Hb H disease: clinical course and disease modifiers

Hypoxia favors tumor growth in colorectal cancer in an integrin αDβ1/hemoglobin δ-dependent manner

Low oxygen tension (PO2), characterizes the tissue environment of tumors. The colorectal tumor line Colo205, grown under reduced oxygen tension expresses a novel αDβ1 integrin, which forms a cell surface complex with hemoglobin δ. This resulted in high local affinity for oxygen, which increased cell adhesion as compared with cells grown under normal oxygen tension. Staining with antibodies to the integrin αD polypeptide and hemoglobin δ, and transfection with cDNAs for GFP-hemoglobin δ and mCherry-αD, showed co-localization of αD and hemoglobin δ. Antibodies to αD and β1 integrins, an RGD peptide, and an αDβ1 binding peptide from hemoglobin δ, blocked the αDβ1-hemoglobin interaction and lowered oxygen consumption. Downregulation of integrin αD or hemoglobin δ expression inhibited cell proliferation in hypoxia. The very frequent expression of complexes between αDβ1 and hemoglobin δ on the cell surface offers potential diagnostic and therapeutic targets in colorectal cancer.

Impact of HbE mutation on the clinical severity of HbH disease: A multicentre study from Thailand

Haemoglobin (Hb) H disease and HbH disease with co-inherited HbE mutation are the most prevalent forms of α-thalassaemia in Southeast Asia. Data were limited when comparing clinical phenotypes between these two patient groups. We conducted a Thai multicentre study and enrolled 588 patients [median (IQR) age 13.0 (6.7-20.3) years], including those with deletional HbH disease with (n = 47) and without (n = 187) co-inherited HbE mutation and non-deletional HbH disease with (n = 101) and without (n = 253) co-inherited HbE mutation. Patients with HbH disease with co-inherited HbE mutation suffered more severe manifestations than those without. This observation was more pronounced in patients with non-deletional HbH disease. A greater proportion of patients with non-deletional HbH disease with co-inherited HbE mutation (43.6%) eventually required regular transfusions compared to those without (30.4%, p = 0.019). Among those with non-deletional HbH disease who did not require regular transfusions, Hb levels were lower in patients with co-inherited HbE mutation [8.1 (7.2-8.6) vs. 8.8 (8.2-9.5) g/dL, p < 0.001]. Among patients requiring regular transfusions who underwent splenectomy, 11/12 patients with non-deletional HbH disease stopped transfusion compared with 1/3 in non-deletional HbH disease with co-inherited HbE mutation group (p = 0.024). These findings provide insights for the clinical monitoring and management of HbH disease in the region.

Efficient and in situ correction of hemoglobin Constant Spring mutation by prime editing in human hematopoietic cells

Hemoglobin Constant Spring (Hb CS) is the most common non-deletional and clinically significant α-thalassemic mutation, and it is caused by an anti-termination mutation at the α2-globin gene stop codon. We developed a prime editing strategy for the creation and correction of Hb CS. We showed that prime editing could efficiently introduce Hb CS mutations in both human erythroblast cell lines (an average frequency of 32%) and primary hematopoietic stem and progenitor cells (HSPCs) from healthy donors (an average frequency of 27%). By targeting the established Hb CS homozygous erythroblasts, we achieved an average frequency of 32% in situ correction without selection. Notably, prime editing corrected the Hb CS mutation to wild type at an average frequency of 21% in HSPCs from three patients with hemoglobin H Constant Spring (HCS). Erythrocytes that differentiated from prime-edited erythroblasts or HSPCs exhibited a significant reduction in the amount of αCS-globin chains. Insertions and deletions on HBA2 locus and Cas9-dependent DNA off-target editing were detected with relatively low frequency after prime editing. Our findings showed that prime editing can successfully correct Hb CS in erythroblasts and patient HSPCs, which provides proof of principle for its therapeutic potential in HCS.

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.

Disease burden, management strategies, and unmet needs in α-thalassemia due to hemoglobin H disease

Alpha-thalassemia is an inherited blood disorder caused by impaired α-globin chain production, leading to anemia and other complications. Hemoglobin H (HbH) disease is caused by a combination of mutations generally affecting the expression of three of four α-globin alleles; disease severity is highly heterogeneous, largely driven by genotype. Notably, non-deletional mutations cause a greater degree of ineffective erythropoiesis and hemolysis, higher transfusion burden, and increased complication risks versus deletional mutations. There are limited treatment options for HbH disease, and effective therapies are needed. This review discusses the pathophysiology of HbH disease, current management strategies, unmet needs, and emerging treatment options.

Hemoglobinopathies in the Neonate

Hemoglobinopathies in neonates constitute a group of disorders influenced by genetic mutations in the human globin genes. They are often broadly categorized into quantitative defects or qualitative defects, though they are not mutually exclusive. In quantitative defects, the mutation causes insufficient production of a normal globin chain, which can range from no production to mild deficiency. These are typically referred to as thalassemias. In qualitative defects, the structure of the hemoglobin is altered. The most common structural hemoglobinopathy is sickle cell disease. During fetal development, distinct globin chains are synthesized, which undergo a progressive switch to adult globin chains perinatally. This affects the timing of the clinical presentation of these disorders and thus, our ability to diagnose them. In this review, we focus on the epidemiology, genetic causes, clinical presentation, and general overview and management of common hemoglobin disorders that may be encountered in the neonatal period.

Erythropoiesis and Gene Expression Analysis in Erythroid Progenitor Cells Derived from Patients with Hemoglobin H/Constant Spring Disease

Hemoglobin H/Constant Spring (Hb H/CS) disease represents a form of non-deletional Hb H disease characterized by chronic hemolytic anemia that ranges from moderate to severe and may lead to transfusion-dependent thalassemia. To study the underlying mechanisms of this disease, we conducted an analysis of erythropoiesis and gene expression in erythroid progenitor cells derived from CD34+ hematopoietic stem/progenitor cells from patients with Hb H/CS disease and normal controls. Twelve patients with Hb H/CS disease and five normal controls were enrolled. Peripheral blood samples were collected to isolate CD34+ hematopoietic stem/progenitor cells for the analysis of cell proliferation and differentiation. Six samples from patients with Hb H/CS disease and three controls were subsequently studied for gene expression by next generation sequencing analysis. Erythroid progenitor cells derived from patients with Hb H/CS disease exhibited a trend towards increased rates of erythroid proliferation and decreased cell viability compared to those from controls. Moreover, erythroid progenitor cells derived from patients with Hb H/CS disease demonstrated delayed terminal differentiation. Gene expression profiling revealed elevated levels of genes encoding molecular chaperones, including the heat shock protein genes (HSPs) and the chaperonin containing TCP-1 subunit genes (CCTs) in the Hb H/CS disease group. In summary, erythroid progenitor cells derived from patients with Hb H/CS disease exhibit a trend towards heightened erythroid proliferation, diminished cell viability, and delayed terminal differentiation. Additionally, the increased expression of genes encoding molecular chaperones was observed, providing information on potential underlying pathophysiological mechanisms.

