to 1,091.6 ng/ml. Post-splenectomy; 21 (29.17 %) patients developed facial deformities, 17 (23.6 %) delayed pubertal growth, 11 (15.28 %) venous thromboembolism, five (6.94 %) pulmonary hypertension and four (5.5 %) had extramedullary hematopoiesis. Five (6.96 %) patients had documented bacterial infections and two (2.78 %) suffered from malaria. Forty eight patients (66.67 %) started with iron chelation therapy; but majority (52.7 %) stopped. Major advantage of splenectomy is reduced transfusion requirement, though it cannot prevent skeletal abnormalities and delayed pubertal growth. In resource constraint countries like India, routine anti-malarial and antibacterial prophylaxis is not desirable; iron chelation therapy should be encouraged and ensured.

Antioxidant status in haemoglobin E carriers after acute and chronic strenuous exercises

Haemoglobin E (HbE), an unstable haemoglobin, is highly susceptible to oxidative damages. We examined how acute or chronic physiological challenge induced by exercise affects antioxidant response in HbE carriers. Two independent studies were conducted in individuals with HbE trait and paired normal Hb. In study 1, sedentary participants were tested in a graded maximal exercise and blood samples were collected before, immediately after, and 45 minutes after an acute exercise. Our data showed that erythrocyte glutathione peroxidase (GPx) activity failed to recover in HbE carriers after 45 minutes of rest. In study 2, athletes were trained in a 10-week strenuous training and blood samples were collected before and after training period. We found that athletes with HbE carriers showed a larger increase in plasma GPx activity compared to those with normal Hb. These data suggest that HbE carriers could cope with exercise-induced oxidative stress by adjusting endogenous antioxidant markers.

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

Context:

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

Aims and Objectives:

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

Subjects and Methods:

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

Statistical Analysis:

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

Result:

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

Conclusion:

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

Is hemoglobin e gene widely spread in the state of madhya pradesh in central India? Evidence from five typical families

Background

Red cell inherited hemoglobin (Hb) anomalies are commonly encountered in the central region of India. These cause a public health concern due to high level of morbidity, mortality, and fetal loss in the backward, underprivileged, and vulnerable people.

Purpose

To report five typical families of Hb E disorders for the first time detected and identified from various districts of the state of Madhya Pradesh in central India.

Methods

Out of a total of 447 couples/families referred from a tertiary hospital in central India for investigations of anemia/hemoglobinopathies during the period from March 2010 to February 2014, we came across five typical rare couples/families of Hb E disorders (1.1%) worthy of detailed investigations that we have reported here. Laboratory investigations were carried out following the standard procedures after cross checking for quality control from time to time.

Results

For the first time, out of total 27 cases studied, we have encountered nine cases of heterozygous Hb E trait (33.3%), two members (7.4%) with Hb E-β-thalassemia (double heterozygosity), two cases (7.4%) of sickle cell-Hb E disease (double heterozygosity), two β-thalassemia traits (7.4%), three sickle cell traits (11.1%), 9 normal (33.3%), and none with homozygous Hb E disease. Cases of Hb E trait, Hb E-β-thalassemia, and sickle cell-E disease showed moderate to severe anemia, and target cells, and reduced values of red cell indices like red blood cell count, Hb level, hematocrit, mean cell volume, mean cell Hb and mean cell Hb cencentration, describing abnormal hematological profile and clinical manifestations before blood transfusion.

Conclusions

Double heterozygosity of β-thalassemia with Hb S and Hb E is a rare entity, but occurs with severe clinical manifestations, testifying either migrations and/or genetic admixture. Co-occurrence of Hb E/β-thalassemia in different districts indicates that these anomalies along with other hemoglobinopathies are wide spread in Madhya Pradesh and posing a major genetic burden on vulnerable people of central India.

Prevalence and molecular characterization of structural hemoglobin variants in the Dongguan region of Guangdong province, southern China

The aim of the present study was to find the most prevalent structural hemoglobin (Hb) variants in southern China and to present hematological and molecular data of abnormal Hbs in the population from southern China. The type and frequency of structural Hb variants and their hematological and molecular characteristics were identified in 131 individuals from 30,848 unrelated partners who were referred to the prenatal clinic of Dongguan Maternal & Children Health Hospital, Dongguan, Guangdong, People's Republic of China (PRC) from 2011 to 2013. α-Globin or β-globin chain variants were screened using a capillary electrophoresis (CE) system, and α-globin or β-globin gene mutations were confirmed using sequencing techniques. The gene frequency of Hb variants was 0.4% (131/30,848). The most common α-globin variants were Hb Constant Spring (Hb CS, HBA2: c.427T > C) (0.2%), followed by Hb Q-Thailand (HBA1: c.223G > C) and Hb G-Honolulu (HBA2: c.91G > C). The most common β-globin variant was Hb E (HBB: c.79G > A) (0.09%), followed by Hb New York (HBB: c.341T > A). Our results provide a detailed prevalence and molecular characterization of abnormal Hbs in the population of the Dongguan region. These findings have important implications for a region with a high frequency of α- and β-thalassemias.

