Beta-thalassemia

Population Screening for Hemoglobinopathies

Hemoglobinopathies are the most common single-gene disorders in the world. Their prevalence is predicted to increase in the future, and low-income hemoglobinopathy-endemic regions need to manage most of the world's affected persons. International organizations, governments, and other stakeholders have initiated national or regional prevention programs in both endemic and nonendemic countries by performing population screening for α- and β-thalassemia, HbE disease, and sickle cell disease in neonates, adolescents, reproductive-age adults (preconceptionally or in the early antenatal period), and family members of diagnosed cases. The main aim of screening is to reduce the number of affected births and, in the case of sickle cell disease, reduce childhood morbidity and mortality. Screening strategies vary depending on the population group, but a few common screening test methods are universally used. We discuss the salient features of population-screening programs around the globe as well as current and proposed screening test methodologies.

An APOBEC3A-Cas9 base editor with minimized bystander and off-target activities

Base editor (BE) technology, which uses CRISPR-Cas9 to direct cytidine deaminase enzymatic activity to specific genomic loci, enables the highly efficient introduction of precise cytidine-to-thymidine DNA alterations^1–6. However, existing BEs create unwanted C to T alterations when more than one C is present in the enzyme’s five-base-pair editing window. Here we describe a strategy for reducing bystander mutations using an engineered human APOBEC3A (eA3A) domain, which preferentially deaminates cytidines in specific motifs according to a TCR>TCY>VCN hierarchy. In direct comparisons with the widely used BE3 fusion in human cells, our eA3A-BE3 fusion exhibits similar activities on cytidines in TC motifs but greatly reduced editing on cytidines in other sequence contexts. eA3A-BE3 corrects a human beta-thalassemia promoter mutation with much higher (>40-fold) precision than BE3. We also demonstrate that eA3A-BE3 shows reduced mutation frequencies on known off-target sites of BE3, even when targeting promiscuous homopolymeric sites.

Efficacy and safety of resveratrol, an oral hemoglobin F-augmenting agent, in patients with beta-thalassemia intermedia

Recently, resveratrol showed induction of γ-globin mRNA synthesis in human erythroid precursors and reducing oxidative stress in red cells of thalassemia patients in many in vitro studies. We aimed to investigate the efficacy and safety of resveratrol, for the first time, in non-transfusion-dependent beta-thalassemia intermedia (B-TI) in Southern Iran. In this double-blind randomized clinical trial, 54 patients with B-TI were investigated during 6 months between October 2016 and March 2017. Patients were randomly allocated into three groups by simple randomization method. Group 1 (hydroxyurea (HU) and placebo, 18 patients), group 2 (resveratrol/piperine and placebo, 16 patients), and group 3(HU and resveratrol/piperine, 20 patients). Primary end point was considered as change in hemoglobin (Hb) levels and need for blood transfusion. Drug safety was considered as a secondary end point. Mean age of the patients was 28.2 ± 5.6 (18-42) years. Response rate was not significantly different among the three groups (P > 0.05). Higher percentages of adverse events were detected in groups 2 (31.3%) and 3 (25%) compared to group 1 (5.6%). However, the difference was not statistically significant (P > 0.05). All reported adverse events were gastrointestinal symptoms. Resveratrol showed a similar efficacy with HU in the small population of non-transfusion B-TI patients during a 6-month follow-up. Complications, mostly gastrointestinal, were observed more frequently in resveratrol groups compared to the HU group. Although it was not statistically significant, more attention should be given to safety and efficacy of resveratrol as an oral HbF-augmenting agent.

An investigation of the effects of curcumin on iron overload, hepcidin level, and liver function in β-thalassemia major patients: A double-blind randomized controlled clinical trial

This study investigated the effects of curcumin, the active polyphenol in turmeric, on iron overload, hepcidin level, and liver function in β-thalassemia major patients. This double-blind randomized controlled clinical trial was conducted on 68 β-thalassemia major patients. The subjects were randomly divided into 2 groups to receive either 500 mg curcumin capsules (total: 1,000 mg) twice daily or placebo for 12 weeks. Dietary intakes and biochemical variables including hemoglobin, transferrin saturation, total iron binding capacity, nontransferrin bound iron (NTBI), ferritin, hepcidin, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were assessed at the beginning and end of the trial. Curcumin significantly reduced serum levels of NTBI (2.83 ± 1.08 compared with 2.22 ± 0.97 μmol/L, p = .001), ALT (42.86 ± 11.15 compared with 40.60 ± 9.89 U/L, p = .018), and AST (49.45 ± 12.39 compared with 46.30 ± 10.85 U/L, p = .002) at the end of the study. Based on analysis of covariance, a significant decrease was also observed in levels of NTBI (2.22 ± 0.97 vs. 2.55 ± 0.94 μmol/L, p = .026), ALT (40.60 ± 9.89 vs. 45.01 ± 10.42 U/L, p = .004), and AST (46.30 ± 10.85 vs. 50.99 ± 9.36 U/L, p = .009) in curcumin group in comparison with placebo group. There were no significant changes in hepcidin and other variables in any of the 2 groups. Curcumin administration alleviated iron burden and liver dysfunction by reducing NTBI, ALT, and AST levels in patients with β-thalassemia major.

Trichothiodystrophy causative TFIIEβ mutation affects transcription in highly differentiated tissue

The rare recessive developmental disorder Trichothiodystrophy (TTD) is characterized by brittle hair and nails. Patients also present a variable set of poorly explained additional clinical features, including ichthyosis, impaired intelligence, developmental delay and anemia. About half of TTD patients are photosensitive due to inherited defects in the DNA repair and transcription factor II H (TFIIH). The pathophysiological contributions of unrepaired DNA lesions and impaired transcription have not been dissected yet. Here, we functionally characterize the consequence of a homozygous missense mutation in the general transcription factor II E, subunit 2 (GTF2E2/TFIIEβ) of two unrelated non-photosensitive TTD (NPS-TTD) families. We demonstrate that mutant TFIIEβ strongly reduces the total amount of the entire TFIIE complex, with a remarkable temperature-sensitive transcription defect, which strikingly correlates with the phenotypic aggravation of key clinical symptoms after episodes of high fever. We performed induced pluripotent stem (iPS) cell reprogramming of patient fibroblasts followed by in vitro erythroid differentiation to translate the intriguing molecular defect to phenotypic expression in relevant tissue, to disclose the molecular basis for some specific TTD features. We observed a clear hematopoietic defect during late-stage differentiation associated with hemoglobin subunit imbalance. These new findings of a DNA repair-independent transcription defect and tissue-specific malfunctioning provide novel mechanistic insight into the etiology of TTD.

Clinical application of a protocol based on universal next-generation sequencing for the diagnosis of beta-thalassaemia and sickle cell anaemia in preimplantation embryos

RESEARCH QUESTION

Mutations of the beta-globin gene (HBB) cause beta-thalassaemia and sickle cell anaemia. These are the most common cause of severe inherited disease in humans. Traditional preimplantation genetic testing protocols for detecting HBB mutations frequently involve labour intensive, patient-specific test designs owing to the wide diversity of disease-associated HBB mutations. We, therefore, asked the question whether a universally applicable preimplantation genetic testing method can be developed to test for HBB gene mutations.