De-novo ATR-16 syndrome associated with inherited hemoglobin Evanston causing HbH phenotype: a rare occurrence

Abnormality of three α-globin genes, either deletion or point mutation results in symptomatic Hemoglobin H (HbH) phenotype. Most of such cases of α-globin defects are inherited from the parents, de-novo cases are exceedingly rare. Herein, a case of HbH is reported where the proband inherited one α-globin gene with a point mutation (αEvanston) from the mother. This was associated with large de-novo deletion of chromosome 16p13.3 resulting in α-thalassemia and mental retardation (ATR-16) syndrome. This deletion also encompassed two α-globin genes from chromosome 16, eventually leading to --/ααEvanston genotype, explaining the clinical presentation of the proband. The challenges in screening of such cases and confirming the molecular diagnosis along with the mode of inheritance has been discussed.

Hemoglobin Balkh, a Novel Mutation in Codon 132 of α2-Globin Gene [α132(H15) (+T) or HBA2:C.396dup (p.Val134fs)]: A Case Report and Insight into the Pathophysiology

We report a novel mutation on α2-globin gene leading to an elongated α-chain. This novel frameshift mutation was detected in a 13-year-old boy from Balkh province, Afghanistan. DNA analysis identified an insertion of thymine (T) at codon 132 [HBA2:c.396dup (p.Val134fs)]. We named the novel hemoglobin variant 'Hemoglobin Balkh' after the geographic location from which the patient originated. This novel variant was found in association with α3.7 kb α-globin gene deletion, suggesting a compound heterozygous state that contributes to the patient's clinical presentation.

The First Thai Case of Nondeletional HbH Disease Caused by Compound Heterozygosity for α-Thalassemia-1 Chiang Rai (--CR) Type Deletion with Hb Constant Spring

Hemoglobin (Hb) H disease presents a wide range of clinical phenotypes, from asymptomatic to severe forms, depending on significant genetic heterogeneity. This is the first report of clinical and hematological features of the nondeletional HbH disease caused by --CR/αCSα. A baby was born to a father and a mother with --CR and αCSα carriers, respectively. She had severe symptomatic hypochromic microcytic anemia at 2 months of age with Hb 7.8 g/dL, packed cell volume (PCV) 0.27 L/L, mean corpuscular volume (MCV) 64.3 fL, and mean corpuscular Hb (MCH) 18.3 pg. The Hb analysis using capillary electrophoresis (CE) showed Hb Bart's, HbH, and Hb CS peaks at 17.1%, 2.2%, and 1.6%, respectively. A better understanding of a patient's clinical and hematological features with --CR/αCSα is useful for hemoglobinopathy counseling for the national thalassemia controlling program.

A rare hemoglobinopathy duo: Hb Adana×Hb SEA in a 1-year-old patient - a case report and a brief literature review

Introduction and importance

Alpha thalassemia, resulting from nondeletional mutations, typically presents a more severe clinical manifestation compared to deletional mutations. Severe outcomes, such as hydrops fetalis, are associated with two specific nondeletional mutations. Therefore, DNA-based investigation is crucial for suspected carriers exhibiting subtle hematological abnormalities to facilitate proper diagnosis and effective family counseling.

Case presentation

In this report, the authors describe a phenotypically normal 1-year-old girl with a rare and unique alpha-thalassemia genotype due to the presence of Hb Adana, a nondeletional alpha-chain mutation compounded with Hb SEA, an alpha-globin gene deletion.

Clinical discussion

Mutations determine the clinical manifestations of alpha-thalassemia. DNA testing is recommended for suspected carriers with relatively small hematological abnormalities, for precise diagnosis and family counseling. To provide clinicians with a reference for diagnostic assessment, the authors established a genotype-phenotype correlations based on reported cases of Hb Adana following an exhaustive literature review. Being interested in determining which ethnicities and genotypes are associated with a higher risk of complications, including hydrops fetalis and transfusion dependence, the authors formalized a diagnostic evaluation guide and a guide for early screening to improve outcomes.

Conclusion

Precise genetic evaluation is important for the diagnosis of alpha thalassemia. Hematologists play a critical role in managing these disorders, understanding genotype-phenotype correlations, and highlighting the significance of genetic counseling for high-risk patients. Extensive studies on these various genophenotypes are required to improve the diagnosis and prognosis of such medical conditions and advocate preventative strategies.

Interplay between α-thalassemia and β-hemoglobinopathies: Translating genotype-phenotype relationships into therapies

α-Thalassemia represents one of the most important genetic modulators of β-hemoglobinopathies. During this last decade, the ongoing interest in characterizing genotype-phenotype relationships has yielded incredible insights into α-globin gene regulation and its impact on β-hemoglobinopathies. In this review, we provide a holistic update on α-globin gene expression stemming from DNA to RNA to protein, as well as epigenetic mechanisms that can impact gene expression and potentially influence phenotypic outcomes. Here, we highlight defined α-globin targeted strategies and rationalize the use of distinct molecular targets based on the restoration of balanced α/β-like globin chain synthesis. Considering the therapies that either increase β-globin synthesis or reactivate γ-globin gene expression, the modulation of α-globin chains as a disease modifier for β-hemoglobinopathies still remains largely uncharted in clinical studies.

