Thalassaemia

Upregulation of miR‑6747‑3p affects red blood cell lineage development and induces fetal hemoglobin expression by targeting BCL11A in β‑thalassemia

In β‑thalassemia, excessive α‑globin chain impedes the normal development of red blood cells resulting in anemia. Numerous miRNAs, including miR‑6747‑3p, are aberrantly expressed in β‑thalassemia major (β‑TM), but there are no reports on the mechanism of miR‑6747‑3p in regulating red blood cell lineage development and fetal hemoglobin (HbF) expression. In the present study, RT‑qPCR was utilized to confirm miR‑6747‑3p expression in patients with β‑TM and the healthy controls. Electrotransfection was employed to introduce the miR‑6747‑3p mimic and inhibitor in both HUDEP‑2 and K562 cells, and red blood cell lineage development was evaluated by CCK‑8 assay, flow cytometry, Wright‑Giemsa staining and Benzidine blue staining. B‑cell lymphoma/leukemia 11A (BCL11A) was selected as a candidate target gene of miR‑6747‑3p for further validation through FISH assay, dual luciferase assay and Western blotting. The results indicated that miR‑6747‑3p expression was notably higher in patients with β‑TM compared with healthy controls and was positively related to HbF levels. Functionally, miR‑6747‑3p overexpression resulted in the hindrance of cell proliferation, promotion of cell apoptosis, facilitation of cellular erythroid differentiation and γ‑globin expression in HUDEP‑2 and K562 cells. Mechanistically, miR‑6747‑3p could specifically bind to the 546‑552 loci of BCL11A 3'‑UTR and induce γ‑globin expression. These data indicate that upregulation of miR‑6747‑3p affects red blood cell lineage development and induces HbF expression by targeting BCL11A in β‑thalassemia, highlighting miR‑6747‑3p as a potential molecular target for β‑thalassemia therapy.

Leveraging Multi-Omics Approaches and Advanced Technologies to Unravel the Molecular Complexities, Modifiers, and Precision Medicine Strategies for Hemoglobin H Disease

Hemoglobin H (HbH) disease, a form of alpha-thalassemia, poses significant clinical challenges due to its complex molecular underpinnings. It is characterized by reduced synthesis of the alpha-globin chain. The integration of multi-omics and precision medicine holds immense potential to comprehensively understand and capture interactions at the molecular and genetic levels. This review integrates current multi-omics approaches and advanced technologies in HbH research. Furthermore, it delves into detailed pathophysiology and possible therapeutics in the upcoming future. We explore the role of genomics, transcriptomics, proteomics, and metabolomics studies, alongside bioinformatics tools and gene-editing technologies like CRISPR/Cas9, to identify genetic modifiers, decipher molecular pathways, and discover therapeutic targets. Recent advancements are unveiling novel genetic and epigenetic modifiers impacting HbH disease severity, paving the way for personalized precision medicine interventions. The significance of multi-omics research in unraveling the complexities of rare diseases like HbH is underscored, highlighting its potential to revolutionize clinical practice through precision medicine approaches. This paradigm shift can pave the way for a deeper understanding of HbH complexities and improved disease management.

Global Trends on β-Thalassemia Research Over 10 Years: A Bibliometric Analysis

Purpose

Thalassemia, an inherited quantitative globin disorder, is the most prevalent monogenic disease globally. While severe alpha thalassemia results in intrauterine death, β-thalassemia manifests during childhood due to the "second conversion of hemoglobin", garnering increased attention in recent decades.

Methods

In this study, a bibliometric analysis was conducted of thalassemia articles published in the Web of Science Core Collection database between 2013 and 2023 to establish a comprehensive overview and to identify emerging trends. A total of 5655 studies published between 2013 and 2023 were systematically retrieved, and annual publications demonstrated a steady increase, maintaining a high level over the past decade.

Results

The United States contributed the highest number of publications, followed by China. Notably, the journal Blood emerged as the leading authority in β-thalassemia research. Analysis of research hotspots revealed that the pathogenesis of β-thalassemia is primarily linked to iron overload, anemia, gene mutations, and ineffective erythropoiesis. Furthermore, recent studies focusing on gene editing therapies present promising avenues for future investigation.

Conclusion

These findings grasp the research status of β-thalassemia and shed new light on future research frontiers.

Immune modulation permits tolerance and engraftment in a murine model of late-gestation transplantation

ABSTRACT

In utero hematopoietic cell transplantation is an experimental nonmyeloablative therapy with potential applications in hematologic disorders, including sickle cell disease (SCD). Its clinical utility has been limited due to the early acquisition of T-cell immunity beginning at ∼14 weeks gestation, posing significant technical challenges and excluding treatment fetuses evaluated after the first trimester. Using murine neonatal transplantation at 20 days postcoitum (DPC) as a model for late-gestation transplantation (LGT) in humans, we investigated whether immune modulation with anti-CD3 monoclonal antibody (mAb) could achieve donor-specific tolerance and sustained allogeneic engraftment comparable with that of the early-gestation fetal recipient at 14 DPC. In allogeneic wild-type strain combinations, administration of anti-CD3 mAb with transplantation resulted in transient T-cell depletion followed by central tolerance induction confirmed by donor-specific clonal deletion and skin graft tolerance. Normal immune responses to third-party major histocompatibility complex and viral pathogens were preserved, and graft-versus-host disease did not occur. We further demonstrated the successful application of this approach in the Townes mouse model of SCD. These findings confirm the developing fetal T-cell response as a barrier to LGT and support transient T-cell depletion as a safe and effective immunomodulatory strategy to overcome it.

Skin complications during iron chelation therapy for beta-thalassemia: overview and treatment approach

Thalassemia is an inherited genetic disorder of hemoglobin that affects a large population worldwide, and it is estimated that between 50,000 and 60,000 infants with thalassemia are born each year. The most common treatment for thalassemia is blood transfusion, which leads to iron overload. This in itself is a serious clinical condition, and is commonly managed with iron chelation therapy. However, iron chelators can cause various skin complications, including hyperpigmentation, skin rash, itching, and photosensitivity. These skin side effects can impact patients' quality of life. Therefore, this article provides a comprehensive overview of skin complications caused by iron chelators, along with a proposed comprehensive approach to their management in patients with beta-thalassemia. Key strategies include patient education, regular skin assessment, sun protection measures, symptomatic relief with topical corticosteroids and antihistamines, and consideration of treatment modification if severe complications occur. Collaboration between hematologists and dermatologists, along with psychological support and regular follow-up, is an essential component of this multidisciplinary approach. By implementing these strategies, healthcare providers can optimize skin care for patients with beta-thalassemia treated with iron chelators and improve their quality of life.

Speckle tracking echocardiography and β-thalassemia major. A systematic review

Heart disease is among the primary causes of morbidity and mortality in β-thalassemia major (β-TM). Conventional echocardiography has failed to identify myocardial dysfunction at an early stage among these patients, thus speckle tracking echocardiography (STE) has been lately used. The objectives of this review were to 1) identify all published studies having evaluated myocardial strain among β-TM patients, 2) gather their results, 3) compare their findings and 4) propose recommendations based on these data. Literature search was conducted in PubMed, SCOPUS and Cohrane Library. Data regarding left ventricular global longitudinal (LV-GLS), circumferential (LV-GCS) and radial strain (LV-GRS), right ventricular longitudinal strain (RV-GLS), left and right atrial strain were extracted. Thirty-five studies (34 original articles and 1 meta-analysis) have met the inclusion criteria. LV-GLS has been reported being worse in patients compared to controls in 13 of 21 studies, LV-GCS in 7 of 11 studies, LV-GRS in 6 of 7 studies, RV-GLS in 2 of 3 studies and left atrial strain in all case-control studies. Myocardial iron overload (MIO) patient subgroups had worse LV-GLS in 6 of 15 studies, LV-GCS in 2 of 7 studies and LV-GRS in none of 7 studies. A small number of studies suggest left atrial strain correlation with electrical atrial ectopy and atrial fibrillation. It is suggested that STE should be applied supplementary to conventional echocardiography for early identification of myocardial dysfunction among β-TM patients. Potential myocardial strain utilities could be screening for myocardial iron overload, left ventricular diastolic dysfunction and atrial fibrillation.

