Cognitive impairment and hippocampal neuronal damage in ß-thalassaemia mice.

ß-Thalassaemia is one of the most common genetic diseases worldwide. During the past few decades, life expectancy of patients has increased significantly owing to advance in medical treatments. Cognitive impairment, once has been neglected, has gradually become more documented. Cognitive impairment in ß-thalassaemia patients is associated with natural history of the disease and socioeconomic factors. Herein, to determined effect of ß-thalassaemia intrinsic factors, 22-month-old ß-thalassaemia mouse was used as a model to assess cognitive impairment and to investigate any aberrant brain pathology in ß-thalassaemia. Open field test showed that ß-thalassaemia mice had decreased motor function. However, no difference of neuronal degeneration in primary motor cortex, layer 2/3 area was found. Interestingly, impaired learning and memory function accessed by a Morris water maze test was observed and correlated with a reduced number of living pyramidal neurons in hippocampus at the CA3 region in ß-thalassaemia mice. Cognitive impairment in ß-thalassaemia mice was significantly correlated with several intrinsic ß-thalassaemic factors including iron overload, anaemia, damaged red blood cells (RBCs), phosphatidylserine (PS)-exposed RBC large extracellular vesicles (EVs) and PS-exposed medium EVs. This highlights the importance of blood transfusion and iron chelation in ß-thalassaemia patients. In addition, to improve patients' quality of life, assessment of cognitive functions should become part of routine follow-up.

Economic burden of adult patients with ß-thalassaemia major in mainland China.

BACKGROUND: ß-thalassaemia major poses a substantial economic burden, especially in adults. We aimed to estimate the economic burden of adult patients with ß-thalassaemia major from a societal perspective using the real-world data. According to the clinical guideline, we also estimated the annual medical costs for patients with the same body weight and calculated the lifetime medical costs over 50 years in mainland China. METHODS: This was a retrospective cross-sectional study. An online survey with snowball sampling covering seven provinces was conducted. We extracted patient demographics, caregiver demographics, disease and therapy information, caring burden, and costs for adult patients diagnosed with ß-thalassaemia major and their primary caregivers. In the real world, we estimated the annual direct medical cost, direct nonmedical cost, and indirect cost. In addition, we calculated the annual direct medical cost and lifetime direct medical cost by weight with discounted and undiscounted rates according to the clinical guideline. RESULTS: Direct medical costs was the main driver of total cost, with blood transfusion and iron chelation therapy as the most expensive components of direct medical cost. In addition, adult patients with ß-thalassaemia major weighing 56 kg were associated with an increase of $2,764 in the annual direct medical cost using the real-world data. The undiscounted and discounted (5% discount rate) total lifetime treatment costs were $518,871 and $163,441, respectively. CONCLUSIONS: Patients with ß-thalassaemia major often encounter a substantial economic burden in mainland China. Efforts must be made to help policymakers develop effective strategies to reduce the burden and pevalence of thalassaemia.

Non-invasive prenatal screening & diagnosis of ß-thalassaemia in an affected foetus.

Background & objectives: Non-invasive prenatal testing (NIPT) of maternally inherited alleles of ß-thalassaemia (MIB) remains to be a challenge. Furthermore, current techniques are not available for use as routine tests. NIPT for ß-thalassaemia disease was developed by using a specific droplet digital polymerase chain reaction (ddPCR) assay to analyze the cell-free foetal DNA (cffDNA) derived from maternal plasma. Methods: Pregnant women and their spouses who are at risk of bearing an offspring with ß-thalassaemia disease from common MIB mutations (CD 41/42-TCTT, CD17A>T, IVS1-1G>T and CD26G>A) were enrolled. The ddPCR assay sets were constructed for each of the four mutations. All cell-free DNA samples were first screened for the paternally inherited ß-thalassaemia (PIB) mutation. The PIB-negative samples were considered as non-disease and were not further analyzed. For PIB-positive samples, DNA fragments of 50-300 base pairs in size were isolated and purified, and further analyzed for MIB mutation. The allelic ratio between the mutant and the wild-type was used to determine the presence of MIB in cffDNA. All cases underwent a prenatal diagnosis by amniocentesis for a definite diagnosis. Results: Forty two couples at risk were enrolled. Twenty two samples were positive for PIBs. Among these 22 samples, there were 10 cases with allelic ratio >1.0 (MIB positive). All foetuses with over-represented mutant alleles were further diagnosed with ß-thalassaemia disease; eight with compound heterozygous and two with homozygous mutations. The 20 PIB-negative and 12 MIB-negative foetuses were non-affected. Interpretation & Conclusions: The results of this study suggest that NIPT utilizing the ddPCR assay can be effectively used for the screening and diagnosis of foetal ß-thalassaemia in at risk pregnancies.