Αlpha-thalassemia: A practical overview

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and β globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

Hematological Profile of Hb Adana Among High School Students in Northeast Peninsular Malaysia

Background Hb Adana is a non-deletional alpha (α)-thalassaemia variant resulting from mutations in α1- or α2-globin codon 59 (αCD59), leading to the production of unstable α-globin. Clinical manifestations can vary from silent carrier status to dependence on blood transfusions, hepatosplenomegaly, skeletal deformities, and spinal cord compression. Despite the significance of Hb Adana inheritance, studying this variant poses challenges due to the scarcity of molecular tests and the potential for routine diagnoses to be overlooked. This study aims to investigate the prevalence of Hb Adana among local high school students and assess the hematological parameters and hemoglobin analysis of Hb Adana in Malaysia. Methodology This retrospective study analyzed 13,721 blood samples collected from high school students participating in Malaysia's National Thalassaemia Screening Program at Hospital Raja Perempuan Zainab II (HRPZ II). Deletional α-thalassaemia was detected using multiplex gap-polymerase chain reaction (PCR), while common non-deletional α-thalassaemia was identified using multiplex amplification refractory mutation system (ARMS) PCR. Data were extracted from the HRPZ II database for analysis. Results Among the participants, 2327 individuals were found to have either common deletional (n=1037, 44.6%) or non-deletional (n=1290, 55.4%) α-thalassaemia. Hb Constant Spring was the most prevalent non-deletional α-thalassaemia, accounting for 53.03% of cases. Thirty-one participants (1.33%) exhibited αCD59α/αα, and one (0.04%) had αCD59α/-α3.7. Among the 32 subjects with Hb Adana, 87.5% were Malay, and 12.5% were Orang Asli. Additionally, seven cases of HbE/Hb Adana co-inheritance were identified. Hemoglobin levels in heterozygous Hb Adana individuals ranged from mild anemia to normal, between 95 g/L and 153 g/L. Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were approximately 73 fL and 23 pg, respectively. Conclusion This study delineates the distribution of α-thalassaemia mutation patterns among high school students in Kelantan, Northeast Peninsular Malaysia. Our findings indicate that Hb Adana is rare in our region and co-inheritance with an α-gene deletion results in α+-thalassaemia and with HbE, α0-thalassaemia. All heterozygous Hb Adana individuals exhibited low MCVs and MCHs.

Pyruvate kinase activators: targeting red cell metabolism in thalassemia

Thalassemia is an inherited red blood cell disorder whereby the qualitative and/or quantitative imbalance in α- to β-globin ratio results in hemolysis and ineffective erythropoiesis. Oxidative stress, from the precipitated excess globin and free iron, is a major factor that drives hemolysis and ineffective erythropoiesis. Pyruvate kinase activity and adenosine triphosphate availability are reduced due to the overwhelmed cellular antioxidant system from the excessive oxidative stress. Mitapivat, a pyruvate kinase activator in development as a treatment for thalassemia, was shown to increase hemoglobin and reduce hemolysis in a small phase 2 single-arm trial of patients with α- and β-thalassemia. The ongoing phase 3 studies with mitapivat and the phase 2 study with etavopivat will examine the role of pyruvate kinase activators as disease modifying agents in thalassemia.

Direct cord blood LAMP colorimetric phenol red assay for detecting α0-thalassemia (SEA deletion); the validation and post-natal screening in Thailand

Post-natal or newborn screening for thalassemia and hemoglobinopathies is useful for genetic counseling and managing thalassemia in children. We characterized thalassemia genotypes in newborns from the eastern part of Thailand. The results demonstrated a high heterogeneity of thalassemia and hemoglobinopathies with seventeen genotypes. We focused on α0- thalassemia (Southeast Asian [SEA] deletion) in this study. We developed and validated the loop-mediated isothermal amplification (LAMP) colorimetric assay for detecting α0- thalassemia (SEA deletion) using simple direct cord blood sampling compared to genomic DNA. A total of 160 cord blood samples were evaluated with the LAMP assay. The sensitivity and specificity of the LAMP colorimetric assay for α0-thalassemia (SEA deletion) using direct cord blood showed 100% (6/6 x 100) and 98.05% (151/154 x 100) whereas, genomic DNA showed 100% (6/6 x 100) and 100% (154/154 x 100), respectively. Moreover, we demonstrated other simple screening tools for α0-thalassemia with %Hb Bart's, MCV, and MCH values and found that these parameters were not diagnostic in our samples. The direct cord blood with colorimetric LAMP assay is simple, rapid, and does not require a post-LAMP step compared to conventional PCR. These techniques could be applied in post-natal or large population screening for α0-thalassemia (SEA deletion). Finally, this could support early prevention of complications, early management, genetic counseling for α-thalassemia disease in children, or a long-term prevention and control program of severe thalassemia in Thailand.

Hemoglobin profile and molecular characteristics of the complex interaction of hemoglobin Doi-Saket [α9(A7) asn > lys, HBA2:c.30C > a], a novel α2α1 hybrid globin variant, with hemoglobin E [β26(B8) Glu > lys, HBB:c.79G > A] and deletional α+-thalassemia in a Thai family

BACKGROUND

An increasing number of α-hemoglobin (Hb) variants is causing various clinical symptoms; therefore, accurate identification of these Hb variants is important.

OBJECTIVE

This study aimed to describe the molecular and hematological characteristics of novel Hb Doi-Saket that gives rise to a typical α+-thalassemia phenotype in carriers with and without other hemoglobinopathies.

MATERIALS AND METHODS

Biological samples from a proband and his family members were analyzed. Hematological profiles were analyzed using a standard automated cell counter. Hb was analyzed by capillary electrophoresis and high-performance liquid chromatography. Mutations and globin haplotype were identified by DNA analysis. Novel diagnostic tools based on allele-specific polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism were developed.

RESULTS

Hb analysis showed a major abnormal Hb fraction, moving slower than HbA, and a minor Hb fraction alongside HbA2 in the proband, his father, and son. DNA analysis of the α-globin gene identified the -α3.7 deletion and in cis the C > A mutation on codon 9 of the α2α1 gene, corresponding to Hb Doi-Saket [α9(A7) Asn > Lys]. This mutation could be identified using newly developed allele-specific PCR-based assays. The Hb Doi-Saket al.lele was significantly associated with haplotype [- + M + + 0 -]. Interaction of αDoi-Saket with βE globin chains led to a new Hb variant (HbE Doi-Saket). Phenotypic expression was clinically silent in heterozygotes and might present slight microcytosis.

CONCLUSIONS

Hb Doi-Saket emphasizes a great diversity present in α-globin gene. The mutation in this family from Thailand was linked to -α3.7 and caused mild microcytosis in the carriers. The combination of this variant with deletions in α genes might cause a severe clinical phenotype. Different methods of separation can provide useful information in diagnosis, and a complete molecular approach is needed for confirmation before considering patient management.