Active spread of β-thalassemia beyond the thalassemia belt: A study on a Russian population

β-Thalassemia is a disease traditionally associated with thalassemia belt countries. Nonetheless, as global migration intensifies, β-thalassemia-causing variants spread far from their origin. We investigated this process to detect some patterns underlying its course. We analyzed β-thalassemia-causing variants and the origin of 676 unrelated participants in Moscow, the largest city of Russia, far away from the thalassemia belt. Our analyses revealed that modern Russia has one of the broadest spectra of thalassemia-causing variants: 46 different variants, including two novel β0 variants. Only a small proportion of the reported pathogenic variants likely originated in the resident subpopulation. Almost half of the variants that supposedly had emerged outside the Russian borders have already been assimilated by (were found in) the resident subpopulation. The primary modern source of immigration transferring thalassemia to a nonthalassemic part of Russia is the Caucasus region. We also found traces of ancient migration flows from non-Caucasus countries. Our data indicate that β-thalassemia-causing variants are actively spilling over into resident populations of countries outside thalassemia belt regions. Therefore, viewing thalassemia as a disease exclusive to specific ethnic groups creates a mind trap that can complicate the diagnosis.

Back-to-Back Comparison of Third-Generation Sequencing and Next-Generation Sequencing in Carrier Screening of Thalassemia

CONTEXT.—

Recently, new technologies, such as next-generation sequencing and third-generation sequencing, have been used in carrier screening of thalassemia. However, there is no direct comparison between the 2 methods in carrier screening of thalassemia.

OBJECTIVE.—

To compare the clinical performance of third-generation sequencing with next-generation sequencing in carrier screening of thalassemia.

DESIGN.—

Next-generation sequencing and third-generation sequencing were simultaneously conducted for 1122 individuals in Hainan Province.

RESULTS.—

Among 1122 genetic results, 1105 (98.48%) were concordant and 17 (1.52%) were discordant between the 2 methods. Among the 17 discordant results, 4 were common thalassemia variants, 9 were rare thalassemia variants, and 4 were variations with unknown pathogenicity. Sanger sequencing and polymerase chain reaction for discordant samples confirmed all the results of third-generation sequencing. Among the 685 individuals with common and rare thalassemia variants detected by third-generation sequencing, 512 (74.74%) were carriers of α-thalassemia, 110 (16.06%) were carriers of β-thalassemia, and 63 (9.20%) had coinheritance of α-thalassemia and β-thalassemia. Three thalassemia variants were reported for the first time in Hainan Province, including -THAI, -α2.4, and ααααanti3.7. Eleven variants with potential pathogenicity were identified in 36 patients with positive hemoglobin test results. Among 52 individuals with negative hemoglobin test results, 17 were identified with thalassemia variants. In total, third-generation sequencing and next-generation sequencing correctly detected 763 and 746 individuals with variants, respectively. Third-generation sequencing yielded a 2.28% (17 of 746) increment compared with next-generation sequencing.

CONCLUSIONS.—

Third-generation sequencing was demonstrated to be a more accurate and reliable approach in carrier screening of thalassemia compared with next-generation sequencing.

Therapeutic Relevance of Inducing Autophagy in β-Thalassemia

The β-thalassemias are inherited genetic disorders affecting the hematopoietic system. In β-thalassemias, more than 350 mutations of the adult β-globin gene cause the low or absent production of adult hemoglobin (HbA). A clinical parameter affecting the physiology of erythroid cells is the excess of free α-globin. Possible experimental strategies for a reduction in excess free α-globin chains in β-thalassemia are CRISPR-Cas9-based genome editing of the β-globin gene, forcing "de novo" HbA production and fetal hemoglobin (HbF) induction. In addition, a reduction in excess free α-globin chains in β-thalassemia can be achieved by induction of the autophagic process. This process is regulated by the Unc-51-like kinase 1 (Ulk1) gene. The interplay with the PI3K/Akt/TOR pathway, with the activity of the α-globin stabilizing protein (AHSP) and the involvement of microRNAs in autophagy and Ulk1 gene expression, is presented and discussed in the context of identifying novel biomarkers and potential therapeutic targets for β-thalassemia.

A novel discriminant algorithm for differential diagnosis of mild to moderate thalassemia and iron deficiency anemia

BACKGROUND

Mild to moderate thalassemia trait (TT) and iron deficiency anemia (IDA) are the most common conditions of microcytic hypochromic anemia (MHA) and they exhibit highly similar clinical and laboratory features. It is sometimes difficult to make a differential diagnosis between TT and IDA in clinical practice. Therefore, a simple, effective, and reliable index is needed to discriminate between TT and IDA.

METHODS

Data of 598 patients (320 for TT and 278 for IDA) were enrolled and randomly assigned to training set (278 of 598, 70%) and validation set (320 of 598, 30%). Stepwise discriminant analysis was used to define the best diagnostic formula for the discrimination between TT and IDA in training set. The accuracy and diagnostic performance of formula was tested and verified by receiver operating characteristic (ROC) analysis in validation set and its diagnostic performance was compared with other published indices.

RESULTS

A novel formula, Thalassemia and IDA Discrimination Index (TIDI) = -13.932 + 0.434 × RBC + 0.033 × Hb + 0.025 ×MCHC + 53.593 × RET%, was developed to discriminate TT from IDA. TIDI showed a high discrimination performance in ROC analysis, with the Area Under the Curve (AUC) = 0.936, Youden' s index = 78.7%, sensitivity = 89.5%, specificity = 89.2%, respectively. Furthermore, the formula index also obtained a good classification performance in distinguishing 5 common genotypes of TT from IDA (AUC from 0.854-0.987).

CONCLUSION

The new, simple algorithm can be used as an effective and robust tool for the differential diagnosis of mild to moderate TT and IDA in Guangxi region, China.

Third-generation sequencing identified a novel complex variant in a patient with rare alpha-thalassemia

BACKGROUND

Thalassemias represent some of the most common monogenic diseases worldwide and are caused by variations in human hemoglobin genes which disrupt the balance of synthesis between the alpha and beta globin chains. Thalassemia gene detection technology is the gold standard to achieve accurate detection of thalassemia, but in clinical practice, most of the tests are only for common genotypes, which can easily lead to missing or misdiagnosis of rare thalassemia genotypes.

CASE PRESENTATION

We present the case of an 18-year-old Chinese female with abnormal values of routine hematological indices who was admitted for genetic screening for thalassemia. Genomic DNA was extracted and used for the genetic assays. Gap polymerase chain reaction and agarose gel electrophoresis were performed to detect HBA gene deletions, while PCR-reverse dot blot hybridization was used to detect point mutations in the HBA and HBB genes. Next-generation sequencing and third-generation sequencing (TGS) were used to identify known and potentially novel genotypes of thalassemia. We identified a novel complex variant αHb WestmeadαHb Westmeadαanti3.7/-α3.7 in a patient with rare alpha-thalassemia.

CONCLUSIONS

Our study identified a novel complex variant that expands the thalassemia gene variants spectrum. Meanwhile, the study suggests that TGS could effectively improve the specificity of thalassemia gene detection, and has promising potential for the discovery of novel thalassemia genotypes, which could also improve the accuracy of genetic counseling. Couples who are thalassemia carriers have the opportunity to reduce their risk of having a child with thalassemia.

Increased Expression of α-Hemoglobin Stabilizing Protein (AHSP) mRNA in Erythroid Precursor Cells Isolated from β-Thalassemia Patients Treated with Sirolimus (Rapamycin)

Background/Objectives: in β-thalassemia, important clinical complications are caused by the presence of free α-globin chains in the erythroid cells of β-thalassemia patients. These free α-globin chains are present in excess as a result of the lack of β-globin chains to bind with; they tend to aggregate and precipitate, causing deleterious effects and overall cytotoxicity, maturation arrest of the erythroid cells and, ultimately, ineffective erythropoiesis. The chaperone protein α-hemoglobin-stabilizing protein (AHSP) reversibly binds with free α-globin; the resulting AHSP-αHb complex prevents aggregation and precipitation. Sirolimus (rapamycin) has been previously demonstrated to induce expression of fetal hemoglobin and decrease the excess of free α-globin chain in the erythroid cells of β-thalassemia patients. The objective of this study was to verify whether sirolimus is also able to upregulate AHSP expression in erythroid precursor cells (ErPCs) isolated from β-thalassemia patients. Methods: the expression of AHSP genes was analyzed by measuring the AHSP mRNA content by real-time quantitative PCR (RT-qPCR) and the AHSP protein production by Western blotting. Results: AHSP gene expression was found to be higher in ErPCs of β-thalassemia patients in comparison to ErPCs isolated from healthy subjects. In addition, AHSP expression was further induced by treatment of β-thalassemia ErPCs with sirolimus. Finally, AHSP mRNA was expressed at an increased level in ErPCs of sirolimus-treated β-thalassemia patients participating in the NCT03877809 Sirthalaclin clinical trial. Conclusions: this exploratory study suggests that AHSP expression should be considered as an endpoint in clinical trials based on sirolimus.