Experiences, Knowledge Gaps and Information Needs of Women in Australia with Transfusion Dependent Thalassaemia in Regard to Fertility and Pregnancy.

OBJECTIVES: Transfusion dependent ß-thalassaemia can have significant effects on fertility and is also associated with significant risks in pregnancy. However, little is known about the perspectives of women living with the condition with regards to reproductive issues. The aim of this study was to assess the experience, knowledge and information needs of Australian women living with transfusion dependent ß-thalassaemia in relation to fertility and pregnancy. METHODS: A cross sectional study using an online anonymous survey, self-administered through REDCap, addressing key issues related to the experience, knowledge and information needs of women with transfusion dependent ß-thalassaemia. Descriptive and inferential analysis was conducted using STATA. RESULTS: Sixty participants were included in the analysis. Two-thirds of sexually active, pre-menopausal women were using contraception. Just under half of the participants who were sexually active had children and half had required some form of assisted reproductive technology to achieve a pregnancy. Less than half identified the importance of contraception as part of ensuring optimised pre-pregnancy care, and less than half had accessed pre-pregnancy care. Although there was good understanding of the increased risk of infertility and pregnancy complications, the specific risks and causes of these risks were poorly understood. Around half of the participants indicated they wanted more information on these medical issues. CONCLUSIONS FOR PRACTICE: Our study demonstrated significant concerns and knowledge gaps in Australian women with transfusion dependent ß-thalassaemia with regards to disease-specific issues related to fertility and pregnancy, and a desire for related patient information.

HBB Gene Mutations and Their Pathological Impacts on HbE/ß-Thalassaemia in Kuala Terengganu, Malaysia.

BACKGROUND: ß-thalassaemia is a disorder caused by mutations in the ß-globin gene, leading to defective production of haemoglobins (Hb) and red blood cells (RBCs). It is characterised by anaemia, ineffective erythropoiesis, and iron overload. Patients with severe ß-thalassaemia require lifelong blood transfusions. Haemoglobin E beta-thalassaemia (HbE/ß-thalassaemia) is a severe form of ß-thalassaemia in Asian countries. More than 200 alleles have been recognised in the ß-globin region. Different geographical regions show different frequencies of allelic characteristics. In this study, the spectrum of ß-thalassaemia (ß-thal) alleles and their correlation with iron overload, in HbE/ß-thalassaemia patients, ß-thalassaemia trait, and HbE trait were studied. METHODS: Blood samples (n = 260) were collected from 65 ß-thalassaemia patients, 65 parents (fathers and/or mothers) and 130 healthy control individuals. Haematological analyses, iron profiles, and serum hepcidin levels were examined for all participants. DNA was extracted from patients' and their parents' blood samples, then subjected to PCR amplification. Multiplex amplification refractory mutation system PCR (MARMS-PCR) was conducted for eighteen primers to detect the mutations. RESULTS: There was severe anaemia present in HbE/ß-thalassaemia patients compared to their parents and healthy controls. The ferritin and iron levels were significantly increased in patients compared to their parents and healthy controls (p = 0.001). Two common mutations were detected among the patient group and three mutations were detected among their parents, in addition to seven novel mutations in HbE/ß-thalassaemia patients (explained in results). CONCLUSION: Some mutations were associated with severe anaemia in ß-thalassaemia patients. The detection of mutations is a prognostic marker, and could enhance the appropriate management protocols and improve the haematological and biochemical statuses of ß-thalassaemia patients.