Molecular analysis and clinical significance of hemoglobin Quong Sze in Huizhou city, Southern China

OBJECTIVE

Hemoglobin Quong Sze (Hb QS) is one of the most common non-deletional α-thalassemia (α-thal), which is prevalent in the Southern Chinese population. However, there are still few comprehensive researches on the molecular characterization of Hb QS. So it is important to find out appropriate diagnosis and characterization of Hb QS carrier for genetic counseling.

MATERIALS AND METHODS

A hematological screening including hematological indices and hemoglobin analysis was performed in 113,400 individuals from Huizhou city, Southern China. Then, suspected thalassemia carriers were detected by a suspension-array system and DNA sequencing for α- and β-thal.

RESULTS

In our study, we identified 521 subjects who were Hb QS carriers, including fourteen different genotypes. Among them, 445 Hb QS heterozygotes showed a decrease in the mean corpuscular hemoglobin (MCH), 16 compound heterozygotes for Hb QS/α+-thal presented mild thalassemia, 28 Hb QS in combination with --SEA/αα manifested as Hb H disease, varying clinical symptoms from only moderate anemia to severe anemia and requiring blood transfusion, and 29 double heterozygotes for Hb QS and β-thal behaved as β-thal trait. The mean corpuscular volume (MCV) and MCH were significantly reduced and no Hb H peak could be detected in one patient with Hb H-Hb QS and β-thal. Meanwhile, we identified two homozygous Hb QS carriers, who showed mild to moderate anemia and increased Hb A2 level but negative results from a sequencing analysis for the first time. Additionally, Comparison of hematological parameters among the major four genotype groups showed significant differences in most box-whisker plots.

CONCLUSION

People who originated from Huizhou city showed many genotypes and diversity in the clinical manifestations of Hb QS carriers. This study enlarges the mutation spectrum of α-thal and emphasizes that reliable detection of the gene mutations is important for genetic counseling. It also strengthens the prevention and control of thalassemia.

Hemoglobin H Disease and Growth: A Comparative Study of DHbH and NDHbH Patients

Background

Hemoglobin H disease (HbH), a hemoglobinopathy resulting from abnormal alpha globin genes, is classified into two categories: deletional HbH (DHbH) and non-deletional HbH (NDHbH). The alpha-mutation genotypes exhibit a range of clinical anemias, which differentially impact patient growth.

Objectives

This retrospective study assessed the growth of HbH patients at Siriraj Hospital, Mahidol University.

Methods

Patients diagnosed with HbH between January 2005 and April 2021 were analyzed using growth standard scores of the Thai Society for Pediatric Endocrinology (2022 version) and BMI-for-age Z scores of the World Health Organization. Growth failure was defined as a patient's height for age exceeding two standard deviations below the mean.

Results

Of the 145 HbH patients, 75 (51.7%) had NDHbH, with --SEA/αCSα being the most common genotype (70 patients; 93.3%). The mean baseline hemoglobin level was significantly lower in NDHbH patients than in DHbH patients (8.16 ± 0.93 g/dL vs. 9.51 ± 0.68 g/dL; P < 0.001). Splenomegaly and growth failure prevalences were higher in NDHbH patients (37.3% vs. 0%, with P < 0.001, and 22.7% vs. 8.6%, with P = 0.020, respectively). Multivariable analysis revealed splenomegaly > 3 cm was associated with growth failure (OR = 4.28; 95% CI, 1.19-15.39; P = 0.026).

Conclusions

NDHbH patients exhibited lower hemoglobin levels and more pronounced splenomegaly than DHbH patients. Growth failure can occur in both HbH types but appears more prevalent in NDHbH. Close monitoring of growth velocity is essential, and early treatment interventions may be required to prevent growth failure.

A novel gain-of-function PIP4K2A mutation elevates the expression of β-globin and aggravates the severity of α-thalassemia

Haemoglobin H (Hb H) disease (intermediate status of α-thalassemia) shows marked phenotypic variability from asymptomatic to severe anaemia. Apart from the combined β-thalassemia allele ameliorating clinical severity, reports of genetic modifier genes affecting the phenotype of Hb H disease are scarce which bring inconvenience to precise diagnosis and genetic counselling of the patients. Here, we present a novel mutation (c.948C>A, p.S316R) in the PIP4K2A gene in a female Hb H disease patient who displayed moderate anaemia and a relatively high Hb H level. Haematological analysis in her family members revealed that individuals carrying this mutation have upregulated β-globin expression, leading to a more imbalanced β/α-globin ratio and more Hb H inclusion bodies in peripheral red blood cells. According to functional experiments, the mutant PIP4K2A protein exhibits enhanced protein stability, increased kinase activity and a stronger regulatory effect on downstream proteins, suggesting a gain-of-function mutation. Moreover, introduction of the S316R mutation into HUDEP-2 cells increased expression of β-globin, further inhibiting erythroid differentiation and terminal enucleation. Thus, the S316R mutation is a novel genetic factor associated with β-globin expression, and the PIP4K2A gene is a new potential modifier gene affecting the α-thalassemia phenotype.

Effective screening of hemoglobin Constant Spring and hemoglobin Paksé with several forms of α- and β-thalassemia in an area with a high prevalence and heterogeneity of thalassemia using capillary electrophoresis

Background and aims

We aimed to evaluate the efficiency of identification and quantification of hemoglobin (Hb) Constant Spring (CS) and Hb Paksé by capillary electrophoresis (CE).

Materials and methods

Blood samples collected from 2057 patients were used for identifying and quantifying Hb by CE. Molecular analysis of α- and β-thalassemia, Hb CS, and Hb Paksé was performed.

Results

Hb CS and Hb Paksé were identified in 573 samples (27.86%) with diverse genotypes. Thirty-eight samples (6.6%) showed no Hb CS peak. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of Hb CS by CE were 93.37, 95.96, 89.92, 97.40, and 95.24%, respectively. The amount of Hb CS in those carrying Hb CS was 0.2-6.5% which showed an increasing trend according to the number of defective α-globin genes, in contrast to Hb A2 levels, which decreased. Hb CS level ≥1.0% accurately excluded heterozygotes and that of ≥2.0% could identify homozygotes.

Conclusion

CE has the high potential for identifying and quantifying Hb CS and Hb Paksé, especially in an area with a high prevalence of thalassemia. Hb CS levels can be used as a potential marker to distinguish the genotype of individuals carrying Hb CS.