Pharmacogenomics of Drugs Used in β-Thalassemia and Sickle-Cell Disease: From Basic Research to Clinical Applications

In this short review we have presented and discussed studies on pharmacogenomics (also termed pharmacogenetics) of the drugs employed in the treatment of β-thalassemia or Sickle-cell disease (SCD). This field of investigation is relevant, since it is expected to help clinicians select the appropriate drug and the correct dosage for each patient. We first discussed the search for DNA polymorphisms associated with a high expression of γ-globin genes and identified this using GWAS studies and CRISPR-based gene editing approaches. We then presented validated DNA polymorphisms associated with a high HbF production (including, but not limited to the HBG2 XmnI polymorphism and those related to the BCL11A, MYB, KLF-1, and LYAR genes). The expression of microRNAs involved in the regulation of γ-globin genes was also presented in the context of pharmacomiRNomics. Then, the pharmacogenomics of validated fetal hemoglobin inducers (hydroxyurea, butyrate and butyrate analogues, thalidomide, and sirolimus), of iron chelators, and of analgesics in the pain management of SCD patients were considered. Finally, we discuss current clinical trials, as well as international research networks focusing on clinical issues related to pharmacogenomics in hematological diseases.

Impact of α-Globin Gene Expression and α-Globin Modifiers on the Phenotype of β-Thalassemia and Other Hemoglobinopathies: Implications for Patient Management

In this short review, we presented and discussed studies on the expression of globin genes in β-thalassemia, focusing on the impact of α-globin gene expression and α-globin modifiers on the phenotype and clinical severity of β-thalassemia. We first discussed the impact of the excess of free α-globin on the phenotype of β-thalassemia. We then reviewed studies focusing on the expression of α-globin-stabilizing protein (AHSP), as a potential strategy of counteracting the effects of the excess of free α-globin on erythroid cells. Alternative processes controlling α-globin excess were also considered, including the activation of autophagy by β-thalassemia erythroid cells. Altogether, the studies reviewed herein are expected to have a potential impact on the management of patients with β-thalassemia and other hemoglobinopathies for which reduction in α-globin excess is clinically beneficial.

Identification and characterization of CHD4-associated eRNA as a novel modulator of fetal hemoglobin levels in β-thalassemia

Fetal-to-adult hemoglobin switching is controlled by programmed silencing of γ-globin while the re-activation of fetal hemoglobin (HbF) is an effective strategy for ameliorating the clinical severity of β-thalassemia and sickle cell disease. The identification of enhancer RNAs (eRNAs) related to the fetal (α2γ2) to adult hemoglobin (α2β2) switching remains incomplete. In this study, the transcriptomes of GYPA+ cells from six β-thalassemia patients with extreme HbF levels were sequenced to identify differences in patterns of noncoding RNA expression. It is interesting that an enhancer upstream of CHD4, an HbF-related core subunit of the NuRD complex, was differentially transcribed. We found a significantly positive correlation of eRNA-CHD4 enhancer-gene interaction using the public database of FANTOM5. Specifically, the eRNA-CHD4 expression was found to be significantly higher in both CD34+ HSPCs and HUDEP-2 than those in K562 cells which commonly expressed high level of HbF, suggesting a correlation between eRNA and HbF expression. Furthermore, prediction of transcription binding sites of cis-eQTLs and the CHD4 genomic region revealed a putative interaction site between rs73264846 and ZNF410, a known transcription factor regulating HbF expression. Moreover, in-vitro validation showed that the inhibition of eRNA could reduce the expression of HBG expression in HUDEP-2 cells. Taken together, the findings of this study demonstrate that a distal enhancer contributes to stage-specific silencing of γ-globin genes through direct modulation of CHD4 expression and provide insights into the epigenetic mechanisms of NuRD-mediated hemoglobin switching.

Metabolic regulation of erythrocyte development and disorders

The formation of new red blood cells (RBC) (erythropoiesis) has served as a paradigm for understanding cellular differentiation and developmental control of gene expression. The metabolic regulation of this complex, coordinated process remains poorly understood. Each step of erythropoiesis, including lineage specification of hematopoietic stem cells, proliferation, differentiation, and terminal maturation into highly specialized oxygen-carrying cells, has unique metabolic requirements. Developing erythrocytes in mammals are also characterized by unique metabolic events such as loss of mitochondria with switch to glycolysis, ejection of nucleus and organelles, high-level heme and hemoglobin synthesis, and antioxidant requirement to protect hemoglobin molecules. Genetic defects in metabolic enzymes, including pyruvate kinase and glucose-6-phosphate dehydrogenase, cause common erythrocyte disorders, whereas other inherited disorders such as sickle cell disease and β-thalassemia display metabolic abnormalities associated with disease pathophysiology. Here we describe recent discoveries on the metabolic control of RBC formation and function, highlight emerging concepts in understanding the erythroid metabolome, and discuss potential therapeutic benefits of targeting metabolism for RBC disorders.

Comparison of Third-Generation Sequencing and Routine Polymerase Chain Reaction in Genetic Analysis of Thalassemia

CONTEXT.—

Thalassemia is the most widely distributed monogenic autosomal recessive disorder in the world. Accurate genetic analysis of thalassemia is crucial for thalassemia prevention.

OBJECTIVE.—

To compare the clinical utility of a third-generation sequencing-based approach termed comprehensive analysis of thalassemia alleles with routine polymerase chain reaction (PCR) in genetic analysis of thalassemia and explore the molecular spectrum of thalassemia in Hunan Province.

DESIGN.—

Subjects in Hunan Province were recruited, and hematologic testing was performed. Five hundred four subjects positive on hemoglobin testing were then used as the cohort, and third-generation sequencing and routine PCR were used for genetic analysis.

RESULTS.—

Of the 504 subjects, 462 (91.67%) had the same results, whereas 42 (8.33%) exhibited discordant results between the 2 methods. Sanger sequencing and PCR testing confirmed the results of third-generation sequencing. In total, third-generation sequencing correctly detected 247 subjects with variants, whereas PCR identified 205, which showed an increase in detection of 20.49%. Moreover, α triplications were identified in 1.98% (10 of 504) hemoglobin testing-positive subjects in Hunan Province. Seven hemoglobin variants with potential pathogenicity were detected in 9 hemoglobin testing-positive subjects.

CONCLUSIONS.—

Third-generation sequencing is a more comprehensive, reliable, and efficient approach for genetic analysis of thalassemia than PCR, and allowed for a characterization of the thalassemia spectrum in Hunan Province.

The interactions between ineffective erythropoiesis and ferroptosis in β-thalassemia

In Guangxi, Hainan, and Fujian Province in southern China, β-thalassemia is a frequent monogenic hereditary disorder that is primarily defined by hemolytic anemia brought on by inefficient erythropoiesis. It has been found that ineffective erythropoiesis in β-thalassemia is closely associated with a high accumulation of Reactive oxygen species, a product of oxidative stress, in erythroid cells. During recent years, ferroptosis is an iron-dependent lipid peroxidation that involves abnormalities in lipid and iron metabolism as well as reactive oxygen species homeostasis. It is a recently identified kind of programmed cell death. β-thalassemia patients experience increased iron release from reticuloendothelial cells and intestinal absorption of iron, ultimately resulting in iron overload. Additionally, the secretion of Hepcidin is inhibited in these patients. What counts is both ineffective erythropoiesis and ferroptosis in β-thalassemia are intricately linked to the iron metabolism and Reactive oxygen species homeostasis. Consequently, to shed further light on the pathophysiology of β-thalassemia and propose fresh ideas for its therapy, this paper reviews ferroptosis, ineffective erythropoiesis, and the way they interact.