Intravascular hemolysis, vascular endothelial cell activation and thrombophilia in splenectomized patients with hemoglobin E/β-thalassemia disease

The relationship between asplenia and thrombophilia in β-thalassemia disease patients is not yet completely understood. One hundred and ten adult hemoglobin (Hb) E/β-thalassemia (E/β-Thal) disease outpatients, dichotomized according to the presence or absence of the spleen, were prospectively studied for evidence of intravascular hemolysis (IVH) and vascular endothelial cell (EC) activation. Biomarkers of IVH (serum cell-free Hb), EC [soluble E-selectin (sE-selectin) and soluble vascular cell adhesion molecule 1 (sVCAM-1)], platelet and EC [soluble P-selectin (sP-selectin)], inflammation [high-sensitivity C-reactive protein (hs-CRP)], and coagulation [thrombin-antithrombin complexes (TAT)] activation, as well as other selected blood tests were determined. The 61 splenectomized patients had a more severe hemolytic disease and higher levels of cell-free Hb and ferritin (p = 0.003), sE-selectin, sP-selectin, hs-CRP, and TAT (p < 0.05). However, serum levels of sVCAM-1 were not different between the two groups. The findings suggested IVH and EC activation. Together with chronic iron overload and chronic low-grade inflammation activation, the findings extend our understanding of the mechanism of thrombophilia in splenectomized E/β-Thal disease patients.

A Rare Case of Hemoglobin E Hemoglobinopathy with Gaucher's Disease

Hemoglobin (Hb) E mutation is common in north-east part of our country. The natural history of Hb E thalassemia is highly variable. The phenotype, for patients with similar mutations, can range from asymptomatic to transfusion dependent. Our patient presented at 2 years of age with failure to thrive and hepatosplenomegaly. Routine work up revealed microcytic, hypochromic red blood cells. Hb E homozygous was indicated on electrophoresis and hemoglobin HPLC. Evaluation of parents revealed Haemoglobin E trait in both. Therapeutic splenectomy revealed Gaucher-like cells. β-Glucocerebrosidase levels were low. Presence of Gaucher-like cells with normal β-glucocerebrosidase (pseudo-Gaucher cells) are known in leukemia, multiple myeloma, thalassemia and mycobacterial infections. Co-existence of Gaucher's disease with Hb E mutation is not reported to the best of our knowledge.

Phenotypic effect of α-globin gene numbers on Indian sickle β-thalassemia patients

BACKGROUND

Sickle cell β-thalassemia is a compound heterozygous state of β-thalassemia and sickle cell anemia. Patient with these conditions showed mild-to-severe clinical phenotype.

OBJECTIVES

The objective of this study was to evaluate the effects of α-globin gene numbers on the phenotype of sickle cell β-thalassemia patients.

MATERIALS AND METHODS

Seventy-five sickle cell β-thalassemia patients were characterized. Clinical, hematological, and molecular characterization was performed in all subjects. Amplified refectory mutation system-polymerase chain reaction was applied for β-thalassemia mutation study while α-genotyping was conducted by Gap-PCR.

RESULTS

Highest frequency of IVS1-5 (33 out of 75 patients) β-thalassemia genotype was recorded. Twenty-eight patients were reported with α-globin chain deletion while four had α-triplications (Anti α-3.7kb). Sickle β-thalassemia patients with α-chain deletions ameliorate hematological and clinical variables.

CONCLUSIONS

This study indicates that the coexistence of α-globin chain deletions showed mild phenotype instead of absence of α-chain deletions while the patients with triplication of α-genes express severe phenotype.

Clinico-haematological Profile of HbE Syndrome in Adults and Children

Haemoglobin E beta thalassemia (HbE beta thalassemia) has a remarkable variability in clinical expression ranging from a mild form of thalassemia intermedia to a transfusion dependent condition. An overlap between the mild variety of HbE beta thalassemia and homozygous HbE disease is common, however, differentiation is required for early institution of therapy and for predicting the later clinical course. Fifty cases of Hb E syndrome comprising of 43 cases of Hb E beta thalassemia and 7 cases of homozygous HbE disease were studied. Their clinico- haematological features and results of high performance liquid chromatography (HPLC) were analysed.