The Clinical Phenotypes of Alpha Thalassemia

Clinical manifestations of α-thalassemia range from no symptoms to severe transfusion-dependent anemia. Alpha thalassemia trait is deletion of 1 to 2 α-globin genes, whereas α-thalassemia major (ATM; Barts hydrops fetalis) is the deletion all 4 α genes. All other genotypes of intermediate severity are categorized as HbH disease, a vastly heterogenous group. Clinical spectrum is classified as mild, moderate, and severe by symptoms and need for intervention. Anemia in prenatal period may be fatal without intrauterine transfusions. New therapies to modify HbH disease or provide cure for ATM are under development.

Severity scoring system to guide transfusion management in pediatric non-deletional HbH

BACKGROUND

Hemoglobin (Hb) H is generally recognized as mild thalassemia, despite its actual phenotypic diversity. A disease severity scoring system to guide initiation of regular transfusion among severely affected pediatric patients has not previously been reported.

METHODS

Patients with HbH were classified into transfusion-dependent thalassemia (TDT) and non-transfusion-dependent thalassemia (NTDT) as a surrogate for disease severity. Alpha-globin genotypes and relevant clinical parameters associated with TDT were identified. Univariate and multiple logistic regression analyses were performed to yield the most suitable severity scoring system.

RESULTS

From 246 patients with a median age of 14.3 (interquartile range 9.9-18.4) years initially enrolled into the study, the chance of having severe disease and developing TDT was remarkable only among patients with non-deletional HbH, for whom the scoring system was developed. Univariate and multiple logistic regression analyses resulted in three retained parameters associated with TDT, β-coefficients of which were used to develop the score. The final scoring system comprised age at diagnosis <2 years (score = 1), spleen size ≥3 cm (score = 1) and Hb at steady-state <7 (score = 4) or 7-8 g/dL (score = 3). A cutoff score ≥4 was associated with severe disease likely requiring regular transfusion (sensitivity 89.3%, specificity 81.4%), given regular transfusion resulted in maintained growth. The scoring system was validated in the second cohort of 77 non-deletional HbH, from which comparable sensitivity and specificity were obtained.

CONCLUSION

The newly developed scoring system was practical and helpful to highlight severely affected pediatric non-deletional HbH patients with potential needs of regular transfusion. This can be used as a guide for optimal treatment and disease monitoring in the future.

An analysis of the distribution and spectrum of alpha thalassemia mutations in Rasht City, North of Iran

Background

Alpha thalassemia is one of the most common hereditary hemoglobin disorders worldwide, particularly in the Middle East, including Iran. Therefore, determining the spectrum and distribution of alpha thalassemia mutation is a fundamental component of preventive approaches and management strategies.

Methods

The present study reviews the genetic testing and blood laboratory results of 455 candidates eligible for marriage who were suspected of being thalassemia carriers and on whom genetic testing was performed from 21 March 2013 to 31 December 2020 in Rasht City.

Results

A total of 114 (25.05%) alpha thalassemia cases were identified. Fifteen different alpha mutations were found. The most common mutation among the study population was -α^3.7 deletion in 55 patients (48.24%), followed by Hb Constant Spring (C.S) in 21 patients (18.42%) and poly A2 in 16 (14.03%). Also, most of the patients were silent carriers. The deletion type of mutation was much more common than non-deletion mutations.

Conclusion

Our study reveals genetic heterogeneity and alpha thalassemia diversity among the Rasht City population. We expect that these findings will help guide premarital screening and genetic counseling, prenatal diagnosis of thalassemia, preventive strategy development, as well as a compilation of the alpha thalassemia catalog in Guilan province.

Novel Decision Tool for More Severe α-Thalassemia Genotypes Screening with Functional Loss of Two or More α-Globin Genes: A Diagnostic Test Study

After the exclusion of iron deficiency and β-thalassemia, molecular research for α-thalassemia is recommended to investigate microcytic anemia. Aiming to suggest more efficiently the molecular analysis for individuals with a greater chance of having a symptomatic form of the disease, we have developed and validated a new decision tool to predict the presence of two or more deletions of α-thalassemia, increasing considerably the pre-test probability. The model was created using the variables: the percentage of HbA₂, serum ferritin and mean corpuscular volume standardized by age. The model was trained in 134 patients and validated in 160 randomly selected patients from the total sample. We used Youden's index applied to the ROC curve methodology to establish the optimal odds ratio (OR) cut-off for the presence of two or more α-globin gene deletions. Using the OR cut-off of 0.4, the model's negative predictive value (NPV) was 96.8%; the cut-off point accuracy was 85.4%; and the molecular analysis pre-test probability increased from 25.9% to 65.4% after the use of the proposed model. This tool aims to assist the physician in deciding when to perform molecular studies for the diagnosis of α-thalassemia. The model is useful in places with few financial health resources.

DeepThal: A Deep Learning-Based Framework for the Large-Scale Prediction of the α+-Thalassemia Trait Using Red Blood Cell Parameters

Objectives: To develop a machine learning (ML)-based framework using red blood cell (RBC) parameters for the prediction of the α+-thalassemia trait (α+-thal trait) and to compare the diagnostic performance with a conventional method using a single RBC parameter or a combination of RBC parameters. Methods: A retrospective study was conducted on possible couples at risk for fetus with hemoglobin H (Hb H disease). Subjects with molecularly confirmed normal status (not thalassemia), α+-thal trait, and two-allele α-thalassemia mutation were included. Clinical parameters (age and gender) and RBC parameters (Hb, Hct, MCV, MCH, MCHC, RDW, and RBC count) obtained from their antenatal thalassemia screen were retrieved and analyzed using a machine learning (ML)-based framework and a conventional method. The performance of α+-thal trait prediction was evaluated. Results: In total, 594 cases (female/male: 330/264, mean age: 29.7 ± 6.6 years) were included in the analysis. There were 229 normal controls, 160 cases with the α+-thalassemia trait, and 205 cases in the two-allele α-thalassemia mutation category, respectively. The ML-derived model improved the diagnostic performance, giving a sensitivity of 80% and specificity of 81%. The experimental results indicated that DeepThal achieved a better performance compared with other ML-based methods in terms of the independent test dataset, with an accuracy of 80.77%, sensitivity of 70.59%, and the Matthews correlation coefficient (MCC) of 0.608. Of all the red blood cell parameters, MCH < 28.95 pg as a single parameter had the highest performance in predicting the α+-thal trait with the AUC of 0.857 and 95% CI of 0.816−0.899. The combination model derived from the binary logistic regression analysis exhibited improved performance with the AUC of 0.868 and 95% CI of 0.830−0.906, giving a sensitivity of 80.1% and specificity of 75.1%. Conclusions: The performance of DeepThal in terms of the independent test dataset is sufficient to demonstrate that DeepThal is capable of accurately predicting the α+-thal trait. It is anticipated that DeepThal will be a useful tool for the scientific community in the large-scale prediction of the α+-thal trait.