Management of luspatercept therapy in patients with transfusion-dependent ß-thalassaemia.

Patients with transfusion-dependent ß-thalassaemia require lifelong, regular red blood cell transfusions for survival; however, frequent blood transfusions are associated with an increased risk of iron overload, transfusion-transmitted disease and alloimmunization, as well as reduced quality of life. Luspatercept, an erythroid maturation agent that promotes late-stage erythroid maturation independently of erythropoietin, has demonstrated efficacy in reducing transfusion burden in patients with transfusion-dependent ß-thalassaemia. In this review, we discuss treatment initiation, ongoing evaluation, dose adjustment and management of adverse events in transfusion-dependent patients with ß-thalassaemia receiving luspatercept, and we provide guidance on how to determine whether patients are deriving clinical benefit.

Single-cell profiling of ineffective erythropoiesis in a mouse model of ß-thalassaemia intermedia.

Beta-thalassaemia is an inherited haemoglobin disorder characterised by ineffective erythropoiesis (IE). The detailed pathogenesis of IE remains unclear. In this study, we used single-cell RNA sequencing (scRNA-seq) to examine IE in Th3/+ ß-thalassaemic mice. The results showed that the erythroid group was remarkably expanded, and genes involved in biological processes such as iron metabolism, haeme synthesis, protein folding, and response to heat were significantly upregulated from erythroid progenitors to reticulocytes in ß-thalassaemic mice. In particular, we identified a unique cell population close to reticulocytes, named ThReticulocytes, characterised by a high level of heat shock protein 70 (Hsp70) expression and dysregulation of iron metabolism and haeme synthesis signalling. Treatment of ß-thalassaemic mice with the haeme oxygenase inhibitor tin-mesoporphyrin effectively improved the iron disorder and IE, and the ThReticulocyte population and Hsp70 expression were significantly suppressed. This study revealed in detail the progression of IE at the single-cell level and possibly provided clues to find therapeutic targets in thalassaemia.

The Novel Role of the B-Cell Lymphoma/Leukemia 11A (BCL11A) Gene in ß-Thalassaemia Treatment.

ß-thalassaemia is a genetic disorder resulting in a reduction or absence of ß-globin gene expression. Due to the high prevalence of ß-thalassaemia and the lack of available treatment other than blood transfusion and haematopoietic stem cell (HSC) transplantation, the disease represents a considerable burden to clinical and economic systems. Foetal haemoglobin has an appreciated ameliorating effect in ß-haemoglobinopathy, as the γ-globin chain substitutes the ß-globin chain reduction by pairing with the excess α-globin chain in ß-thalassaemia and reduces sickling in sickle cell disease (SCD). BCL11A is a critical regulator and repressor of foetal haemoglobin. Downregulation of BCL11A in adult erythroblasts and cell lines expressing adult haemoglobin led to a significant increase in foetal haemoglobin levels. Disruption of BCL11A erythroid enhancer resulted in disruption of the BCL11A gene solely in the erythroid lineages and increased γ-globin expression in adult erythroid cells. Autologous haematopoietic stem cell gene therapy represents an attractive treatment option to overcome the immune complications and donor availability associated with allogeneic transplantation. Using genome editing technologies, the disruption of BCL11A to induce γ- globin expression in HSCs has emerged as an alternative approach to treat ß-thalassaemia. Targeting the +58 BCL11A erythroid enhancer or BCL11A binding motif at the γ-gene promoter with CRISPR-Cas9 or base editors has successfully disrupted the gene and the binding motif with a subsequent increment in HbF levels. This review outlines the critical role of BCL11A in γ-globin gene silencing and discusses the different genome editing approaches to downregulate BCL11A as a means for ameliorating ß-thalassaemia.

A comprehensive study of immune function and immunophenotyping of white blood cells from ß-thalassaemia/HbE patients on hydroxyurea supports the safety of the drug.