DESIGN

A multiplex polymerase chain reaction protocol was designed, allowing simultaneous amplification of multiple overlapping DNA fragments encompassing the entire HBB gene sequence in addition to 17 characterized, closely linked single nucleotide polymorphisms (SNP). Amplicons were then analysed using a next-generation sequencing method, revealing mutations and SNP genotypes. The protocol was extensively validated, optimized and eventually clinically applied on whole-genome amplified DNA derived from embryos of three couples carrying different combinations of beta-thalassaemia mutations.

RESULTS

The HBB mutation status and associated SNP haplotypes were successfully determined in all 21 embryos. Analysis of 141 heterozygous sites showed no instances of allele dropout and the test displayed 100% concordance compared with the results obtained from karyomapping. This suggests that the combination of trophectoderm biopsy and highly sensitive next-generation sequencing may provide superior accuracy than typically achieved using traditional preimplantation genetic testing methods. Importantly, no patient-specific test design or optimization was needed.

CONCLUSIONS

It is hoped that protocols that deliver almost universally applicable low-cost tests, without compromising diagnostic accuracy, will improve patient access to preimplantation genetic testing, especially in less affluent parts of the world.

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.

Identifying β-thalassemia carriers using a data mining approach: The case of the Gaza Strip, Palestine

Thalassemia is considered one of the most common genetic blood disorders that has received excessive attention in the medical research fields worldwide. Under this context, one of the greatest challenges for healthcare professionals is to correctly differentiate normal individuals from asymptomatic thalassemia carriers. Usually, thalassemia diagnosis is based on certain measurable characteristic changes to blood cell counts and related indices. These characteristic changes can be derived easily when performing a complete blood count test (CBC) using a special fully automated blood analyzer or counter. However, the reliability of the CBC test alone is questionable with possible candidate characteristics that could be seen in other disorders, leading to misdiagnosis of thalassemia. Therefore, other costly and time-consuming tests should be performed that may cause serious consequences due to the delay in the correct diagnosis. To help overcoming these challenging diagnostic issues, this work presents a new novel dataset collected from Palestine Avenir Foundation for persons tested for thalassemia. We aim to compile a gold standard dataset for thalassemia and make it available for researchers in this field. Moreover, we use this dataset to predict the specific type of thalassemia known as beta thalassemia (β-thalassemia) based on hybrid data mining model. The proposed model consists of two main steps. First, to overcome the problem of the highly imbalanced class distribution in the dataset, a balancing technique called SMOTE is proposed and applied to handle this problem. In the second step, four classification models, namely k-nearest neighbors (k-NN), naïve Bayesian (NB), decision tree (DT) and the multilayer perceptron (MLP) neural network are used to differentiate between normal persons and those patients carrying β-thalassemia. Different evaluation metrics are used to assess the performance of the proposed model. The experimental results show that the SMOTE oversampling method can effectively improve the identification ratio of β-thalassemia carriers in a highly imbalanced class distribution. The results reveal also that the NB classifier achieved the best performance in differentiating between normal and β-thalassemia carriers at oversampling SMOTE ratio of 400%. This combination shows a specificity of 99.47% and a sensitivity of 98.81%.

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.

Cationic Polymer-Mediated CRISPR/Cas9 Plasmid Delivery for Genome Editing

Delivery of CRISPR (clustered regularly interspaced short palindromic repeats)/CRISPR-associated protein-9 (Cas9) represents a major hurdle for successful clinical translation of genome editing tools. Owing to the large size of plasmids that encode Cas9 and single-guide RNA (sgRNA), genome editing efficiency mediated by current delivery carriers is still unsatisfactory to meet the requirement for its real applications. Herein, cationic polymer polyethyleneimine-β-cyclodextrin (PC), known to be efficient for small plasmid transfection, is reported to likewise mediate efficient delivery of plasmid encoding Cas9 and sgRNA. Whereas PC can condense and encapsulate large plasmids at high N/P ratio, the delivery of plasmid results in efficient editing at two genome loci, namely, hemoglobin subunit beta (19.1%) and rhomboid 5 homolog 1 (RHBDF1) (7.0%). Sanger sequencing further confirms the successful genome editing at these loci. This study defines a new strategy for the delivery of the large plasmid encoding Cas9/sgRNA for efficient genome editing.

Gene Therapy in Patients with Transfusion-Dependent β-Thalassemia

BACKGROUND

Donor availability and transplantation-related risks limit the broad use of allogeneic hematopoietic-cell transplantation in patients with transfusion-dependent β-thalassemia. After previously establishing that lentiviral transfer of a marked β-globin (β^A-T87Q) gene could substitute for long-term red-cell transfusions in a patient with β-thalassemia, we wanted to evaluate the safety and efficacy of such gene therapy in patients with transfusion-dependent β-thalassemia.

METHODS

In two phase 1-2 studies, we obtained mobilized autologous CD34+ cells from 22 patients (12 to 35 years of age) with transfusion-dependent β-thalassemia and transduced the cells ex vivo with LentiGlobin BB305 vector, which encodes adult hemoglobin (HbA) with a T87Q amino acid substitution (HbA^T87Q). The cells were then reinfused after the patients had undergone myeloablative busulfan conditioning. We subsequently monitored adverse events, vector integration, and levels of replication-competent lentivirus. Efficacy assessments included levels of total hemoglobin and HbA^T87Q, transfusion requirements, and average vector copy number.

RESULTS

At a median of 26 months (range, 15 to 42) after infusion of the gene-modified cells, all but 1 of the 13 patients who had a non-β⁰/β⁰ genotype had stopped receiving red-cell transfusions; the levels of HbA^T87Q ranged from 3.4 to 10.0 g per deciliter, and the levels of total hemoglobin ranged from 8.2 to 13.7 g per deciliter. Correction of biologic markers of dyserythropoiesis was achieved in evaluated patients with hemoglobin levels near normal ranges. In 9 patients with a β⁰/β⁰ genotype or two copies of the IVS1-110 mutation, the median annualized transfusion volume was decreased by 73%, and red-cell transfusions were discontinued in 3 patients. Treatment-related adverse events were typical of those associated with autologous stem-cell transplantation. No clonal dominance related to vector integration was observed.

CONCLUSIONS

Gene therapy with autologous CD34+ cells transduced with the BB305 vector reduced or eliminated the need for long-term red-cell transfusions in 22 patients with severe β-thalassemia without serious adverse events related to the drug product. (Funded by Bluebird Bio and others; HGB-204 and HGB-205 ClinicalTrials.gov numbers, NCT01745120 and NCT02151526 .).