In Vitro Study of Ineffective Erythropoiesis in Thalassemia: Diverse Intrinsic Pathophysiological Features of Erythroid Cells Derived from Various Thalassemia Syndromes

Defective hemoglobin production and ineffective erythropoiesis contribute to the pathophysiology of thalassemia syndromes. Previous studies in the field of erythropoiesis mainly focused on the severe forms of thalassemia, such as β-thalassemia major, while mechanisms underlying the pathogenesis of other thalassemia syndromes remain largely unexplored. The current study aimed to investigate the intrinsic pathophysiological properties of erythroid cells derived from the most common forms of thalassemia diseases, including α-thalassemia (hemoglobin H and hemoglobin H-Constant Spring diseases) and β-thalassemia (homozygous β⁰-thalassemia and β⁰-thalassemia/hemoglobin E diseases), under an identical in vitro erythroid culture system. Cell proliferation capacity, differentiation velocity, cell death, as well as globin synthesis and the expression levels of erythropoiesis modifying factors were determined. Accelerated expansion was found in erythroblast cells derived from all types of thalassemia, with the highest degree in β⁰-thalassemia/hemoglobin E. Likewise, all types of thalassemia showed limited erythroid cell differentiation, but each of them manifested varying degrees of erythroid maturation arrest corresponding with the clinical severity. Robust induction of HSP70 transcripts, an erythroid maturation-related factor, was found in both α- and β-thalassemia erythroid cells. Increased cell death was distinctly present only in homozygous β⁰-thalassemia erythroblasts and associated with the up-regulation of pro-apoptotic (Caspase 9, BAD, and MTCH1) genes and down-regulation of the anti-apoptotic BCL-XL gene.

Detection of hemoglobin H disease by long molecule sequencing

Background

Hemoglobin H (Hb H) disease is a moderate‐to‐severe form of α‐thalassemia (α‐thal), and parts of patients may require intermittent transfusion therapy, especially during intercurrent illness. However, rare Hb H diseases remain undetected using routine methods being outside of the testing scope. In this study, we present an approach to detecting Hb H disease by long molecule sequencing (LMS).

Methods

A total of 206 known genotype samples were collected and carried to blind detected by LMS on the PacBio Sequel platform. Circular consensus sequencing reads were aligned to the hg19 reference genome using Free‐Bayes finished LMS. LMS accuracy would be compared with routine methods, including Gap‐PCR and PCR‐Reverse dot blot hybridization (PCR–RDB).

Results

The assay could detect carriers of both deletion and point mutations. It had an overall accuracy of 100% when compared with routine methods. In addition, LMS detected six mutations based on routine methods and corrected three case results. Hb H diseases were identified using LMS, whether a common or rare genotype, a deletion or non‐deletion genotype. However, two cases of Hb H disease were misdiagnosed using routine methods.

Conclusions

Long molecule sequencing can be suggested as a rapid and reliable assay to detect probable carriers of hemoglobinopathies. LMS accurately identified the common and rare genotypes of Hb H disease.

Clinical and genetic characteristics of hemoglobin H disease in Iran

Hemoglobin H (Hb H) disease is a subtype of α-thalassemia caused by deletional and/or non-deletional mutations in three alpha-globin genes in which the various genotypes determine the disease severity. This study was aimed to investigate the frequency of alpha gene mutations and genotypes and their correlation with hematological and clinical characteristics in Iran. Among 202 patients diagnosed with Hb H disease through a national study in Iran according to standard methods, we had access to the hematologic and clinical findings and genetic data of 101 patients in whom genetic study was performed. Genomic DNA from peripheral blood was extracted and analyzed for identification of α-globin gene mutations using Multiplex Gap Polymerase Chain Reaction, Reverse Hybridization Assay, and finally Direct DNA Sequencing method. Twenty-one different mutations and thirty genotypes were detected in 101 patients with Hb H disease. In total, 39 patients (38.6%) were deletional and 62 patients (61.4%) were non-deletional type of the disease. The _--^MED mutation was highly prevalent in almost half of the patients (56.4%). Among various genotypes, -^MED/-a^3.7 (29.7%) and -α^20.5/-α^5NT (6.9%) were the most prevalent genotypes found in the studied group. Patients with non-deletional type presented with more severe hematological and clinical findings. Hb H percentage and serum ferritin levels were significantly higher in non-deletional patients in comparison to the deletional group (p < 0.05). 12 (11.9%) and 40 (39.6%) out of 101 patients were on regular and occasional transfusions, respectively. 83% of those with regular transfusion belonged to the non-deletional group. Among transfusion-dependent patients, -^MED/α^CSα and α^20.5/-α^5NT were the most common genotypes. In this study, two patients with -α^20.5/α^CSα and -^MED/α^-5NT genotypes experienced thrombotic events. This study indicated that although non-deletional genotypes of Hb H disease were responsible for more clinical severity of the disease, due to the presence of severe phenotypes even in deletional types, no definite correlation was found between genotype and phenotype.

Anemia in the pediatric patient

The World Health Organization estimates that approximately a quarter of the world's population suffers from anemia, including almost half of preschool-age children. Globally, iron deficiency anemia is the most common cause of anemia. Other important causes of anemia in children are hemoglobinopathies, infection, and other chronic diseases. Anemia is associated with increased morbidity, including neurologic complications, increased risk of low birth weight, infection, and heart failure, as well as increased mortality. When approaching a child with anemia, detailed historical information, particularly diet, environmental exposures, and family history, often yield important clues to the diagnosis. Dysmorphic features on physical examination may indicate syndromic causes of anemia. Diagnostic testing involves a stepwise approach utilizing various laboratory techniques. The increasing availability of genetic testing is providing new mechanistic insights into inherited anemias and allowing diagnosis in many previously undiagnosed cases. Population-based approaches are being taken to address nutritional anemias. Novel pharmacologic agents and advances in gene therapy-based therapeutics have the potential to ameliorate anemia-associated disease and provide treatment strategies even in the most difficult and complex cases.