Super-enhancers include classical enhancers and facilitators to fully activate gene expression

Super-enhancers are compound regulatory elements that control expression of key cell identity genes. They recruit high levels of tissue-specific transcription factors and co-activators such as the Mediator complex and contact target gene promoters with high frequency. Most super-enhancers contain multiple constituent regulatory elements, but it is unclear whether these elements have distinct roles in activating target gene expression. Here, by rebuilding the endogenous multipartite α-globin super-enhancer, we show that it contains bioinformatically equivalent but functionally distinct element types: classical enhancers and facilitator elements. Facilitators have no intrinsic enhancer activity, yet in their absence, classical enhancers are unable to fully upregulate their target genes. Without facilitators, classical enhancers exhibit reduced Mediator recruitment, enhancer RNA transcription, and enhancer-promoter interactions. Facilitators are interchangeable but display functional hierarchy based on their position within a multipartite enhancer. Facilitators thus play an important role in potentiating the activity of classical enhancers and ensuring robust activation of target genes.

Case report: Identification of a novel triplication of alpha-globin gene by the third-generation sequencing: pedigree analysis and genetic diagnosis

BACKGROUND

Thalassemia, a common autosomal hereditary blood disorder worldwide, mainly contains α- and β-thalassemia. The α-globin gene triplicates allele is harmless for carriers, but aggravates the phenotype of β-thalassemia. Therefore, it is particularly crucial to accurately detect the structural variants of α-globin gene clusters.

CASE REPORT

We reported a 28-year-old man, the proband, with microcytic hypochromic anemia. From pedigree analysis, his mother and sister had hypochromic microcytosis, and his father was normal. Genetic testing of thalassemia identified a novel α-globin gene triplicate named αααanti4.2del726bp (NC_000016.10:g.170769_174300dupinsAAAAAA) by third-generation sequencing (TGS) in the proband and his father, which was further validated by multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing. The genotypes of the proband's mother and sister were both -α3.7/αα compounded with heterozygous HBB:c.126_129delCTTT. They were categorized as silent α-thalassemia with co-inheritance of β-thalassemia trait. The proband's genotype additionally had the α-globin gene triplicates compared with his mother and sister, which increased the imbalance between α/β-globin, so the proband had more severe hematological parameters. The proband's wife was diagnosed as HBA2:c.427T > C heterozygosis, and his daughter had the novel α-globin gene triplicates compounded with HBA2:c.427T > C, therefore the girl might be asymptomatic.

CONCLUSION

The identification of the novel α-globin gene triplicates provides more insight for the research of thalassemia variants and indicates that TGS has significant advantages on genetic testing of thalassemia for the reliability, accuracy and comprehensiveness.

Causal links of α-thalassemia indices and cardiometabolic traits and diabetes: MR study

Our study aimed to investigate if genetic variants around 16p13.3's HBA1 locus, associated with erythrocyte indices and HbA1c levels, predict α-thalassemia-related erythrocyte indices, cardiometabolic traits, and diabetes risk in Taiwanese individuals. We analyzed Taiwan Biobank data, including whole-genome sequencing from 1,493 participants and genotyping arrays from 129,542 individuals. First, we performed regional association analysis using whole-genome sequencing data to identify genetic variants significantly associated with erythrocyte indices, confirming their linkage disequilibrium with the α0 thalassemia --SEA deletion mutation, a common cause of α-thalassemia in Southeast Asian populations. Deletion mutation sequencing further validated these variants' association with α-thalassemia. Subsequently, we analyzed genotyping array data, revealing associations between specific genetic variants and cardiometabolic traits, including lipid profiles, HbA1c levels, bilirubin levels, and diabetes risk. Using Mendelian randomization, we established causal relationships between α-thalassemia-related erythrocyte indices and cardiometabolic traits, elucidating their role in diabetes susceptibility. Our findings highlight genetic variants around the α-globin genes as surrogate markers for common α-thalassemia mutations in Taiwan, emphasizing the causal links between α-thalassemia-related erythrocyte indices, cardiometabolic traits, and heightened diabetes risk.

BCL11A-targeted γ-globin gene induction by triterpenoid glycosides of Fagonia indica: A preclinical scientific validation of indigenous herb for the treatment of β-hemoglobinopathies

Pharmacological induction of fetal hemoglobin has proven to be a promising therapeutic intervention in β-hemoglobinopathies by reducing the globin chain imbalance and inhibiting sickle cell polymerization. Fagonia indica has shown therapeutic relevance to β-thalassemia. Therefore, we study the ethnopharmacological potential of Fagonia indica and its biomarker compounds for their HbF induction ability for the treatment of β-thalassemia. Here, we identify, compound 8 (triterpenoid glycosides) of F. indica. as a prominent HbF inducer in-vitro and in-vivo. Compound 8 showed potent erythroid differentiation, enhanced cellular proliferation, ample accumulation of total hemoglobin, and a strong notion of γ-globin gene expression in K562 cultures. Compound 8 treatment also revealed strong induction of erythroid differentiation and fetal hemoglobin mRNA and protein in adult erythroid precursor cells. This induction was associated with simultaneous downregulation of BCL11A and SOX6, and overexpression of the GATA-1 gene, suggesting a compound 8-mediated partial mechanism involved in the reactivation of fetal-like globin genes. The in vivo study with compound 8 (10 mg/kg) in β-YAC mice resulted in significant HbF synthesis demonstrated by the enhanced level of F-cells (84.14 %) and an 8.85-fold increase in the γ-globin gene. Overall, the study identifies compound 8 as a new HbF-inducing entity and provides an early "proof-of-concept" to enable the initiation of preclinical and clinical studies in the development of this HbF-inducing agent for β-thalassemia.

Next-generation sequencing analysis of the molecular spectrum of thalassemia in Southern Jiangxi, China

BACKGROUND

Thalassemia is an extremely prevalent monogenic inherited blood disorder in southern China. It is important to comprehensively understand the molecular spectrum of thalassemia in an area with such a high prevalence of thalassemia before taking appropriate actions for the prevention and treatment of this disorder. Herein, we explored the clinical feasibility of using next-generation sequencing (NGS) for large-scale population screening to illustrate the prevalence and spectrum of thalassemia in Southern Jiangxi.

METHODS

Blood samples collected from 136,312 residents of reproductive age in Southern Jiangxi were characterized for thalassemia by NGS. A retrospective analysis was then conducted on blood samples determined to be positive for thalassemia.

RESULTS

In total, 19,827 (14.545%) subjects were diagnosed as thalassemia carriers, and the thalassemia prevalence rate significantly varied by geographical region (p < 0.001). A total of 40 α-thalassemia genotypes including 21 rare genotypes were identified, with -@-SEA/αα being the most prevalent genotype. 42 β-thalassemia genotypes including 27 rare genotypes were identified, with the most common mutation IVS II-654 C > T accounting for 35.257% of these β-thalassemia genotypes. Furthermore, 74 genotypes were identified among 608 individuals with combined α- and β-thalassemia. Notably, most individuals with rare thalassemia mutations had mildly abnormal hematologic parameters including microcytic hypochromia.

CONCLUSIONS

Our findings demonstrate the great heterogeneity and diverse spectrum of thalassemia in Southern Jiangxi, emphasizing the importance and necessity of persistent prevention and control of thalassemia in this region. Additionally, our findings further suggest that NGS can effectively identify rare mutations and reduce the misdiagnosis rate of thalassemia.

Association of GDF15 levels with body mass index and endocrine status in β-thalassaemia

OBJECTIVE

GDF15 has emerged as a stress-induced hormone, acting on the brain to reduce food intake and body weight while affecting neuroendocrine function. Very high GDF15 levels are found in thalassaemia, where growth, energy balance and neuroendocrine function are impaired. We examined the relationships between GDF15 and anthropometric measures and endocrine status in β-thalassaemia.

DESIGN

Cross sectional study.

PATIENTS

All β-thalassaemia patients attending the thalassaemia unit of Colombo North Teaching Hospital for blood transfusions.

MEASUREMENTS

Anthropometric data, appetite scores, circulating GDF15, IGF, thyroid and reproductive hormone levels in 103 β-thalassaemia patients were obtained.