Extracellular Electron Transfer Powers Enterococcus faecalis Biofilm Metabolism

Enterococci are important human commensals and significant opportunistic pathogens. Biofilm-related enterococcal infections, such as endocarditis, urinary tract infections, wound and surgical site infections, and medical device-associated infections, often become chronic upon the formation of biofilm. The biofilm matrix establishes properties that distinguish this state from free-living bacterial cells and increase tolerance to antimicrobial interventions. The metabolic versatility of the enterococci is reflected in the diversity and complexity of environments and communities in which they thrive. Understanding metabolic factors governing colonization and persistence in different host niches can reveal factors influencing the transition to biofilm pathogenicity. Here, we report a form of iron-dependent metabolism for Enterococcus faecalis where, in the absence of heme, extracellular electron transfer (EET) and increased ATP production augment biofilm growth. We observe alterations in biofilm matrix depth and composition during iron-augmented biofilm growth. We show that the ldh gene encoding l-lactate dehydrogenase is required for iron-augmented energy production and biofilm formation and promotes EET.

Bacterial metabolic versatility can often influence the outcome of host-pathogen interactions, yet causes of metabolic shifts are difficult to resolve. The bacterial biofilm matrix provides the structural and functional support that distinguishes this state from free-living bacterial cells. Here, we show that the biofilm matrix can immobilize iron, providing access to this growth-promoting resource which is otherwise inaccessible in the planktonic state. Our data show that in the absence of heme, Enterococcus faecalisl-lactate dehydrogenase promotes EET and uses matrix-associated iron to carry out EET. Therefore, the presence of iron within the biofilm matrix leads to enhanced biofilm growth.

Partial Splenectomy in the treatment of an adult with β thalassemia intermedia: A case report

Introduction

Thalassemia is a common disease which treatment is often based on splenectomy. The risks associated with total splenectomy stimulated partial splenectomy as a potentially alternative therapy.

Case presentation

A 45 year-old female patient with long term follow-up for β thalassemia intermedia started to develop signs of hypersplenism and iron overload. A partial splenectomy was performed and was observed a marked hematologic improvement while preserving the desired splenic function.

Discussion

Partial splenectomy proved to provide a persistent decrease in hemolytic rate while preserving the integrity of splenic phagocytic function, presenting itself as an effective alternative to total splenectomy. After being subjected to partial splenectomy, our patient experienced a sustained control of hemolysis and showed no signs of hypersplenism or iron overload. No splenic regrowth or infectious complications were observed. The major drawbacks of partial splenectomy are the increased risk of intra- and postoperative bleeding, splenic remnant torsion and splenic regrowth.

Conclusion

Partial splenectomy is an alternative to total splenectomy for the treatment of adult β Thalassemia intermedia patients avoiding the risks associated with total splenectomy.

Genotype-phenotype Correlation of β-Thalassemia in Croatian Patients: A Specific HBB Gene Mutations

An analysis of genotype-phenotype correlation was performed for 14 patients with beta-thalassemia who had been registered in Referral Centre for hematology and oncology of the University Hospital Centre, Zagreb, Croatia. HBB gene mutations were determined using a gene-specific Q5 High-Fidelity PCR analysis with direct DNA sequencing of amplified transcripts. Mahidol score index used for classification of thalassemia severity was found to be low for all the patients enrolled in the study, indicating a mild β-thalassemia phenotype with no signs of disease progression. Most of the patients have already described gene mutations: IVS-II-666 C>T (HBB:c.316-185C>T) and IVS-II-16 G>C (HBB:c.315+16G>C). Each of the aforementioned mutations was found in (11/14; 78,57%) and (10/14; 71,43%) of our patients, respectively. Recently published HBB:c.9T>C mutation was found in 8 of 14 (57,14%) in our study group. IVSII-74 T>G (HBB:c.315+74T>G) is a worldwide mutation found in 6 of 14 (42.86%) of our patients. All these mutations occur among Croatian children with no obvious Indian/Near Eastern/Iranian ancestry. We also identified 7 de novo mutations (c.316-135het_dupT, c.316-133A>G, c.93-54G>A, c.316-68_316-67het_insCGG, c.316-342delA, c.316-312delT, c.316-209delT) of mild severity phenotype according to Mahidol classification score index. We did not find children or adults with thalassemia major severity phenotype.

Analysis of Common β-Thalassemia Mutations in North Vietnam

Available and flexible choice of methods for screening and detecting β-thalassemia (β-thal) can promote control of thalassemia in developing countries. In this study, two methods, the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and reverse dot-blot hybridization assays were developed to detect common β-thal mutations in 244 thalassemia patients and 152 healthy people in North Vietnam. The most common mutation was codon 26 (G>A), also known as Hb E (HBB: c.79G>A), accounting for 26.4% of the total studied chromosomes, followed by codons 41/42 (-TCTT) (HBB: c.126_129delCTTT) and codon 17 (A>T) (HBB: c.c.52A>T), accounting for 19.4 and 16.4%, respectively. In addition, codon 95 (+A) (HBB: c.c.287_288insA) that is known as the Vietnamese mutation, accounted for 0.6%. Moreover, the heterozygous state of the four mutations was also found in healthy people, of which Hb E was again the most common mutation with a frequency 3.0%. The results of this study provide available methods and indicative data for preventive and control strategies concerning the genetic diagnosis of thalassemia.

One-step genetic correction of hemoglobin E/beta-thalassemia patient-derived iPSCs by the CRISPR/Cas9 system

Background

Thalassemia is the most common genetic disease worldwide; those with severe disease require lifelong blood transfusion and iron chelation therapy. The definitive cure for thalassemia is allogeneic hematopoietic stem cell transplantation, which is limited due to lack of HLA-matched donors and the risk of post-transplant complications. Induced pluripotent stem cell (iPSC) technology offers prospects for autologous cell-based therapy which could avoid the immunological problems. We now report genetic correction of the beta hemoglobin (HBB) gene in iPSCs derived from a patient with a double heterozygote for hemoglobin E and β-thalassemia (HbE/β-thalassemia), the most common thalassemia syndrome in Thailand and Southeast Asia.

Methods

We used the CRISPR/Cas9 system to target the hemoglobin E mutation from one allele of the HBB gene by homology-directed repair with a single-stranded DNA oligonucleotide template. DNA sequences of the corrected iPSCs were validated by Sanger sequencing. The corrected clones were differentiated into hematopoietic progenitor and erythroid cells to confirm their multilineage differentiation potential and hemoglobin expression.

Results

The hemoglobin E mutation of HbE/β-thalassemia iPSCs was seamlessly corrected by the CRISPR/Cas9 system. The corrected clones were differentiated into hematopoietic progenitor cells under feeder-free and OP9 coculture systems. These progenitor cells were further expanded in erythroid liquid culture system and developed into erythroid cells that expressed mature HBB gene and HBB protein.

Conclusions

Our study provides a strategy to correct hemoglobin E mutation in one step and these corrected iPSCs can be differentiated into hematopoietic stem cells to be used for autologous transplantation in patients with HbE/β-thalassemia in the future.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0779-3) contains supplementary material, which is available to authorized users.