Hydroxyurea (HU) (hydroxycarbamide) is used as a therapeutic option in ß-thalassaemia to increase fetal haemoglobin, which results in a reduced requirement for blood transfusion. However, a potential serious adverse effect of HU is neutropenia. Abnormal neutrophil maturation and function in ß-thalassaemia/HbE patients are well documented. This raises questions about the effect of the drug with regards to the immune response these patients. This study investigated the effects of HU treatment on both innate and adaptive immunity in a cross-sectional study of 28 ß-thalassaemia/HbE patients who had received HU treatment (BE+HU) as compared with 22 ß-thalassaemia/HbE patients who had not received HU (BE-HU) and 26 normal subjects. The expression of PU.1 and C/EBPß, transcription factors, which are associated with neutrophil maturation, was significantly reduced in BE+HU patients as compared with BE-HU patients and normal subjects. Interestingly, C3bR expression on neutrophils and their oxidative burst activity in BE+HU were restored to close to normal levels when compared with BE-HU. There was no observed effect of HU on monocytes, myeloid derived suppressor cells (both granulocytic and monocytic subsets), CD4+ T cells, CD8+ T cells, complement levels and serum immunoglobulin levels in this study. The full immunophenotyping analysis in this study indicates that HU therapy in ß-thalassaemia/HbE patients does not significantly compromise the immune response.

The effect of erythroferrone suppression by transfusion on the erythropoietin-erythroferrone-hepcidin axis in transfusion-dependent thalassaemia: A pre-post cohort study.

To track post-transfusion changes on the erythropoietin (EPO)-erythroferrone (ERFE)-hepcidin axis, we collected blood samples from 82 regularly transfused patients with ß-thalassaemia major (ß-TM) immediately before and 4-6 days after transfusion. The post-transfusion haemoglobin, hepcidin, and ferritin levels were increased, while the EPO, ERFE, and soluble transferrin receptor were suppressed. In addition, hepcidin change was inversely associated with erythropoietic change, which was confirmed by an increase in the hepcidin-to-ERFE ratio after transfusion. Age was the main predictor of serum ERFE, followed by EPO, transfusion frequencies, and ferritin. We found ERFE to be a highly sensitive indicator of erythroid activity in ß-TM and that the hepcidin-to-ERFE ratio after transfusion may be used as an appropriateness index of serum hepcidin regulation relative to the degree of erythropoiesis.

Beta-thalassemia and the advent of new interventions beyond transfusion and iron chelation.

Beta-thalassaemia, including sickle cell anaemia and thalassaemia E, is most common in developing countries in tropical and subtropic regions. Because carriers have migrated there owing to demographic migration, ß-thalassaemia can now be detected in areas other than malaria-endemic areas. Every year, an estimated 300 000-500 000 infants, the vast majority of whom are from developing countries, are born with a severe haemoglobin anomaly. Currently, some basic techniques, which include iron chelation therapy, hydroxyurea, blood transfusion, splenectomy and haematopoietic stem cell transplantation, are being used to manage thalassaemia patients. Despite being the backbone of treatment, traditional techniques have several drawbacks and limitations. Ineffective erythropoiesis, correction of globin chain imbalance and adjustment of iron metabolism are some of the innovative treatment methods that have been developed in the care of thalassaemia patients in recent years. Moreover, regulating the expression of B-cell lymphoma/leukaemia 11A and sex-determining region Y-box through the enhanced expression of micro RNAs can also be considered putative targets for managing haemoglobinopathies. This review focuses on the biological basis of ß-globin gene production, the pathophysiology of ß-thalassaemia and the treatment options that have recently been introduced.

Psychological intervention in children with transfusion-dependent ß-thalassaemia.

BACKGROUND AND OBJECTIVES: Transfusion-dependent ß-thalassaemia can lead to severe psychological issues in paediatric and adolescent patients. However, the psychological interventions for these patients are limited in clinical practice. We aimed to investigate the impact of a 3-month psychological intervention on the quality of life (QOL) of children with ß-thalassaemia (12-18 years old) who relied on blood transfusion in this study. MATERIALS AND METHODS: In the current randomized controlled trial, a total of 143 paediatric or adolescent patients (12-18 years old) with transfusion-dependent ß-thalassaemia were recruited. They were randomized into the control group (n = 71) who received standard physiological treatment and the intervention group (n = 72) who received a 3-month intervention in addition to standard physiological treatment. The effects of the interventions on the QOL and psychological outcomes of these participants were analysed. RESULTS: The 3-month intervention significantly improved the scores of PedsQoL 4.0 Generic Core Scales of paediatric patients with transfusion-dependent ß-thalassaemia. It also significantly improved the psychological status and alleviated the depression among children and adolescent patients by alleviating anhedonia, negative mood and negative self-esteem among them. CONCLUSION: Psychological intervention has positive effects on the treatment for children with transfusion-dependent ß-thalassaemia.