RESULTS

GDF15 levels were markedly elevated in thalassaemia patients (24.2-fold with β-thalassaemia major compared with healthy controls). Among patients with β-thalassaemia major, the relationship between GDF15 and body mass index (BMI) was curvilinear with all individuals with GDF15 levels above 24,000 pg/mL having a BMI below 20 kg/m2 . After adjustment for BMI, age and Tanner stage, serum IGF1 concentrations correlated negatively with GDF15 in all thalassaemia patients (β = -.027, p = .02). We found a significant positive relationship between GDF15 and gonadotropin (in both sexes) and testosterone (in males).

CONCLUSIONS

GDF15 levels were markedly elevated in patients with β-thalassaemia and its association with BMI is consistent with the known effect of GDF15 to reduce body weight. The inverse association between GDF15 with IGF1 levels may reflect a neuroendocrine impact of GDF15 or an indirect effect via impaired nutritional state. The positive association with testosterone in males and gonadotropins in both sexes, was surprising and should prompt further GDF15 studies on the hypothalamic pituitary gonadal axis.

Prevalence Rate of Thalassemia Carriers among Individuals with Microcytosis or Hypochromia in Portugal

INTRODUCTION

Microcytosis and hypochromia result from deficient hemoglobin synthesis in red blood cells and are easily detected in a complete blood count test. These conditions are mainly due to iron nutritional deficiency, but may also result from some genetic diseases, such as thalassemia. The aim of this study was to determine the contribution of β- and α-thalassemia to these abnormal hematological phenotypes in a representative sample of adult individuals living in Portugal who participated in the first Portuguese National Health Examination Survey (INSEF).

MATERIAL AND METHODS

Among the 4808 INSEF participants, 204 had microcytosis, hypochromia or both. The corresponding 204 DNAs were screened for changes in the β-globin gene by next-generation sequencing and Sanger sequencing. In addition, α-thalassemia deletions within the α-globin cluster were investigated by Gap-PCR and multiplex ligation-dependent probe amplification.

RESULTS

In this selected subgroup of INSEF participants, 54 had α-thalassemia (26%), predominantly caused by the -α3.7kb deletion, and 22 were β-thalassemia carriers (11%) mainly due to point mutations in the β-globin gene previously known in Portugal.

CONCLUSION

Thalassemia trait is a frequent cause of microcytosis or hypochromia in Portugal since this genetic condition was found in 37% of the investigated cases.

Precision Editing as a Therapeutic Approach for β-Hemoglobinopathies

Beta-hemoglobinopathies are the most common genetic disorders worldwide, caused by a wide spectrum of mutations in the β-globin locus, and associated with morbidity and early mortality in case of patient non-adherence to supportive treatment. Allogeneic transplantation of hematopoietic stem cells (allo-HSCT) used to be the only curative option, although the indispensable need for an HLA-matched donor markedly restricted its universal application. The evolution of gene therapy approaches made possible the ex vivo delivery of a therapeutic β- or γ- globin gene into patient-derived hematopoietic stem cells followed by the transplantation of corrected cells into myeloablated patients, having led to high rates of transfusion independence (thalassemia) or complete resolution of painful crises (sickle cell disease-SCD). Hereditary persistence of fetal hemoglobin (HPFH), a syndrome characterized by increased γ-globin levels, when co-inherited with β-thalassemia or SCD, converts hemoglobinopathies to a benign condition with mild clinical phenotype. The rapid development of precise genome editing tools (ZFN, TALENs, CRISPR/Cas9) over the last decade has allowed the targeted introduction of mutations, resulting in disease-modifying outcomes. In this context, genome editing tools have successfully been used for the introduction of HPFH-like mutations both in HBG1/HBG2 promoters or/and in the erythroid enhancer of BCL11A to increase HbF expression as an alternative curative approach for β-hemoglobinopathies. The current investigation of new HbF modulators, such as ZBTB7A, KLF-1, SOX6, and ZNF410, further expands the range of possible genome editing targets. Importantly, genome editing approaches have recently reached clinical translation in trials investigating HbF reactivation in both SCD and thalassemic patients. Showing promising outcomes, these approaches are yet to be confirmed in long-term follow-up studies.

Evaluating the Clinical Utility of a Long-Read Sequencing-Based Approach in Prenatal Diagnosis of Thalassemia

BACKGROUND

The aim is to evaluate the clinical utility of a long-read sequencing-based approach termed comprehensive analysis of thalassemia alleles (CATSA) in prenatal diagnosis of thalassemia.

METHODS

A total of 278 fetuses from at-risk pregnancies identified in thalassemia carrier screening by PCR-based methods were recruited from 9 hospitals, and PCR-based methods were employed for prenatal diagnosis. CATSA was performed retrospectively and blindly for all 278 fetuses.

RESULTS

Among the 278 fetuses, 263 (94.6%) had concordant results and 15 (5.4%) had discordant results between the 2 methods. Of the 15 fetuses, 4 had discordant thalassemia variants within the PCR detection range and 11 had additional variants identified by CATSA. Independent PCR and Sanger sequencing confirmed the CATSA results. In total, CATSA and PCR-based methods correctly detected 206 and 191 fetuses with variants, respectively. Thus, CATSA yielded a 7.9% (15 of 191) increment as compared with PCR-based methods. CATSA also corrected the predicted phenotype in 8 fetuses. Specifically, a PCR-based method showed one fetus had homozygous HBB c.52A > T variants, while CATSA determined the variant was heterozygous, which corrected the predicted phenotype from β-thalassemia major to trait, potentially impacting the pregnancy outcome. CATSA additionally identified α-globin triplicates in 2 fetuses with the heterozygous HBB c.316-197C > T variant, which corrected the predicted phenotype from β-thalassemia trait to intermedia and changed the disease prognosis.

CONCLUSIONS

CATSA represents a more comprehensive and accurate approach that potentially enables more informed genetic counseling and improved clinical outcomes compared to PCR-based methods.

Molecular characterization of a novel homozygous deletion in β-globin cluster causing (δβ)0-Thalassemia among Tunisian family

BACKGROUND

Deletions in the β-globin cluster are uncommon and cause thalassemia (thal) with hereditary persistence of fetal hemoglobin. They constitute a heterogenous group of disorders characterized by absent or reduced synthesis of adult hemoglobin (Hb A) and increased synthesis of fetal hemoglobin (Hb F). Although the clinical severity of these disorders are asymptomatic owing to the increased Hb F levels, the molecular basis is very heterogenous due to the large deletions in the β-globin cluster spanning both HBD and HBB genes. Here, we describe a Tunisian family carrying a novel deletion mutation causing (δβ)°-thalassemia.

METHODS

The amounts of hemoglobin fractions were measured by capillary electrophoresis of hemoglobin. Amplification and sequencing of different regions on the β-gene cluster were performed by Sanger method.

RESULTS

Family study and genetic analysis revealed a large deletion mutation in the β-globin cluster of 14.5 kb (NG_000,007.3:g. 58,253 to g.72837del14584) at the homozygous state in the patient and at heterozygous state at the other members of the family. This deletion removes the HBD and HBB genes.

CONCLUSIONS

In our knowledge, this new large deletion is described for the first time in the Tunisian population and in the world, designed Tunisian(δβ)⁰ in Ithanet database (IthaID: 3971). Therefore, it is important to identify the deletion leading to δβ-thalassemia carriers at the molecular level, to highlight the importance of recognizing the clinical features and implementing appropriate testing to clarify the diagnosis and manage the condition.

Identification of a novel 10.3 kb deletion causing α0-thalassemia by third-generation sequencing: Pedigree analysis and genetic diagnosis

BACKGROUND

α-thalassemia is an inherited blood disorder caused by variants in the α-globin gene cluster. Identification of the pathogenic α-globin gene variants is important for the diagnosis and management of thalassemia.

METHODS

Two suspected families from Xiantao, Hubei Province were recruited in this study. The family members underwent hemoglobin testing. Polymerase Chain Reaction based reverse dot blot (PCR-RDB) was employed to identify the known variants. Next-generation sequencing (NGS) and third-generation sequencing (TGS) were performed to screen the potential disease-causing variants, which were validated by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA).