Protection against oxidative stress in beta thalassemia/hemoglobin E erythrocytes by inhibitors of glutathione efflux transporters

In beta thalassemia/hemoglobin E (Hb E), abnormally high levels of oxidative stress account for accelerated senescence and increased destruction of erythrocytes. The present study aimed to investigate the role of glutathione efflux transporters, namely cystic fibrosis transmembrane conductance regulator (CFTR) and multidrug resistance-associated protein 1 (MRP1), in the control of glutathione levels and protection against oxidative challenges in beta thalassemia/Hb E erythrocytes. We found that CFTR protein was expressed in the erythrocytes of beta thalassemia/Hb E patients. Treatments with GlyH-101 (50 µM), a small molecule CFTR inhibitor, and MK571 (50 µM), an MRP1 inhibitor, reduced H₂O₂-induced free radical generation in the erythrocytes by ∼80% and 50%, respectively. Furthermore, combined treatment with GlyH-101 and MK571 completely abolished the induction of reactive oxygen radicals. Increased oxidative stress in the erythrocytes following H₂O₂ challenges was accompanied by a decrease in intracellular level of reduced glutathione (GSH), which was prevented by treatments with GlyH-101 and MK571. CMFDA-based assays revealed that GlyH-101 and MK571 reduced H₂O₂-induced glutathione efflux from the erythrocytes by 87% and 66%, respectively. Interestingly, H₂O₂-induced osmotic tolerance of erythrocytes, a sign of erythrocyte aging, was ameliorated by treatment with GlyH-101. Our study indicates that oxidative stress induces glutathione efflux via CFTR and MRP1 in beta thalassemia/Hb E erythrocytes. Pharmacological inhibition of glutathione efflux represents a potential therapy to delay aging and premature destruction of erythrocytes in beta thalassemia/Hb E.

Protein antioxidants in thalassemia

It is common knowledge that thalassemic patients are under significant oxidative stress. Chronic hemolysis, frequent blood transfusion, and increased intestinal absorption of iron are the main factors that result in iron overload with its subsequent pathophysiologic complications. Iron overload frequently associates with the generation of redox-reactive labile iron, which in turn promotes the production of other reactive oxygen species (ROS). If not neutralized, uncontrolled production of ROS often leads to damage of various intra- and extracellular components such as DNA, proteins, lipids, and small antioxidant molecules among others. A number of endogenous and exogenous defense mechanisms can neutralize and counteract the damaging effects of labile iron and the reactive substances associated with it. Endogenous antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and ferroxidase, may directly or sequentially terminate the activities of ROS. Nonenzymatic endogenous defense mechanisms include metal binding proteins (ceruloplasmin, haptoglobin, albumin, and others) and endogenously produced free radical scavengers (glutathione (GSH), ubiquinols, and uric acid). Exogenous agents that are known to function as antioxidants (vitamins C and E, selenium, and zinc) are mostly diet-derived. In this review, we explore recent findings related to various antioxidative mechanisms operative in thalassemic patients with special emphasis on protein antioxidants.

Association of xmn I polymorphism and hemoglobin e haplotypes on postnatal gamma globin gene expression in homozygous hemoglobin e

Background and Objectives. To explore the role of cis-regulatory sequences within the β globin gene cluster at chromosome 11 on human γ globin gene expression related to Hb E allele, we analyze baseline hematological data and Hb F values together with β globin haplotypes in homozygous Hb E. Patients and Methods. 80 individuals with molecularly confirmed homozygous Hb E were analyzed for the β globin haplotypes and Xmn I polymorphism using PCR-RFLPs. 74 individuals with complete laboratory data were further studied for association analyses. Results. Eight different β globin haplotypes were found linked to Hb E alleles; three major haplotypes were (a) (III), (b) (V), and (c) (IV) accounting for 94% of Hb E chromosomes. A new haplotype (Th-1) was identified and most likely converted from the major ones. The majority of individuals had Hb F < 5%; only 10.8% of homozygous Hb E had high Hb F (average 10.5%, range 5.8–14.3%). No association was found on a specific haplotype or Xmn I in these individuals with high Hb F, measured by alkaline denaturation. Conclusion. The cis-regulation of γ globin gene expression might not be apparent under a milder condition with lesser globin imbalance such as homozygous Hb E.