Quality of life among adolescents aged 14 to 18 years with Beta-Thalassemia Major (TM) in Qatar

BACKGROUND

Thalassemia  is a heterogeneous group of inherited disorders of hemoglobin synthesis. It is a common disease in Mediterranean, Southeast Asia, Indian subcontinent, and Middle East countries, including Qatar.

PURPOSE

The aim of this study was to assess the quality of life (QOL) among patients aged 14 to 18 years with thalassemia major (TM) in Qatar and correlates their QOL with bio-demographic data of the patients compared to healthy controls.

MATERIALS AND METHODS

This cross-sectional study measured the QOL in adolescents with thalassemia major who were attending ambulatory units in a tertiary hospital in Qatar. Forty children and adolescents with TM and 40 healthy participants were enrolled in the study. Forty-two (52.5%) participants were males and 38 (47.5%) females. Data were collected utilizing PedsQLTM 4.0 generic core scale and were analyzed using the appropriate statistical method.

RESULTS

Children with TM had significantly lower and more variable overall quality of life score (69.1 ± 16.8) compared to healthy matched children (77 ± 12.8), (p <0.001). Both groups were not different from the physical, emotional, and social domains. Thalassemic  adolescents had also a significantly lower school performance.

CONCLUSIONS

TM adversely affects the QOL of children and adolescents and this necessitates applying more efforts to help them improve and achieve a desirable quality of life. Patients with TM need more attention in schools that can be accomplished by implementing a special program for their management that needs a mutual collaboration between Ministry of Public Health (MoPH) and Ministry of Education (MoE) in Qatar.

Polyneuropathy and myopathy in beta-thalassemia major patients

The thalassemias are the most common single gene disorder in the world. Nowadays, the average life expectancy of patients in developed countries has increased significantly, while, there was an increase of complications. We aimed to investigate peripheral neuropathy and myopathy in this patient group using a neurophysiological study. We performed nerve conduction studies and electromyography of upper and lower extremities on 36 beta-thalassemia major (β-thal) patients. The electrophysiological findings were correlated with demographic data and laboratory parameters of the disease. Patients with β-thal present polyneuropathy or myopathy at (50%). Polyneuropathy was detected in (38.9%) and myopathy in (27.8%), while polyneuropathy and myopathy were present at (16.7%) with an overlap of the diseases in 1/3 of the patients. There was not a statistically significant correlation of polyneuropathy and myopathy with age, sex, splenectomy, nor with respect to laboratory parameters, hemoglobin, and ferritin. However, there was a statistically significant correlation of polyneuropathy and myopathy with iron overload, as recorded by the magnetic resonance imaging (MRI) of the heart and the liver. Our findings suggest that iron overload plays a key role in the pathogenesis of polyneuropathy and myopathy in β-thal patients, and performing heart and liver MRI for the prediction of such lesions in an annual basis is warranted.

Candidate SNP markers of reproductive potential are predicted by a significant change in the affinity of TATA-binding protein for human gene promoters

BACKGROUND

The progress of medicine, science, technology, education, and culture improves, year by year, quality of life and life expectancy of the populace. The modern human has a chance to further improve the quality and duration of his/her life and the lives of his/her loved ones by bringing their lifestyle in line with their sequenced individual genomes. With this in mind, one of genome-based developments at the junction of personalized medicine and bioinformatics will be considered in this work, where we used two Web services: (i) SNP_TATA_Comparator to search for alleles with a single nucleotide polymorphism (SNP) that alters the affinity of TATA-binding protein (TBP) for the TATA boxes of human gene promoters and (ii) PubMed to look for retrospective clinical reviews on changes in physiological indicators of reproductive potential in carriers of these alleles.

RESULTS

A total of 126 SNP markers of female reproductive potential, capable of altering the affinity of TBP for gene promoters, were found using the two above-mentioned Web services. For example, 10 candidate SNP markers of thrombosis (e.g., rs563763767) can cause overproduction of coagulation inducers. In pregnant women, Hughes syndrome provokes thrombosis with a fatal outcome although this syndrome can be diagnosed and eliminated even at the earliest stages of its development. Thus, in women carrying any of the above SNPs, preventive treatment of this syndrome before a planned pregnancy can reduce the risk of death. Similarly, seven SNP markers predicted here (e.g., rs774688955) can elevate the risk of myocardial infarction. In line with Bowles' lifespan theory, women carrying any of these SNPs may modify their lifestyle to improve their longevity if they can take under advisement that risks of myocardial infarction increase with age of the mother, total number of pregnancies, in multiple pregnancies, pregnancies under the age of 20, hypertension, preeclampsia, menstrual cycle irregularity, and in women smokers.

CONCLUSIONS

According to Bowles' lifespan theory-which links reproductive potential, quality of life, and life expectancy-the above information was compiled for those who would like to reduce risks of diseases corresponding to alleles in own sequenced genomes. Candidate SNP markers can focus the clinical analysis of unannotated SNPs, after which they may become useful for people who would like to bring their lifestyle in line with their sequenced individual genomes.

Characterization of Gene Alterations following Editing of the β-Globin Gene Locus in Hematopoietic Stem/Progenitor Cells

The use of engineered nucleases combined with a homologous DNA donor template can result in targeted gene correction of the sickle cell disease mutation in hematopoietic stem and progenitor cells. However, because of the high homology between the adjacent human β- and δ-globin genes, off-target cleavage is observed at δ-globin when using some endonucleases targeted to the sickle mutation in β-globin. Introduction of multiple double-stranded breaks by endonucleases has the potential to induce intergenic alterations. Using a novel droplet digital PCR assay and high-throughput sequencing, we characterized the frequency of rearrangements between the β- and δ-globin paralogs when delivering these nucleases. Pooled CD34+ cells and colony-forming units from sickle bone marrow were treated with nuclease only or including a donor template and then analyzed for potential gene rearrangements. It was observed that, in pooled CD34+ cells and colony-forming units, the intergenic β-δ-globin deletion was the most frequent rearrangement, followed by inversion of the intergenic fragment, with the inter-chromosomal translocation as the least frequent. No rearrangements were observed when endonuclease activity was restricted to on-target β-globin cleavage. These findings demonstrate the need to develop site-specific endonucleases with high specificity to avoid unwanted gene alterations.