Molecular Heterogeneity of Hb H Disease in India

Alpha thalassemia is an autosomal recessive disorder caused by large deletions and/or point mutations in the α- globin genes. Hemoglobin H (Hb H) disease is most frequently due to deletion of three of the four α globin genes associated with variable clinical severity depending on the genotype. There are few reports on Hb H disease in Indians where genotyping has been done and we have reviewed the molecular and clinical heterogeneity of these cases. An electronic search for relevant articles was conducted using two journal databases, i.e., PubMed and Science Direct using the key words “Hb H Disease”, “Hemoglobin H”, “α-thalassemia”, “mutations”, “molecular heterogeneity”, “case reports” and “India”. This review was performed based on preferred reporting items for the systematic review and meta-analysis protocols (PRISMA-P) guidelines. The molecular spectrum of Hb H disease in Indians includes the most common [-α3.7, -α4.2, --SA, Poly A (AATAAA→AATA--), Hb Sallanches], rare [--SEA, --MED, IVS 1nt 1 (G→A), Hb Koya Dora, Hb Sun Prairie], very rare [Hb Iberia, Hb Seal Rock, Hb Zürich-Albisrieden] and novel [Codon 76 (+T) and --Kol] α-globin gene mutations inherited largely as compound heterozygotes with considerable clinical variability. The molecular diagnosis of Hb H disease is important for genetic counseling and management.

Outcomes of pregnancies complicated by haemoglobin H-constant spring and deletional haemoglobin H disease: A retrospective cohort study

The objective of the study was to compare the maternal and foetal outcomes of pregnancies complicated by Hb H-constant spring (HbH-CS) disease/deletional HbH (HbH-del) disease and low-risk pregnancies. A retrospective cohort research was undertaken on singleton pregnancies with Hb H-CS and Hb H-del diseases. The controls were randomly selected with a control-to-case ratio of 10:1. A total of 55 cases of HbH-CS disease, 231 cases of HbH-del disease and 2860 controls were compared. The mean gestational age at delivery and birthweight were significantly lower in the HbH-CS group than in the HbH-del and control groups. The clinical course of Hb H-CS was more severe than that of HbH-del disease. The rates of preterm birth, foetal growth restriction and low birthweight were significantly increased in the HbH-CS and Hb H-del groups. These rates were significantly greater in the HbH-CS group than in the H-del group. The maternal outcomes were not significantly different among the three groups. In conclusion, pregnancy worsens the course of HbH disease, more noticeably in HbH-CS disease. Hb H disease significantly increases the risk of adverse foetal outcomes, more noticeably in the HbH-CS group. Pregnancy is relatively safe for women with HbH disease.

Genotype-phenotype correlation in patients with deletional and nondeletional mutations of Hb H disease in Southwest of Iran

We studied the alpha-globin gene genotypes, hematologic values, and transfusion-dependence of patients with Hb H disease. Molecular characterization of alpha-thalassemia was performed. We identified 120 patients with Hb H disease. Of these patients, 35 (29.16%) had deletional form of Hb H disease, and 85 (70.83%) had different form of non-deletional Hb H disease. The most frequently observed Hb H genotypes were --^Med/-α^3.7 in 33 patients (27.5%), α^CD19(-G) α^/αCD19(-G) α in 25 cases (20.83%), α^polyA2α/α^polyA2α in 15 (12.5%), and α^polyA1α/α^polyA1α in 13 (10.83%) respectively. The probability of receiving at least one transfusion blood in deletional form was observed in 3 of 35 (8.57%) patients which just seen in 3 of 33 (9%) patients with --^Med/-α^3.7 genotype. This form was also observed in 8 of 85 (9.4%) patients in non-deletional Hb H diseases which five of them had Med deletion in compound with alpha globin point mutations. Nondeletional Hb H disease was more severe than deletional Hb H disease requiring more blood transfusions. We can recommend that Med deletion in compound with alpha-globin point mutations, polyA1 and constant spring in homozygous form needs to be taken into consideration when offering counseling to high-risk couples.

[Regulation effect of siRNA on β-globin in erythrocytes of hemoglobin H disease]

Objective: To investigate the regulatory effect of targeted siRNA on β-globin in erythroid cells cultured by targeted differentiation in vitro and provide new theoretical support for gene therapy for hemoglobin H (HbH) disease. Methods: Based on the β-globin gene expression results, the optimal siRNA sequence and its effective action dose were screened in erythroid cells, and the effect of the effective dose of the optimal siRNA on the regulation of β-globin expression and apoptosis in erythroid cells was examined. The effective dose of the optimal siRNA was applied to erythroid cells with HbH disease. The effects of transfected siRNAs on red line cells with HbH disease were comprehensively evaluated by measuring the expression of β-globin, reactive oxygen species (ROS) , and apoptosis rates. Results: Within 96 hours after transfection, siRNA2 significantly downregulated β-globin expression in in vitro cultured erythroid cells, but not α-globin. siRNA silencing effect and duration of effect were dose-dependent. siRNA2 downregulated β-globin expression, reduced intracellular ROS production, and decreased apoptosis rate in erythroid cells with HbH disease. Conclusion: Targeted siRNAs can downregulate β-globin expression, reduce intracellular ROS production, and downregulate apoptosis rate in erythroid cells with HbH disease.

Thalassemias: From gene to therapy

Thalassemias (α, β, γ, δ, δβ, and εγδβ) are the most common genetic disorders worldwide and constitute a heterogeneous group of hereditary diseases characterized by the deficient synthesis of one or more hemoglobin (Hb) chain(s). This leads to the accumulation of unstable non-thalassemic Hb chains, which precipitate and cause intramedullary destruction of erythroid precursors and premature lysis of red blood cells (RBC) in the peripheral blood. Non-thalassemic Hbs display high oxygen affinity and no cooperativity. Thalassemias result from many different genetic and molecular defects leading to either severe or clinically silent hematologic phenotypes. Thalassemias α and β are particularly diffused in the regions spanning from the Mediterranean basin through the Middle East, Indian subcontinent, Burma, Southeast Asia, Melanesia, and the Pacific Islands, whereas δβ-thalassemia is prevalent in some Mediterranean regions including Italy, Greece, and Turkey. Although in the world thalassemia and malaria areas overlap apparently, the RBC protection against malaria parasites is openly debated. Here, we provide an overview of the historical, geographic, genetic, structural, and molecular pathophysiological aspects of thalassemias. Moreover, attention has been paid to molecular and epigenetic pathways regulating globin gene expression and globin switching. Challenges of conventional standard treatments, including RBC transfusions and iron chelation therapy, splenectomy and hematopoietic stem cell transplantation from normal donors are reported. Finally, the progress made by rapidly evolving fields of gene therapy and gene editing strategies, already in pre-clinical and clinical evaluation, and future challenges as novel curative treatments for thalassemia are discussed.