Novel therapies in ß-thalassaemia.

Beta-thalassaemia is one of the most significant haemoglobinopathies worldwide resulting in the synthesis of little or no ß-globin chains. Without treatment, ß-thalassaemia major is lethal within the first decade of life due to the complex pathophysiology, which leads to wide clinical manifestations. Current clinical management for these patients depends on repeated transfusions followed by iron-chelating therapy. Several novel approaches to correct the resulting α/ß-globin chain imbalance, treat ineffective erythropoiesis and improve iron overload are currently being developed. Up to now, the only curative treatment for ß-thalassemia is haematopoietic stem-cell transplantation, but this is a risky and costly procedure. Gene therapy, gene editing and base editing are emerging as a powerful approach to treat this disease. In ß-thalassaemia, gene therapy involves the insertion of a vector containing the normal ß-globin or γ-globin gene into haematopoietic stem cells to permanently produce normal red blood cells. Gene editing and base editing involves the use of zinc finger nucleases, transcription activator-like nucleases and clustered regularly interspaced short palindromic repeats/Cas9 to either correct the causative mutation or else insert a single nucleotide variant that will increase foetal haemoglobin. In this review, we will examine the current management strategies used to treat ß-thalassaemia and focus on the novel therapies targeting ineffective erythropoiesis, improving iron overload and correction of the globin chain imbalance.

A Novel Algorithm Using Cell Population Data (VCS Parameters) as a Screening Discriminant between Alpha and Beta Thalassemia Traits.

Thalassemia is one of the major inherited haematological disorders in the Southeast Asia region. This study explored the potential utility of red blood cell (RBC) parameters and reticulocyte cell population data (CPD) parameters in the differential diagnosis of α and ß-thalassaemia traits as a rapid and cost-effective tool for screening of thalassemia traits. In this study, a total of 1597 subjects (1394 apparently healthy subjects, 155 subjects with α-thalassaemia trait, and 48 subjects with ß-thalassaemia trait) were accrued. The parameters studied were the RBC parameters and reticulocyte CPD parameters derived from Unicel DxH800. A novel algorithm named αß-algorithm was developed: (MN-LMALS-RET × RDW) - MCH) to discriminate α from ß-thalassaemia trait with a cut-off value of 1742.5 [AUC = 0.966, sensitivity = 92%, specificity = 90%, 95% CI = 0.94-0.99]. Two prospective studies were carried: an in-house cohort to assess the specificity of this algorithm in 310 samples comprising various RBC disorders and in an interlaboratory cohort of 65 α-thalassemia trait, and 30 ß-thalassaemia trait subjects to assess the reproducibility of the findings. We propose the αß-algorithm to serve as a rapid, inexpensive surrogate evaluation tool of α and ß-thalassaemia in the population screening of thalassemia traits in geographic regions with a high burden of these inherited blood disorders.

Genetic and Epigenetic Therapies for ß-Thalassaemia by Altering the Expression of α-Globin Gene.