RESULTS

Hematological analysis suggested that proband A had α-thalassemia traits, and proband B had HbH disease traits. However, only a -α^3.7 mutation had been detected by PCR-RDB and NGS in the proband of family B. Subsequent TGS identified a novel 10.3 kb deletion (NC_000016.10:g.172342-182690del) covering the HBA1, HBQ1 and HBA2 genes in the α-globin gene cluster in both family A and B, which was confirmed by Sanger sequencing and MLPA. These results indicated that the novel deletion is likely responsible for α-thalassemia.

CONCLUSION

A novel α-thalassemia deletion was identified for the two families by TGS. Our work broadened the molecular spectrum of α-thalassemia, and was beneficial for the diagnosis, genetic counseling and management of α-thalassemia.

New logarithm-based discrimination formula for differentiating thalassemia trait from iron deficiency anemia in pregnancy

BACKGROUND

Thalassemia trait (TT) and iron deficiency anemia (IDA) are the most common conditions of microcytic hypochromic anemia (MHA) in pregnant women. Accurate discrimination between TT and IDA is an important issue, and better methods are urgently needed. Although considerable RBC formulas and indices have been developed since 1973, distinguishing between IDA and TT is still a challenging problem due to the diversity of various anemic populations. To address this problem, we assessed the diagnostic function of 43 different differential formulas in patients with microcytic anemia by using accuracy measures and recommending a new log-based differential formula.

METHODS

The data of 430 pregnant women (229 with TT and 201 with IDA) were enrolled, and 44 formula performances were evaluated with receiver operating characteristic (ROC) analysis.

RESULTS

The newly introduced logarithm-based formula XS-1 performs better than the general discriminant index with sensitivity and specificity of 82.10 and 89.05, which are better than other formulas. In the pregnant population, the Shine and Lal and Roth..SVM. formulas have shown excellent performance, while other formulas showed poorer discriminative abilities in our study than in the original authors.

CONCLUSION

The logarithm-based formula XS-1 can be used to screen thalassemia and iron deficiency anemia during the first trimester. Considering the particularity of pregnancy, medical personnel in different regions should choose a screening formula similar to that of the local region and population when identifying thalassemia in pregnancy. Any formula should be independently verified locally before use. For the convenience of the health care team and experimental scientists, a web-based tool has been established at http://yyy.yiyiy.top/XS-1/ by which users can easily get their desired screening test result without going through the underlying mathematical and computational details.

Red Blood Cell Alloimmunizations in Thalassaemia Patients With Regular Transfusion in China: a Systematic Review and Meta-Analysis

OBJECTIVE

The development of red blood cell alloimmunization intensifies transfusion complication in thalassaemia patients. The purpose of this paper is to evaluate the existing evidence on the prevalence of erythrocyte alloimmunization in China by meta-analysis. We systematically searched cross-sectional studies regarding the alloimmunization of thalassaemia patients with regular blood transfusion in China from year 2000 to May 2021 in the Cochrane library, PubMed, EMBASE, Web of Science, and Chinese databases including CNKI, Wanfang Data, Vip and CBM. Data extraction and quality evaluation of the included studies were performed. Meta-analysis was performed using the DerSimonian and Laird random-effects models with inverse variance weighting. The presence of publication bias was tested by Egger's test, and the methodological quality of each included article was evaluated by the criteria specific to prevalence studies.

RESULTS

A total of 1874 patients and 263 alloantibodies from 11 studies were identified and included in the meta-analysis. The proportion of alloantibodies against antigens belonging to the Rh, MNSs and Kidd systems were as high as 70.3%, 17.9%, and 6.5%, respectively. Meta-analysis showed that the overall prevalence of alloimmunization among transfusion-dependent thalassaemia patients in China is 11.4% (95%CI: 7.2%∼16.3%).

CONCLUSIONS

The characteristics of red blood cell alloimmunization among thalassaemia patients with regular transfusion in China differ greatly from those in other countries. Therefore, transfusion strategies shall be actively adapted in line with thalassaemia patients in China to minimize the risk of alloimmunization.

CRISPR Gene Therapy: A Promising One-Time Therapeutic Approach for Transfusion-Dependent β-Thalassemia—CRISPR-Cas9 Gene Editing for β-Thalassemia

β-Thalassemia is an inherited hematological disorder that results from genetic changes in the β-globin gene, leading to the reduced or absent synthesis of β-globin. For several decades, the only curative treatment option for β-thalassemia has been allogeneic hematopoietic cell transplantation (allo-HCT). Nonetheless, rapid progress in genome modification technologies holds great potential for treating this disease and will soon change the current standard of care for β-thalassemia. For instance, the emergence of the CRISPR/Cas9 genome editing platform has opened the door for precision gene editing and can serve as an effective molecular treatment for a multitude of genetic diseases. Investigational studies were carried out to treat β-thalassemia patients utilizing CRISPR-based CTX001 therapy targeting the fetal hemoglobin silencer BCL11A to restore γ-globin expression in place of deficient β-globin. The results of recently carried out clinical trials provide hope of CTX001 being a promising one-time therapeutic option to treat β-hemoglobinopathies. This review provides an insight into the key scientific steps that led to the development and application of novel CRISPR/Cas9–based gene therapies as a promising therapeutic platform for transfusion-dependent β-thalassemia (TDT). Despite the resulting ethical, moral, and social challenges, CRISPR provides an excellent treatment option against hemoglobin-associated genetic diseases.

Genetic variant of endothelial protein C receptor genes and its serum level in B thalassemic children

BACKGROUND

Due to their chronic hypercoagulable status, thalassemic individuals are at an elevated risk of developing thromboembolic sequence consequences. The goal of the current study is to assesses the EPCR gene polymorphism and soluble EPCR in Egyptian thalassemic children and its role in hypercoagulable state.

RESEARCH DESIGN AND METHODS

Eighty children diagnosed as thalassemia major and 80 healthy youngsters as a control group. The EPCR gene was identified using a restriction fragment length polymerase chain reaction (RFLP PCR). Additionally, we assessed the soluble EPCR levels using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Frequency of 1651C-G EPCR, the GC genotype was strongly related with an increased risk of coagulation (OR = 1.83 (0.64-5.26), P = 0.0.016). In addition, soluble EPCR was considerably higher in patients with thalassemia than in controls, P value <0.001. Our study revealed significance difference between soluble EPCR and different genotypes.

CONCLUSION

Polymorphisms in the EPCR gene and an elevated soluble EPCR level in patients with β-thalassemia major may contribute to these patients' hemostatic derangement in thalassemic Egyptian children.

Third-Generation Sequencing as a New Comprehensive Technology for Identifying Rare α- and β-Globin Gene Variants in Thalassemia Alleles in the Chinese Population

CONTEXT.—

Identification of rare thalassemia variants requires a combination of multiple diagnostic technologies.

OBJECTIVE.—

To investigate a new approach of comprehensive analysis of thalassemia alleles based on third-generation sequencing (TGS) for identification of α- and β-globin gene variants.

DESIGN.—

Enrolled in this study were 70 suspected carriers of rare thalassemia variants. Routine gap-polymerase chain reaction and DNA sequencing were used to detect rare thalassemia variants, and TGS technology was performed to identify α- and β-globin gene variants.

RESULTS.—

Twenty-three cases that carried rare variants in α- and β-globin genes were identified by the routine detection methods. TGS technology yielded a 7.14% (5 of 70) increment of rare α- and β-globin gene variants as compared with the routine methods. Among them, the rare deletional genotype of -THAI was the most common variant. In addition, rare variants of CD15 (G>A) (HBA2:c.46G>A), CD117/118(+TCA) (HBA1:c.354_355insTCA), and β-thalassemia 3.5-kilobase gene deletion were first identified in Fujian Province, China; to the best of our knowledge, this is the second report in the Chinese population. Moreover, HBA1:c.-24C>G, IVS-II-55 (G>T) (HBA1:c.300+55G>T) and hemoglobin (Hb) Maranon (HBA2:c.94A>G) were first identified in the Chinese population. We also identified rare Hb variants of HbC, HbG-Honolulu, Hb Miyashiro, and HbG-Coushatta in this study.

CONCLUSIONS.—

TGS technology can effectively and accurately detect deletional and nondeletional thalassemia variants simultaneously in one experiment. Our study also demonstrated the application value of TGS-based comprehensive analysis of thalassemia alleles in the detection of rare thalassemia gene variants.