Hsp90 chaperones hemoglobin maturation in erythroid and nonerythroid cells

Maturation of adult (α2β2) and fetal hemoglobin (α2γ2) tetramers requires that heme be incorporated into each globin. While hemoglobin alpha (Hb-α) relies on a specific erythroid chaperone (alpha Hb-stabilizing protein, AHSP), the other chaperones that may help mature the partner globins (Hb-γ or Hb-β) in erythroid cells, or may enable nonerythroid cells to express mature Hb, are unknown. We investigated a role for heat-shock protein 90 (hsp90) in Hb maturation in erythroid precursor cells that naturally express Hb-α with either Hb-γ (K562 and HiDEP-1 cells) or Hb-β (HUDEP-2) and in nonerythroid cell lines that either endogenously express Hb-αβ (RAW and A549) or that we transfected to express the globins. We found the following: (i) AHSP and hsp90 associate with distinct globin partners in their immature heme-free states (AHSP with apo-Hbα, and hsp90 with apo-Hbβ or Hb-γ) and that hsp90 does not associate with mature Hb. (ii) Hsp90 stabilizes the apo-globins and helps to drive their heme insertion reactions, as judged by pharmacologic hsp90 inhibition or by coexpression of an ATP-ase defective hsp90. (iii) In nonerythroid cells, heme insertion into all globins became hsp90-dependent, which may explain how mixed Hb tetramers can mature in cells that do not express AHSP. Together, our findings uncover a process in which hsp90 first binds to immature, heme-free Hb-γ or Hb-β, drives their heme insertion process, and then dissociates to allow their heterotetramer formation with Hb-α. Thus, in driving heme insertion, hsp90 works in concert with AHSP to generate functional Hb tetramers during erythropoiesis.

Association between sickle cell and β-thalassemia genes and hemoglobin concentration and anemia in children and non-pregnant women in Sierra Leone: ancillary analysis of data from Sierra Leone's 2013 National Micronutrient Survey

OBJECTIVE

By measuring the associations between the presence of sickle cell and β-thalassemia genes, we assessed the extent to which these hemoglobinopathies contribute to the high prevalence of anemia observed in preschool-aged children and women of reproductive age in Sierra Leone.

RESULTS

The prevalence of anemia was statistically significantly higher in children with homozygous sickle cell genes (HbSS) than in children with normal hemoglobin genes (HbAA or HbAC), but there was no difference in anemia prevalence in those with heterozygous sickle cell trait (HbAS or HbSC) compared with those with normal hemoglobin genes. In women, there was no difference in anemia prevalence by sickle cell status. In both children and women, there was no difference in the anemia prevalence for individuals with or without the β-thalassemia gene. For both sickle cell and β-thalassemia, there was no significant difference in hemoglobin concentrations by sickle cell or β-thalassemia status. Anemia prevalence was higher in children and women with homozygous sickle cell (HbSS). However, as the prevalence of HbSS children (5.4%) and women (1.6%) was quite small, it is unlikely that these hemoglobinopathies substantially contributed to the high anemia prevalence found in the 2013 national micronutrient survey.

ELECTRORETINOGRAPHIC AND VISUAL-EVOKED POTENTIAL CHANGES IN RELATION TO CHELATION MODALITY IN CHILDREN WITH THALASSEMIA

PURPOSE

To evaluate possible benefits of using electrophysiological investigations for detecting retinal and visual pathway changes and correlating them with chelation modality in children with thalassemia.

METHODS

This study included 60 patients on single oral iron chelator (deferasirox) (Group 1), 60 on deferoxamine chelator (Group 2), and 60 controls (Group 3). Participants underwent full ophthalmologic examination, pattern visual-evoked potential, pattern electroretinogram, and multifocal electroretinogram.

RESULTS

Fundus showed no abnormalities. Multifocal electroretinogram mean P1 amplitude showed statistically significant differences in all 5 rings, amplitudes being significantly lower in Groups 1 and 2 than Group 3; moreover, significantly lower in Group 2 than Group 1. There was a statistically significant difference between groups regarding P50 wave latency and N35-P50 of pattern electroretinogram amplitude (P < 0.001 and P < 0.001, respectively). However, there were no statistically significant differences between groups regarding N95 wave of pattern electroretinogram and pattern visual-evoked potential waves' amplitude and latency. Multiple regression analyses illustrated that chelator was the most important determinant for multifocal electroretinogram and P50 parameters.

CONCLUSION

Preclinical electrophysiologic changes existed in thalassemics, more obvious in those on deferoxamine. Electrophysiologic studies analysis denotes an early toxic macular insult rather than optic nerve affection. Thus, regular follow-up using multifocal electroretinogram and pattern electroretinogram is recommended.

Increased levels of advanced glycation end products positively correlate with iron overload and oxidative stress markers in patients with β-thalassemia major

The impaired biosynthesis of the β-globin chain in β-thalassemia leads to the accumulation of unpaired alpha globin chains, failure in hemoglobin formation, and iron overload due to frequent blood transfusion. Iron excess causes oxidative stress and massive tissue injuries. Advanced glycation end products (AGEs) are harmful agents, and their production accelerates in oxidative conditions. This study was conducted on 45 patients with major β-thalassemia who received frequent blood transfusions and chelation therapy and were compared to 40 healthy subjects. Metabolic parameters including glycemic and iron indices, hepatic and renal functions tests, oxidative stress markers, and AGEs (carboxymethyl-lysine and pentosidine) levels were measured. All parameters were significantly increased in β-thalassemia compared to the control except for glutathione levels. Blood glucose, iron, serum ferritin, non-transferrin-bound iron (NTBI), MDA, soluble form of low-density lipoprotein receptor, glutathione peroxidase, total reactive oxygen species (ROS), and AGE levels were significantly higher in the β-thalassemia patients. Iron and ferritin showed a significant positive correlation with pentosidine (P < 0.01) but not with carboxymethyl-lysine. The NTBI was markedly increased in the β-thalassemia patients, and its levels correlated significantly with both carboxymethyl-lysine and pentosidine (P < 0.05). Our findings confirm the oxidative status generated by the iron overload in β-thalassemia major patients and highlight the enhanced formation of AGEs, which may play an important role in the pathogenesis of β-thalassemia major.

High resolution melting curve analysis targeting the HBB gene mutational hot-spot offers a reliable screening approach for all common as well as most of the rare beta-globin gene mutations in Bangladesh

BACKGROUND

Bangladesh lies in the global thalassemia belt, which has a defined mutational hot-spot in the beta-globin gene. The high carrier frequencies of beta-thalassemia trait and hemoglobin E-trait in Bangladesh necessitate a reliable DNA-based carrier screening approach that could supplement the use of hematological and electrophoretic indices to overcome the barriers of carrier screening. With this view in mind, the study aimed to establish a high resolution melting (HRM) curve-based rapid and reliable mutation screening method targeting the mutational hot-spot of South Asian and Southeast Asian countries that encompasses exon-1 (c.1 - c.92), intron-1 (c.92 + 1 - c.92 + 130) and a portion of exon-2 (c.93 - c.217) of the HBB gene which harbors more than 95% of mutant alleles responsible for beta-thalassemia in Bangladesh.

RESULTS

Our HRM approach could successfully differentiate ten beta-globin gene mutations, namely c.79G > A, c.92 + 5G > C, c.126_129delCTTT, c.27_28insG, c.46delT, c.47G > A, c.92G > C, c.92 + 130G > C, c.126delC and c.135delC in heterozygous states from the wild type alleles, implying the significance of the approach for carrier screening as the first three of these mutations account for ~85% of total mutant alleles in Bangladesh. Moreover, different combinations of compound heterozygous mutations were found to generate melt curves that were distinct from the wild type alleles and from one another. Based on the findings, sixteen reference samples were run in parallel to 41 unknown specimens to perform direct genotyping of the beta-thalassemia specimens using HRM. The HRM-based genotyping of the unknown specimens showed 100% consistency with the sequencing result.