ß-Thalassaemia is caused by over 300 mutations in and around the ß-globin gene that lead to impaired synthesis of ß-globin. The expression of α-globin continues normally, resulting in an excess of α-globin chains within red blood cells and their precursors. These unpaired α-globin chains form unstable α-hemichromes that trigger cascades of events to generate reactive oxygen species, leading to ineffective erythropoiesis and haemolysis in patients with ß-thalassaemia. The clinical genetic data reported over several decades have demonstrated how the coinheritance of α-thalassaemia ameliorates the disease phenotype of ß-thalassaemia. Thus, it is evident that down-regulation of the α-globin gene expression in patients with ß-thalassaemia could ameliorate or even cure ß-thalassaemia. Over the last few years, significant progress has been made in utilising this pathway to devise a cure for ß-thalassaemia. Most research has been done to alter the epigenetic landscape of the α-globin locus or the well-characterised distant enhancers of α-globin. In vitro, pre-clinical studies on primary human erythroid cells have unveiled inhibition of histone lysine demethylation and histone deacetylation as potential targets to achieve selective downregulation of α-globin through epigenetic drug targeting. CRISPR based genome editing has been successfully used in vitro to mutate α-globin genes or enhancers of α-goblin to achieve clinically significant knockdowns of α-globin to the levels beneficial for patients with ß-thalassaemia. This review summarises the current knowledge on the regulation of human α-globin genes and the clinical genetic data supporting the pathway of targeting α-globin as a treatment for ß-thalassaemia. It also presents the progress of epigenetic drug and genome editing approaches currently in development to treat ß-thalassaemia.

TEA domain transcription factor 4 modulates repression of fetal haemoglobin by direct binding to the γ-globin gene promoters.

Re-activation of fetal haemoglobin (HbF) has been proved to be an effective strategy for the treatment of ß-haemoglobinopathies. In this study, we identified TEA domain transcription factor 4 (TEAD4) as a new potential regulator of HbF by integrating public data sets with quantitative polymerase chain reaction analysis in ß-thalassaemia patients. Significant negative correlation was observed between the expression of TEAD4 and HbF levels in ß-thalassaemia patients. Functional validations of TEAD4 inhibition in both ß-thalassaemia CD34+ cells and HUDEP-2 cells indicated that depletion of TEAD4 led to a significant increase of HbF. Finally, we identified a binding motif of TEAD4 on γ-globin gene promoters; its disruption consistently led to de-repression of HbF. Taken together, these results demonstrate that TEAD4 could act as a transcriptional inhibitor of the γ-globin gene through direct binding on its promoter. Our findings demonstrate a novel role of TEAD4 on the regulation of HbF, which may benefit patients with ß-haemoglobinopathies.

Haemoglobin switching modulator SNPs rs5006884 is associated with increased HbA2 in ß-thalassaemia carriers.

INTRODUCTION: Haemoglobin A2 (HbA2), the tetramer of α- and δ-globin chains, is used as a diagnostic biomarker for ß-thalassaemia carriers. The HbA2 levels are regulated by the presence of HPFH, δ-thalassaemia, HbA1/2 gene triplication, and variants of KLF1, ß-globin gene, and HbF regulating QTLs. Saudi Arabia has a high incidence of borderline HbA2 levels, thereby making it difficult to classify the haemoglobinopathies. This study aims to investigate the association of known HbF enhancer QTL gene SNPs with HbA2 levels. MATERIAL AND METHODS: 14 Specific SNPs in BCL11A, HMIP, OR51B6, HBBP1, and HBG2 loci were genotyped in 164 Saudi ß-thalassaemia carriers by TaqMan assay to validate their role as regulators of HbA2 levels. HbA2 levels were determined using the Variant II ß-Thalassemia Short Program Recorder kit. The non-random association of these SNPs was tested using HaploView software. Protein interaction was assessed using 3D structure modelling for OR51B6 (rs5006884), comparative energy minimisation, and root-mean-square deviation (RMSD) prediction. RESULTS: Elevated HbA2 levels were associated with SNPs in HBBP1, OR51B6, and TCT haplotype from HBG2 promoter region. The bioinformatics modelling and prediction revealed that the exonic rs5006884 had RMSD value deviations and significantly varied binding energy minimisation. α-globin variations were found in 57.92% of individuals but were not associated with elevated HbA2. CONCLUSIONS: The haemoglobin switching modulators rs2071348, rs7482144, and rs5006884 are involved in regulation of HbA2 level with rs5006884 influencing the tetramer formation. Screening for haemoglobinopathies should take these SNPs into consideration, specifically in borderline HbA2 cases. Assiduous analysis of rs5006884 as HbA2 modulator for amelioration of disease severity is recommended.

The wide spectrum of ß-thalassaemia intermedia-induced pulmonary hypertension: two case reports on the possible role of specific pulmonary arterial hypertension therapy.