Fetal allotransplant recipients are resistant to graft-versus-host disease

In utero hematopoietic cell transplantation (IUHCT) is an experimental treatment for congenital hemoglobinopathies, including Sickle cell disease and thalassemias. One of the principal advantages of IUHCT is the predisposition of the developing fetus toward immunologic tolerance. This allows for engraftment across immune barriers without immunosuppression and, potentially, decreased susceptibility to graft-versus-host disease (GVHD). We demonstrate fetal resistance to GVHD following T cell-replete allogeneic hematopoietic cell transplantation compared with the neonate. We show that this resistance is associated with elevated fetal serum interleukin-10 conducive to the induction of regulatory T cells (Tregs). Finally, we demonstrate that the adoptive transfer of Tregs from IUHCT recipients to neonates uniformly prevents GVHD, recapitulating the predisposition to tolerance observed after fetal allotransplantation. These findings demonstrate fetal resistance to GVHD following hematopoietic cell transplantation and elucidate Tregs as important contributors.

Identification of rare thalassemia variants using third-generation sequencing

Routine PCR, Sanger sequencing, and specially designed GAP-PCR are often used in the genetic analysis of thalassemia, but all these methods have limitations. In this study, we evaluated a new third-generation sequencing-based approach termed comprehensive analysis of thalassemia alleles (CATSA) in subjects with no variants identified by routine PCR, Sanger sequencing, and specially designed GAP-PCR. Hemoglobin testing and routine PCR tests for 23 common variants were performed for 3,033 subjects. Then, Sanger sequencing and specially designed GAP-PCR were performed for a subject with no variants identified by routine PCR, no iron deficiency, and positive hemoglobin testing. Finally, the new CATSA method was conducted for the subjects with no variants identified by Sanger sequencing and specially designed GAP-PCR. In the 49 subjects tested by CATSA, eight subjects had variants identified. Sanger sequencing and independent PCR confirmed the CATSA result. In addition, it is the first time that Hb Lepore was identified in Hunan Province. In total, traditional methods identified variants in 759 of the 3,033 subjects, while CATSA identified additional variants in eight subjects. CATSA showed great advantages compared to the other genetic testing methods.

CRISPR Activator Approaches to Study Endogenous Androglobin Gene Regulation

Androglobin (ADGB), the most recently identified member of the mammalian globin family, is a chimeric protein with an unusual, embedded globin domain that is circularly permutated and exhibits hallmarks of a hexacoordinated heme-binding scheme. Whereas abundant expression of ADGB was initially found to be mainly restricted to cells in the postmeiotic stages of spermatogenesis, more recent RNA-Seq-based expression analysis data revealed that ADGB is detectable in cells carrying motile cilia or flagella. This very tight regulation of ADGB gene expression urges the need for alternative techniques to study endogenous expression in classical mammalian cell models, which do not express ADGB. We describe here the use of CRISPR activation (CRISPRa) technology to induce endogenous ADGB gene expression in HEK293T, MCF-7, and HeLa cells from its promoter and illustrate how this method can be employed to validate putative regulatory DNA elements of ADGB in promoter and enhancer regions.

A MALDI-TOF mass spectrometry-based haemoglobin chain quantification method for rapid screen of thalassaemia

BACKGROUND

Thalassaemia is one of the most common inherited monogenic diseases worldwide with a heavy global health burden. Considering its high prevalence in low and middle-income countries, a cheap, accurate and high-throughput screening test of thalassaemia prior to a more expensive confirmatory diagnostic test is urgently needed.

METHODS

In this study, we constructed a machine learning model based on MALDI-TOF mass spectrometry quantification of haemoglobin chains in blood, and for the first time, evaluated its diagnostic efficacy in 674 thalassaemia (including both asymptomatic carriers and symptomatic patients) and control samples collected in three hospitals. Parameters related to haemoglobin imbalance (α-globin, β-globin, γ-globin, α/β and α-β) were used for feature selection before classification model construction with 8 machine learning methods in cohort 1 and further model efficiency validation in cohort 2.

RESULTS

The logistic regression model with 5 haemoglobin peak features achieved good classification performance in validation cohort 2 (AUC 0.99, 95% CI 0.98-1, sensitivity 98.7%, specificity 95.5%). Furthermore, the logistic regression model with 6 haemoglobin peak features was also constructed to specifically identify β-thalassaemia (AUC 0.94, 95% CI 0.91-0.97, sensitivity 96.5%, specificity 87.8% in validation cohort 2).

CONCLUSIONS

For the first time, we constructed an inexpensive, accurate and high-throughput classification model based on MALDI-TOF mass spectrometry quantification of haemoglobin chains and demonstrated its great potential in rapid screening of thalassaemia in large populations.Key messagesThalassaemia is one of the most common inherited monogenic diseases worldwide with a heavy global health burden.We constructed a machine learning model based on MALDI-TOF mass spectrometry quantification of haemoglobin chains to screen for thalassaemia.

TNF-alpha gene polymorphism and its relation to vitamin D, calcium, alkaline phosphatase and ferritin status in Iraqi beta thalassemia patients

Introduction and Aim: Due to a lack of effective medications, beta-thalassemia is a serious issue in Iraq. Thus, the current investigation aimed to explore the relationship between TNF-alpha gene polymorphism G/A (rs 1800629), Vitamin D (Vit D), Calcium (Ca), alkaline phosphatase (ALP), and ferritin status in Iraqi beta thalassemia major and intermediate patients.   Materials and Methods: Blood samples were collected from 46 patients suffering from thalassemia major (TM) plus 48 patients suffering from thalassemia intermediate (TI) and 48 of apparently healthy volunteers as control group aged 18-60 years, from Ibn Al-Baladi Hospital, Baghdad.   Results: Studies for the distribution of TNF- alpha G/A (rs 1800629) genotype showed that among TM patients and TI patients, the prevalence of the mutant AA genotype (rs 1800629) was higher in TM patients, while in the control group, it was lower.  Similarly, for the wild genotype (GG), the prevalence was highest in control group followed by T1 and TM patients. The frequency of A allele was high in TM patients, while the G allele frequency was more in the control group. Results also showed that the TNF- alpha genotype variations influenced Vitamin D, Calcium, ALP, and ferritin levels in TM and TI patients, wherein the patients with TNF-alpha mutant genotype (AA) were associated with highest levels of ferritin and ALP among all genotypes groups, while the patients of with TNF-alpha wild genotype (GG) were associated with high levels of Vitamin D and Calcium among all genotypes groups.   Conclusion: Patients with at least one copy of (A) allele had a higher risk of TM and TI and there was an association between the heterogeneous (GA) and mutant (AA) genotypes, also presence of (A) allele with status differences of Vit D, Ca, ALP, and ferritin in Iraqi beta thalassemia major and intermediate patients.

Molecular characterization of HBB gene mutations in beta-thalassemia patients of Southern Iraq

Introduction and Aim: Beta-thalassemia is a serious inherited genetic disorder and an increasing health burden globally. Beta -thalassemia is caused by genetic globin abnormalities within the hemoglobin beta (HBB) gene. This study aimed to characterize the HBB gene mutations in beta -thalassemia among southern Iraqi patients.   Materials and Methods: The study included 30 beta -thalassemia patients referred to the Thi-Qar Center for Genetic Diseases, Iraq and 15 control samples from a random group of apparently healthy individuals. Genomic DNA was isolated from blood sample collected from each individual. The DNA was amplified for specific regions of the HBB gene and the amplified products sequenced. The sequences generated were analysed for mutations using sequence analysis tools.   Results: Molecular analysis revealed several mutations in the HBB gene including translocation, deletion and substitution mutations in the population tested positive for the beta -thalassemia trait.   Conclusion:  Thalassemia major is a serious concern in southern Iraq and therefore this study emphasizes a need for complete mutation profiling of the beta -globin gene as a strategy for screening of carriers within the population. Such examinations could be useful in pre-marital genetic counseling and for undertaking prevention and treatment measures.