CONCLUSIONS

Targeting the mutational hot-spot, the HRM approach could be successfully applied for screening of beta-thalassemia carriers in Bangladesh as well as in other countries of South Asia and Southeast Asia. The approach could be a useful supplement of hematological and electrophortic indices in order to avoid false positive and false negative results.

Rheumatological complications of beta-thalassaemia: an overview

Beta-thalassaemia, an autosomal recessive haemoglobinopathy, ranks among the most frequent monogenetic diseases globally. The severe form of the disease, beta-thalassaemia major, is accompanied by progressive involvement of multiple organ systems as a result of the disease pathophysiology as well as iron overload from blood transfusions on a regular basis. Some of the manifestations might also be caused by medications used to manage iron overload. The purpose of this review is to highlight the rheumatological complications of beta-thalassaemia, which include musculoskeletal manifestations, such as arthritis and arthropathies, joint effusions, osteoporosis, bone fractures and myalgias, in addition to CTDs, such as pseudoxanthoma elasticum. Rheumatologists are strongly encouraged to take part in a multidisciplinary approach to the management of this debilitating disease.

Inducing indel mutation in the SOX6 gene by zinc finger nuclease for gamma reactivation: An approach towards gene therapy of beta thalassemia

β-thalassemia is a common autosomal recessive disorder characterized by a deficiency in the synthesis of β-chains. Evidences show that increased HbF levels improve the symptoms in patients with β-thalassemia or sickle cell anemia. In this study, ZFN technology was applied to induce a mutation in the binding domain region of SOX6 to reactivate γ-globin expression. The sequences coding for ZFP arrays were designed and sub cloned in TDH plus as a transfer vector. The ZFN expression was confirmed using Western blot analysis. In the next step, using the site-directed mutagenesis strategy through the overlap PCR, a missense mutation (D64V) was induced in the catalytic domain of the integrase gene in the packaging plasmid and verified using DNA sequencing. Then, the integrase minus lentivirus containing ZFN cassette was packaged. Transduction of K562 cells with this virus was performed. Mutation detection assay was performed. The indel percentage of the cells transducted with lenti virus containing ZFN was 31%. After 5 days of erythroid differentiation with 15 μg/mL cisplatin, the levels of γ-globin mRNA were sixfold in the cells treated with ZFN compared to untreated cells. In the meantime, the measurement of HbF expression levels was carried out using hemoglobin electrophoresis and showed the same results. Integrase minus lentivirus can provide a useful tool for efficient transient gene expression and helps avoid disadvantages of gene targeting using the native virus. The ZFN strategy applied here to induce indel on SOX6 gene in adult erythroid progenitors may provide a method to activate fetal hemoglobin expression in individuals with β-thalassemia.

Co-inheritance of HBB:c.-106G > C, a rare single nucleotide variation at position -56 relative to transcription initiation site, with other known mutations in the globin clusters

OBJECTIVES

We performed molecular analysis to evaluate clinical implications of a rare nucleotide change, particularly when co-inherited with other known mutations in the globin clusters, in order to conduct an appropriate genetic counselling.

METHODS

Complete blood cell counts and high-performance liquid chromatography were the routine first level analysis for patients referred to our Hospital Center in Palermo to undergo the screening test for haemoglobinopathies. Sequencing analysis was the selected method for the phenotypic characterization, especially in case of new or very rare mutations in globin genes.

RESULTS

We report data of a rare single nucleotide variation at position -56 relative to transcription initiation site (NM_000518.4(HBB):c.-106G > C), identified in ten patients of Italian origin during the screening programme of the 'Sicilian population'. It was found in simple heterozygosity (n = 8), in association with beta haemoglobin variant Hb S (n = 1) and in heterozygosity with beta-thalassaemic allele IVS-I-1 G->A [(HBB):c.92 + 1G > A] and ααα ^anti3.7 rearrangement (n = 1).

DISCUSSION

Heterozygous subjects for this substitution showed normal haematological and electrophoretic features. Heterozygotes for this mutation and other defect in globin genes showed the classical phenotype of a healthy carrier, therefore it can be considered a benign variant that does not alter the production and function of haemoglobin.

CONCLUSION

This is another example of rare or new nucleotide variations whose identification and characterization is crucial in order to carry out appropriate genetic counselling to a potential risk couple.

A Universal Approach to Correct Various HBB Gene Mutations in Human Stem Cells for Gene Therapy of Beta-Thalassemia and Sickle Cell Disease

Beta-thalassemia is one of the most common recessive genetic diseases, caused by mutations in the HBB gene. Over 200 different types of mutations in the HBB gene containing three exons have been identified in patients with β-thalassemia (β-thal) whereas a homozygous mutation in exon 1 causes sickle cell disease (SCD). Novel therapeutic strategies to permanently correct the HBB mutation in stem cells that are able to expand and differentiate into erythrocytes producing corrected HBB proteins are highly desirable. Genome editing aided by CRISPR/Cas9 and other site-specific engineered nucleases offers promise to precisely correct a genetic mutation in the native genome without alterations in other parts of the human genome. Although making a sequence-specific nuclease to enhance correction of a specific HBB mutation by homology-directed repair (HDR) is becoming straightforward, targeting various HBB mutations of β-thal is still challenging because individual guide RNA as well as a donor DNA template for HDR of each type of HBB gene mutation have to be selected and validated. Using human induced pluripotent stem cells (iPSCs) from two β-thal patients with different HBB gene mutations, we devised and tested a universal strategy to achieve targeted insertion of the HBB cDNA in exon 1 of HBB gene using Cas9 and two validated guide RNAs. We observed that HBB protein production was restored in erythrocytes derived from iPSCs of two patients. This strategy of restoring functional HBB gene expression will be able to correct most types of HBB gene mutations in β-thal and SCD. Stem Cells Translational Medicine 2018;7:87-97.

Cat-D: a targeted sequencing method for the simultaneous detection of small DNA mutations and large DNA deletions with flexible boundaries

We developed a targeted DNA sequencing method that is capable of detecting a comprehensive panel of DNA mutations including small DNA mutations and large DNA deletions with unknown/flexible boundaries. The method directly identifies the large DNA deletions (Cat-D) without relying on sequencing coverage to make the genotype calls. We performed the method to simultaneously detect 10 small DNA mutations in β-thalassemia and 2 large genomic deletions in α-thalassemia from 10 genomic DNA samples. Cat-D was performed on 8 genomic DNA samples in duplicate. The 18 Cat-D samples were combined in one sequencing run. In total, 216 genotype calls were made, and 215 of the genotype calls were accurate. No false negative genotype calls were made. One false positive genotype call was made on one target mutation in one experimental duplicate from a genomic DNA sample. In summary, Cat-D can be developed into a robust, high-throughput and cost-effective method suitable for population-based carrier screens.