Increased oxidative metabolism is associated with erythroid precursor expansion in β0-thalassaemia/Hb E disease

Erythropoiesis in β0-thalassaemia/Hb E patients, the most common variant form of β-thalassaemia in Southeast Asia, is characterized by accelerated differentiation and over-expansion of erythroid precursor cells. The mechanism driving this accelerated expansion and differentiation remain unknown. To address this issue a proteomic analysis was undertaken to firstly identify proteins differentially expressed during erythroblast differentiation and a second analysis was undertaken to identify proteins differentially expressed between β0-thalassaemia/Hb E erythroblasts and control erythroblasts. The majority of proteins identified as being differentially expressed between β0-thalassaemia/Hb E and control erythroblasts were constituents of the glycolysis/TCA pathway and levels of oxidative stress correlated with the degree of erythroid expansion. A model was constructed linking these observations with previous studies showing increased phosphorylation of ERK1/2 in thalassemic erythroblasts which predicted the increased activation of PKA, PKB and PKC which Western analysis confirmed. Inhibition of PKA or PKC reduced β0-thalassaemia/Hb E erythroblast differentiation and/or expansion. We propose that increased expansion and differentiation of β0-thalassaemia/Hb E erythroblasts occur as a result of feedback loops acting through increased oxidative metabolism.

Pharmacokinetics of deferiprone in patients with β-thalassaemia: impact of splenectomy and iron status

BACKGROUND AND OBJECTIVE

Iron-rich transfusions and/or a compensatory increase in iron absorption ultimately result in iron loading in patients with β-thalassaemia. Hence, without iron chelation, iron accumulates relentlessly. Deferiprone has been shown to be capable of reducing the iron burden in patients with β-thalassaemia. However, there is wide interpatient variation in deferiprone-induced urinary iron excretion (UIE). We hypothesized that splenectomy and iron status might influence the pharmacokinetic profiles of deferiprone in patients with β-thalassaemia/haemoglobin E, and the present study was aimed at examining this hypothesis.

STUDY PARTICIPANTS AND METHODS

Thirty-one patients with β-thalassaemia/haemoglobin E (20 splenectomized and 11 non-splenectomized patients) were enrolled in the study. After an overnight fast, the subjects received a single oral dose of deferiprone 25 mg/kg of bodyweight. Blood samples were collected pre-dosing and at 15, 30, 45, 60, 90, 120, 180, 240, 300, 360 and 480 minutes after dosing. Urine output was pooled and collected at 0-2, 2-4, 4-8, 8-12 and 12-24 hour intervals. Serum and urine concentrations of deferiprone and its metabolite deferiprone glucuronide were determined using a validated high-performance liquid chromatography method. Serum deferiprone-chelated iron and UIE were determined using a validated colourimetric method.

RESULTS

No significant difference in the pharmacokinetic parameters of non-conjugated deferiprone was observed between splenectomized and non-splenectomized patients. However, the maximum serum concentration (C(max)) and the area under the serum concentration-time curve (AUC) from time zero to infinity (AUC(∞)) values of deferiprone glucuronide were significantly lower (both p < 0.05) in splenectomized patients (median 53.2 μmol/L and 12 634 μmol • min/L, respectively) than in non-splenectomized patients (median 70.5 μmol/L and 20 601 μmol • min/L, respectively). The C(max) and the AUC from time zero to the time of the last measurable concentration (AUC(last)) values of serum deferiprone-chelated iron, as well as UIE, were significantly higher (p < 0.001) in splenectomized patients (median values 7.1 μmol/L, 1645 μmol • min/L and 77.1 μmol, respectively) than in non-splenectomized patients (median values 3.1 μmol/L, 545 μmol • min/L and 12.5 μmol, respectively). Urinary excretion of non-conjugated deferiprone and deferiprone glucuronide did not differ between the two groups. Further analyses using multiple linear regressions indicated that the iron profiles (non-transferrin-bound iron and ferritin) were significant predictors of the pharmacokinetic parameters of non-conjugated deferiprone, deferiprone-chelated iron and UIE. In addition, splenectomy status was identified as the strongest predictor of the AUC(last) of deferiprone-chelated iron and UIE.

CONCLUSION

Both iron and splenectomy status have significant effects on the pharmacokinetics and iron chelation efficacy of deferiprone. A greater degree of iron overload in splenectomized patients results in alterations in pharmacokinetic parameters (the C(max) and AUC) of deferiprone glucuronide and deferiprone-chelated iron, as well as a significant increase in UIE.