Fertility preservation for pediatric patients with hemoglobinopathies: Multidisciplinary counseling needed to optimize outcomes

Hemoglobinopathies are autosomal recessive disorders that occur when genetic mutations negatively impact the function of hemoglobin. Common hemoglobinopathies that are clinically significant include sickle cell disease, alpha thalassemia, and beta thalassemia. Advancements in disease-modifying and curative treatments for the common hemoglobinopathies over the past thirty years have led to improvements in patient quality of life and longevity for those who are affected. However, the diseases, their treatments and cures pose infertility risks, making fertility preservation counseling and treatment an important part of the contemporary comprehensive patient care. Sickle cell disease negatively impacts both male and female infertility, primarily by testicular failure and decreased ovarian reserve, respectively. Fertility in both males and females with beta thalassemia major are negatively impacted by iron deposition due to chronic blood transfusions. Hematopoietic stem cell transplant (HSCT) is currently the only curative treatment for SCD and transfusion dependent beta thalassemia. Many of the conditioning regimens for HSCT contain chemotherapeutic agents with known gonadotoxicity and whole-body radiation. Although most clinical studies on toxicity and impact of HSCT on long-term health do not evaluate fertility, gonadal failure is common. Male fertility preservation modalities that exist prior to gonadotoxic treatment include sperm banking for pubertal males and testicular cryopreservation for pre-pubertal boys. For female patients, fertility preservation options include oocyte cryopreservation and ovarian tissue cryopreservation. Oocyte cryopreservation requires controlled ovarian hyperstimulation (COH) with ten to fourteen days of intensive monitoring and medication administration. This is feasible once the patient has undergone menarche. Follicular growth is monitored via transvaginal or transabdominal ultrasound, and hormone levels are monitored through frequent blood work. Oocytes are then harvested via a minimally invasive approach under anesthesia. Complications of COH are more common in patients with hemoglobinopathies. Ovarian hyperstimulation syndrome creates a greater risk to patients with underlying vascular, pulmonary, and renal injury, as they may be less able to tolerate fluids shifts. Thus, it is critical to monitor patients undergoing COH closely with close collaboration between the hematology team and the reproductive endocrinology team. Counseling patients and families about future fertility must take into consideration the patient's disease, treatment history, and planned treatment, acknowledging current knowledge gaps.

RS12574989 and haplotype associated with α/β-chain imbalance and population HbA2 reduction

Determining the associated relationship of genotype and phenomenon would benefit the understanding of disease and renew disease intervention means. 14,518 patients who underwent haemoglobin electrophoresis from June 2020 to December 2020 were enrolled in our study, and additional data including sex, age and routine blood examination results were collected. We focused on individuals with normal red blood cell indices and no common thalassemia pathogenic mutation and selected three groups for the following study: the control group (2.5% ≤ HbA₂ ≤ 3.5%), the HbA₂ under 2.5 group (HbA₂ < 2.5%) and the HbA₂ under 2.4 group (HbA₂ < 2.4%). Four regions of β-globin regulation were sequenced. Statistical analysis was conducted to compare the collected information of the three groups and the genotype distributions in the control group and sequenced group. The HbA₂ under 2.5 group was characterized by a majority of females and lower red blood cell counts and haemoglobin compared with the control group. There were genotypes associated with the grouping as the T of rs12574989 and TTTAGC of the haplotype were significantly increased in the HbA₂ under 2.4 group and CTTAGC was significantly decreased in the HbA₂ under 2.4 group. This study demonstrated that the genotypes of the population associated with HbA₂ were reduced in southern China.

Adapting the ACMG/AMP variant classification framework: A perspective from the ClinGen Hemoglobinopathy Variant Curation Expert Panel

Accurate and consistent interpretation of sequence variants is integral to the delivery of safe and reliable diagnostic genetic services. To standardize the interpretation process, in 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published a joint guideline based on a set of shared standards for the classification of variants in Mendelian diseases. The generality of these standards and their subjective interpretation between laboratories has prompted efforts to reduce discordance of variant classifications, with a focus on the expert specification of the ACMG/AMP guidelines for individual genes or diseases. Herein, we describe our experience as a ClinGen Variant Curation Expert Panel to adapt the ACMG/AMP criteria for the classification of variants in three globin genes (HBB, HBA2, and HBA1) related to recessively inherited hemoglobinopathies, including five evidence categories, as use cases demonstrating the process of specification and the underlying rationale.

Thalassaemia

Thalassaemia is a diverse group of genetic disorders with a worldwide distribution affecting globin chain synthesis. The pathogenesis of thalassaemia lies in the unbalanced globin chain production, leading to ineffective erythropoiesis, increased haemolysis, and deranged iron homoeostasis. The clinical phenotype shows heterogeneity, ranging from close to normal without complications to severe requiring lifelong transfusion support. Conservative treatment with transfusion and iron chelation has transformed the natural history of thalassaemia major into a chronic disease with a prolonged life expectancy, albeit with co-morbidities and substantial disease burden. Curative therapy with allogeneic haematopoietic stem cell transplantation is advocated for suitable patients. The understanding of the pathogenesis of the disease is guiding therapeutic advances. Novel agents have shown efficacy in improving anaemia and transfusion burden, and initial results from gene therapy approaches are promising. Despite scientific developments, worldwide inequality in the access of health resources is a major concern, because most patients live in underserved areas.

Peripheral Blood Erythrocyte Parameters in Β-Thalassemia Minor with Coexistent Iron Deficiency: Comparisons between Iron-Deficient and -Sufficient Carriers

Changes in erythrocyte parameters are well known in both β-thalassemia minor (BTM) and iron deficiency (ID) when either is present alone; however, to our knowledge, there has been no study showing the changes when the two conditions coexist. We herein assessed erythrocyte parameters in BTM with coexistent ID. The BTM cases were divided into two groups based on ferritin levels as ID+ and ID−; the ID+ group was then further divided based on hemoglobin (Hb) levels as iron-deficient carriers with (IDA+) and without (IDA−) anemia. When compared to the ID− group, all parameters were significantly different in the IDA+ group except mean corpuscular volume (MCV) and red blood cells (RBC). All parameters except RBC were significantly different between the IDA+ and IDA− groups. Hb, hematocrit (Hct), MCV, and mean corpuscular hemoglobin (MCH) levels in the IDA− group were found to be lower than in the ID− group. Changes in erythrocyte parameters in iron-deficient carriers are critical in screening for BT, particularly for correct formulation of mathematical algorithms utilized by artificial intelligence programs.

Identification of novel γ-globin inducers among all potential erythroid druggable targets

Human γ-globin is predominantly expressed in fetal liver erythroid cells during gestation from 2 nearly identical genes, HBG1 and HBG2, that are both perinatally silenced. Reactivation of these fetal genes in adult red blood cells can ameliorate many symptoms associated with the inherited β-globinopathies, sickle cell disease, and Cooley anemia. Although promising genetic strategies to reactivate the γ-globin genes to treat these diseases have been explored, there are significant barriers to their effective implementation worldwide; alternatively, pharmacological induction of γ-globin synthesis could readily reach the majority of affected individuals. In this study, we generated a CRISPR knockout library that targeted all erythroid genes for which prospective or actual therapeutic compounds already exist. By probing this library for genes that repress fetal hemoglobin (HbF), we identified several novel, potentially druggable, γ-globin repressors, including VHL and PTEN. We demonstrate that deletion of VHL induces HbF through activation of the HIF1α pathway and that deletion of PTEN induces HbF through AKT pathway stimulation. Finally, we show that small-molecule inhibitors of PTEN and EZH induce HbF in both healthy and β-thalassemic human primary erythroid cells.

Targeting the Hematopoietic Stem Cell Niche in β-Thalassemia and Sickle Cell Disease

In the last decade, research on pathophysiology and therapeutic solutions for β-thalassemia (BThal) and sickle cell disease (SCD) has been mostly focused on the primary erythroid defect, thus neglecting the study of hematopoietic stem cells (HSCs) and bone marrow (BM) microenvironment. The quality and engraftment of HSCs depend on the BM microenvironment, influencing the outcome of HSC transplantation (HSCT) both in allogeneic and in autologous gene therapy settings. In BThal and SCD, the consequences of severe anemia alter erythropoiesis and cause chronic stress in different organs, including the BM. Here, we discuss the recent findings that highlighted multiple alterations of the BM niche in BThal and SCD. We point out the importance of improving our understanding of HSC biology, the status of the BM niche, and their functional crosstalk in these disorders towards the novel concept of combined therapies by not only targeting the genetic defect, but also key players of the HSC–niche interaction in order to improve the clinical outcomes of transplantation.