The ‑α3.7 deletion in α‑globin genes increases the concentration of fetal hemoglobin and hemoglobin A2 in a Saudi Arabian population

The regions of Al‑Qatif and Al‑Ahssa in the Eastern Province of Saudi Arabia are known for their high prevalence of hemoglobinopathies, including β‑thalassemia and sickle cell anemia. Previously, the α‑gene deletion has been demonstrated as highly prevalent among populations residing in these two regions. The present study was conducted in order to investigate the implications of the α‑globin gene deletion on fetal hemoglobin (HbF) and hemoglobin α2 (HbA2) concentrations in patients with transfusion‑dependent β‑thalassemia. A total of 166 Saudi patients with transfusion‑dependent β‑thalassemia and 337 healthy Saudi patients were included in the study. The ‑α3.7, ‑α4.2, -‑FIL, -‑SEA, -‑MED and -‑(20.5) gene deletions were identified using multiplex α‑globin deletion polymerase chain reaction. The present study revealed that the ‑α3.7 gene deletion is the most prevalent (43.5%) in the Saudi populations that were analyzed and is characterized by the deletion of 3,804 base pairs. Numerous genotypes, namely ‑3.7α2/α1α2, ‑3.7α2/α1α12, ‑3.7α2/‑3.7α2, ‑3.7α2HphI/α1α2HphI, ‑3.7α2/α1‑4.2, ‑3.7α2/α1polyA‑1α2, ‑3.7α12/α1α12, ‑‑FIL/‑3.7α2 and ‑3.7α2/‑3.7α2Hb Villiers le Bel were also identified in the investigated population. Furthermore, a gradual increase in the concentration of HbF and HbA2 in patients with β‑thalassemia and the number of α‑gene deletions was demonstrated; whereas in healthy patients the level of HbA2 was demonstrated to decrease as the number of α‑gene deletions increased. Therefore, it can be concluded that the high HbF concentration in the present study is predominantly associated with other mutations associated with β‑thalassemia rather than α‑globin deletions. Furthermore, the results of the present study also revealed novel α‑gene deletion genotypes prevalent in the population studied, namely α1α2/α1α2HphI, α1α2HphI/α1α2HphI, α1α2/α1α2Hb Handsworth, ‑3.7α2HphI/α1α2HphI, ‑3.7α2/‑3.7α2Hb Villiers le Bel and ‑-MED/α1α2HphI.

Investigation of FoxO3 dynamics during erythroblast development in β-thalassemia major

The FoxO3 transcription factor is a key regulator of oxidative stress and erythroid maturation during erythropoiesis. In this study, we explored the involvement of FoxO3 in severe β-thalassemia. Using primary CD34⁺ hematopoietic progenitor cells from patients with β-thalassemia major, we successfully developed an in vitro model of ineffective erythropoiesis. Based on this model, FoxO3 activity was quantified in single cells using high throughput imaging flow cytometry. This study revealed a significant reduction of FoxO3 activity during the late stage of erythroblast differentiation in β-thalassemia, in contrast to erythropoiesis in normal cells that maintain persistent activation of FoxO3. In agreement with the decreased FoxO3 activity in β-thalassemia, the expression of FoxO3 target genes was also found to decrease, concurrent with elevated phosphorylation of AKT, most clearly at the late stage of erythroid differentiation. Our findings provide further evidence for the involvement of FoxO3 during terminal erythropoiesis and confirm the modulation of the PI3K/AKT pathway as a potential therapeutic strategy for β-thalassemia.

Hydroxyurea for lifelong transfusion-dependent β-thalassemia: A meta-analysis

OBJECTIVE

Chronic blood transfusion remains the most feasible therapeutic option for lifelong transfusion-dependent β-thalassemia (lifelong TDβT). However, it is associated with serious risks and complications. Hydroxyurea (HU), an oral chemotherapeutic drug, is expected to increase hemoglobin levels, thereby minimizing the burden of blood transfusion and its complications. Growing literature over the last twenty years suggests promising results of the use HU in lifelong TDβT; however, its role and safety remain unanswered questions. The objective of this study was to evaluate the clinical efficacy and safety of HU in patients with lifelong TDβT.

METHODS

MEDLINE, EMBASE, Cochrane databases, and major preceding conferences for studies that assessed HU in lifelong TDβT patients were searched. The effect size was estimated as a proportion (responder/sample size).

RESULTS

Eleven observational studies, collectively involving 859 patients, fulfilled eligibility criteria. HU was associated with a significant decrease in transfusion need with complete and overall (≥50%) response rates of 26% [95% confidence interval (CI), 13-41%] and 60% (95% CI, 41-78%), respectively. No serious adverse effects were reported. All of the studies had several limitations, such as lack of a comparison group.

CONCLUSION

HU appears to be effective, well tolerated; however, large randomized clinical trials should be done to confirm such findings.

Thalidomide-induced Stroke in a Child With Thalassemia Major

β-thalassemia major is a hereditary anemia resulting from defects in β-globin production. It is also characterized by a hypercoagulable state with an increased risk of thrombosis. Thalidomide, a drug known for its immunomodulating and antiangiogenic properties, has recently been demonstrated to induce γ-globin gene expression and to increase the proliferation of erythroid cells. An increasing incidence of thromboembolic events in thalidomide-treated patients has been reported. This is often in the context of thalidomide combinations with other drugs, including steroids and particularly anthracycline-based chemotherapy, and with very low incidence of thrombosis with single-agent thalidomide treatment. We report a case of stroke in a β-thalassemic child who had received a course of thalidomide.

Whole transcriptome analysis of human erythropoietic cells during ontogenesis suggests a role of VEGFA gene as modulator of fetal hemoglobin and pharmacogenomic biomarker of treatment response to hydroxyurea in β-type hemoglobinopathy patients

BACKGROUND

Human erythropoiesis is characterized by distinct gene expression profiles at various developmental stages. Previous studies suggest that fetal-to-adult hemoglobin switch is regulated by a complex mechanism, in which many key players still remain unknown. Here, we report our findings from whole transcriptome analysis of erythroid cells, isolated from erythroid tissues at various developmental stages in an effort to identify distinct molecular signatures of each erythroid tissue.

RESULTS

From our in-depth data analysis, pathway analysis, and text mining, we opted to focus on the VEGFA gene, given its gene expression characteristics. Selected VEGFA genomic variants, identified through linkage disequilibrium analysis, were explored further for their association with elevated fetal hemoglobin levels in β-type hemoglobinopathy patients. Our downstream analysis of non-transfusion-dependent β-thalassemia patients, β-thalassemia major patients, compound heterozygous sickle cell disease/β-thalassemia patients receiving hydroxyurea as fetal hemoglobin augmentation treatment, and non-thalassemic individuals indicated that VEGFA genomic variants were associated with disease severity in β-thalassemia patients and hydroxyurea treatment efficacy in SCD/β-thalassemia compound heterozygous patients.