Pulmonary hypertension (PH) development remains a significant cardiovascular complication of haemoglobinopathies, severely affecting the morbidity and mortality of such patients. According to the 5th World Symposium on PH, PH related with chronic haemolytic anaemias is classified in group 5, mainly due to the multifactorial pathophysiology of PH in this patient population. There are no clear guidelines regarding the management of PH in patients with haemoglobinopathies; the use of specific pulmonary arterial hypertension (PAH) therapy in patients with ß-thalassaemia and PH is based on data derived from other forms of PH, expert opinion and small series or case reports. The existing knowledge on the use of specific-PAH therapy in ß-thalassaemia patients with PH is limited, and in most cases the diagnosis of PH is based on echocardiographic findings only. We herein report two patients with ß-thalassaemia intermedia (TI) and PH, who got same initial approach but different outcome, to highlight the wide spectrum of TI-induced PH, the importance of optimal disease-directed therapy and the possible role of specific-PAH therapy. We also emphasize the central role of right heart catheterization in the diagnosis and follow-up of PH, since this information does facilitate the suitable use or withdrawal of specific PAH drugs in these patients.

GATA zinc finger domain-containing protein 2A (GATAD2A) deficiency reactivates fetal haemoglobin in patients with ß-thalassaemia through impaired formation of methyl-binding domain protein 2 (MBD2)-containing nucleosome remodelling and deacetylation (NuRD) complex.

Reactivation of fetal haemoglobin (HbF) expression is an effective way to treat ß-thalassaemia and sickle cell anaemia. In the present study, we identified a novel GATA zinc finger domain-containing protein 2A (GATAD2A) mutation, which contributed to the elevation of HbF and ameliorated clinical severity in a patient with ß-thalassaemia, by targeted next-generation sequencing. Knockout of GATAD2A led to a significant induction of HbF in both human umbilical cord blood-derived erythroid progenitor-2 (HUDEP-2) and human cluster of differentiation (CD)34+ cells with a detectable impact on erythroid differentiation. Furthermore, heterozygous knockout of GATAD2A impaired recruitment of chromodomain helicase DNA-binding protein 4 (CHD4) to the methyl-binding domain protein 2 (MBD2)-containing nucleosome remodelling and deacetylation (NuRD) complex. Our present data suggest that mutations causing the haploinsufficiency of GATAD2A might contribute to amelioration of clinical severity in patients with ß-thalassaemia.

The worldwide molecular spectrum and distribution of thalassaemia: a systematic review.

CONTEXT: Thalassaemia is one of the most common inherited autosomal recessive disorders around the world. A considerable amount of literature has been published about the type of mutations and the prevalence of thalassaemia, but findings are often contradictory. OBJECTIVE: This systematic review aimed to provide a comprehensive view of the prevalence of thalassaemia-associated mutations in different countries, their effect on haemoglobin (Hb) levels, as well as reporting thalassaemia-associated rare mutations. METHODS: A systematic search of the literature was carried out through major indexing databases (MEDLINE/PubMed, Scopus, EMBASE, Cochrane central, and ISI web of science) using keywords: "Co-inheritance, αα, ß, thalassaemia" and "α-ß thalassaemia, Mediterranean anemia, mutations" from 1998-September 2019. Hand-searching was also performed. There was no language restriction. RESULTS: The initial searches yielded 1059 studies, of which 92 articles were included following inclusion and exclusion criteria. Of these, 3.3% (3) of articles were cohort studies, and 96.7% (89) of the remaining articles were cross-sectional studies. Our findings showed that 45.6% (42) of researchers investigated ß-thalassaemia, 22.9% (21) αα-ß thalassaemia, and 31.5% (29) α thalassaemia. CONCLUSION: The present study provides valuable information about the spectrum of thalassaemia-associated mutations, which can be useful for preventing thalassaemia, reducing costs of care, reducing the treatment-related side effects, and showing the most defective mutations.HighlightEvaluating the increase or decrease in the birth prevalence of thalassaemiaIdentifying the most common and rare mutations in various parts of the worldComparing researchers' findings from various parts of the world.