CONCLUSIONS

Our findings suggest that VEGFA may act as a modifier gene of human globin gene expression and, at the same time, serve as a genomic biomarker in β-type hemoglobinopathy disease severity and hydroxyurea treatment efficacy.

Correction of β-thalassemia mutant by base editor in human embryos

β-Thalassemia is a global health issue, caused by mutations in the HBB gene. Among these mutations, HBB -28 (A>G) mutations is one of the three most common mutations in China and Southeast Asia patients with β-thalassemia. Correcting this mutation in human embryos may prevent the disease being passed onto future generations and cure anemia. Here we report the first study using base editor (BE) system to correct disease mutant in human embryos. Firstly, we produced a 293T cell line with an exogenous HBB -28 (A>G) mutant fragment for gRNAs and targeting efficiency evaluation. Then we collected primary skin fibroblast cells from a β-thalassemia patient with HBB -28 (A>G) homozygous mutation. Data showed that base editor could precisely correct HBB -28 (A>G) mutation in the patient's primary cells. To model homozygous mutation disease embryos, we constructed nuclear transfer embryos by fusing the lymphocyte or skin fibroblast cells with enucleated in vitro matured (IVM) oocytes. Notably, the gene correction efficiency was over 23.0% in these embryos by base editor. Although these embryos were still mosaic, the percentage of repaired blastomeres was over 20.0%. In addition, we found that base editor variants, with narrowed deamination window, could promote G-to-A conversion at HBB -28 site precisely in human embryos. Collectively, this study demonstrated the feasibility of curing genetic disease in human somatic cells and embryos by base editor system.

β‑thalassemia caused by compound heterozygous mutations and cured by bone marrow transplantation: A case report

In the present study, a rare familial case of severe thalassemia with compound spontaneous mutations is reported. A 2.5-year-old boy, who suffered from severe anemia with yellowish skin, enlarged liver and spleen, was provided with a blood transfusion every 20 days to maintain hemoglobin levels between 90 and 100 g/l. Sanger sequencing combined with reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Gap-PCR revealed that the proband was a carrier of 4 compound heterozygous mutations: Hemoglobin subunit β (HBB):IVS-II-654(C>T)β⁺; Southeast Asian-type-hereditary persistence of fetal hemoglobin (SEA-HPFH); HBB:c316-148G>T; hemoglobin subunit α2 (HBA2):c.46G>A. The father of the proband was identified as a carrier of the heterozygous SEA-HPFH mutation, the mother was a carrier of compound heterozygous mutations of HBB:IVS-II-654(C>T) and HBA2:c.46G>A, and the elder sister was heterozygous for HBB:IVS-II-654(C>T)β⁺. Based on these genetic results, it was determined that the proband had both of heavy β-thalassemia and α-thalassemia. Upon human leukocyte antigen matching, bone marrow transplantation (BMT) was successfully performed on the proband by selecting his HLA-compatible sister as a donor. Following treatment, the proband was revealed to only carry the IVS-II-654(C>T)β⁺ heterozygous mutation, and further regular blood transfusions have been avoided; BMT results remained normal at six months follow-up.

Benefits of Curcumin Supplementation on Antioxidant Status in β-Thalassemia Major Patients: A Double-Blind Randomized Controlled Clinical Trial

Background: β-Thalassemia major, the most common inherited anemia in the world, is associated with imbalance in the oxidant-antioxidant system. The objective of this study was to evaluate the efficacy of curcumin supplementation on markers of oxidative stress in patients with β-Thalassemia. Methods: This double-blind randomized controlled clinical trial was performed on 61 β-thalassemia major patients. Subjects in the curcumin group received two 500 mg curcumin capsules daily and patients in the placebo group took 2 placebo capsules daily for 12 weeks. Dietary intakes and biochemical parameters were assessed at the beginning and the end of intervention. Results: At the end of the study, serum malondialdehyde (MDA), total and direct bilirubin significantly decreased (p = 0.002, p < 0.001, and p < 0.001, respectively) and total antioxidant capacity significantly increased (p = 0.005) in the curcumin group. Based on the analysis of covariance, a significant reduction in MDA, total and direct bilirubin was also detected in the curcumin group when compared to the placebo group (p = 0.001, p = 0.039, and p = 0.013, respectively). Changes in hemoglobin, serum iron, ferritin, catalase, and vitamin E were not significant in any of the 2 groups. Conclusions: Curcumin supplementation in combination with deferoxamin improved the antioxidant status in β-thalassemia major patients. Curcumin may be useful for the relief of metabolic complications in these patients.

An Aγ-globin G->A gene polymorphism associated with β039 thalassemia globin gene and high fetal hemoglobin production

BACKGROUND

Increase of the expression of γ-globin gene and high production of fetal hemoglobin (HbF) in β-thalassemia patients is widely accepted as associated with a milder or even asymptomatic disease. The search for HbF-associated polymorphisms (such as the XmnI, BCL11A and MYB polymorphisms) has recently gained great attention, in order to stratify β-thalassemia patients with respect to expectancy of the first transfusion, need for annual intake of blood, response to HbF inducers (the most studied of which is hydroxyurea).

METHODS

Aγ-globin gene sequencing was performed on genomic DNA isolated from a total of 75 β-thalassemia patients, including 31 β⁰39/β⁰39, 33 β⁰39/β⁺IVSI-110, 9 β⁺IVSI-110/β⁺IVSI-110, one β⁰IVSI-1/β⁺IVSI-6 and one β⁰39/β⁺IVSI-6.

RESULTS

The results show that the rs368698783 polymorphism is present in β-thalassemia patients in the 5'UTR sequence (+25) of the Aγ-globin gene, known to affect the LYAR (human homologue of mouse Ly-1 antibody reactive clone) binding site 5'-GGTTAT-3'. This Aγ(+25 G->A) polymorphism is associated with the Gγ-globin-XmnI polymorphism and both are linked with the β⁰39-globin gene, but not with the β⁺IVSI-110-globin gene. In agreement with the expectation that this mutation alters the LYAR binding activity, we found that the Aγ(+25 G->A) and Gγ-globin-XmnI polymorphisms are associated with high HbF in erythroid precursor cells isolated from β⁰39/β⁰39 thalassemia patients.

CONCLUSIONS

As a potential explanation of our findings, we hypothesize that in β-thalassemia the Gγ-globin-XmnI/Aγ-globin-(G->A) genotype is frequently under genetic linkage with β⁰-thalassemia mutations, but not with the β⁺-thalassemia mutation here studied (i.e. β⁺IVSI-110) and that this genetic combination has been selected within the population of β⁰-thalassemia patients, due to functional association with high HbF. Here we describe the characterization of the rs368698783 (+25 G->A) polymorphism of the Aγ-globin gene associated in β⁰39 thalassemia patients with high HbF in erythroid precursor cells.