Direct PCR assays without DNA extraction for rapid detection of hemoglobin Constant Spring and Pakse' genes: application for carrier screening and prenatal diagnosis

Hemoglobin Constant Spring (Hb CS) and Hb Pakse' (PS) are the common non-deletional α⁺-thalassemia found in Thailand. These two variants can cause severe thalassemia syndromes, especially in fetus and neonate. Molecular diagnosis is the only confirmatory method because Hb CS and Hb PS are usually missed by routine screening and Hb analysis. Therefore, we aimed to develop rapid direct PCR for the diagnosis of Hb CS and PS genes. Multiplex direct PCR assays for identifying the Hb CS and PS genes in whole blood (WB) and amniotic fluid (AF) specimens were developed. The assays were firstly validated on 290 unrelated whole blood specimens. Hb CS and PS carriers were identified in 67 (23.1%) and 6 (2.1%) cases, respectively. A 100% concordant result as compared to routine PCR assay was observed. The direct PCR assays have been applied successfully for prenatal diagnosis in two families. The result showed that the fetuses were affected by homozygous Hb CS and compound heterozygous Hb CS/Hb PS. Accurate prenatal diagnosis of these families was observed using the newly developed assays. These assays should be applicable in routine thalassemia diagnostics as well as in the large-scale screening of Hb CS and PS in the region.

PTD-mediated delivery of α-globin chain into Κ-562 erythroleukemia cells and α-thalassemic (HBH) patients' RBCs ex vivo in the frame of Protein Replacement Therapy

Background

α-Thalassemia, a congenital hemoglobinopathy, is characterized by deficiency and/or reduced levels of α-globin chains in serious forms of α-thalassemia (HbH disease/Hb Bart’s). This research work deals with a Protein Replacement Therapy approach in order to manage α-thalassemia manifestations, caused by the excess of β-globin chain into HbH RBCs. The main goal was to produce the recombinant human α-globin chain in fusion with TAT, a Protein Transduction Domain, to ex vivo deliver it into HbH patients RBCs, to replace the endogenous missing α-globin chain.

Results

Cloning of the α-globin coding sequence, fused to the nucleotide sequence of TAT peptide was conducted and the human recombinant fusion proteins, 10xHis-Xa_SITE-α-globin-HA and 10xHis-Xa_SITE-TAT-α-globin-HA were produced. The ability of human recombinant 10xHis-Xa_SITE-α-globin-HA to interact in vitro with the previously produced 10xHis-Xa_SITE-TAT-β-globin-HA and form α-/β-globin heterodimers, was assessed and confirmed by size exclusion chromatography. The recombinant 10xHis-Xa_SITE-TAT-α-globin-HA was successfully delivered into human proerythroid K-562 cells, during the preliminary transduction evaluation experiments. Finally, the recombinant, TAT-fused α-globin was successfully transduced into RBCs, derived from HbH patients and reduced the formation of HbH-Inclusion Bodies, known to contain harmful β₄-globin chain tetramers.

Conclusions

Our data confirm the successful ex vivo transduction of recombinant α-globin chains in HbH RBCs to replace the missing a-globin chain and reduce the HbH-inclusion bodies, seen in α-thalassemias. These findings broaden the possibility of applying a Protein Replacement Therapy approach to module sever forms of α-thalassemia, using recombinant α-globin chains, through PTD technology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40709-021-00148-3.

Successful Implementation of Newborn Screening for Hemoglobin Disorders in the Philippines

The Philippine newborn bloodspot screening (NBS) program began in 1996 with 24 hospitals and was formalized by legislation in 2004. The NBS panel was recently expanded to include a number of additional hereditary congenital conditions. Expertise and experiences from other NBS programs already screening for hemoglobinopathies were essential to its successful integration into the ongoing dried bloodspot NBS program in the Philippines. Building on clinical experiences and population data from Filipinos born in California, USA, hemoglobinopathies (including thalassemias) were selected for inclusion in the expanded screening panel. Hemoglobinopathy NBS, using high performance liquid chromatography, was implemented in a stepwise manner into the seven regional NBS screening laboratories. A central university laboratory provides confirmatory testing using both capillary electrophoresis and molecular methodologies. NBS results indicating carriers are followed up with educational fact sheets, while results of presumptive disease are referred for confirmatory testing and follow-up with a hematologist. Long-term care is provided through newborn screening continuity clinics across the country. Hemoglobinopathy NBS is now included in the national insurance package and screening uptake continues to increase nationally, exceeding 90% of all newborns in 7400+ hospitals and birthing centers nationwide prior to the COVID-19 pandemic.

First Report of Nondeletional Hb H Disease Caused by an α2-Globin Gene Mutation: HBA2: c.184A>T

We report a rare mutation, HBA2: c.184A>T on the α2-globin gene, detected in a Chinese proband who presented with Hb H disease and a mild anemia. This frameshift mutation results in a premature termination of translation at position 61 of the α2-globin gene. Carriers of this mutation showed a borderline microcytic hypochromia. Our study indicates the importance of screening nondeletional α-thalassemia (α-thal) in areas with a particularly high prevalence of thalassemia such as in Southern China, especially for couples with one partner carrying an α⁰-thal deletion.

Association of hemoglobin H (HbH) disease with hemoglobin A1c and glycated albumin in diabetic and non-diabetic patients

OBJECTIVES

Hemoglobin A1c (HbA1c) and glycated albumin (GA) are glycemic control status indicators in patients with diabetes mellitus. Hemoglobin H (HbH) disease is a moderately severe form of α-thalassemia. Here we examine the usefulness of HbA1c and GA in monitoring glycemic control in patients with HbH disease.

METHODS

HbA1c, GA, and an oral glucose tolerance test were performed in 85 patients with HbH disease and 130 healthy adults. HbA1c was measured using five methods, including two systems based on cation-exchange high-performance liquid chromatography (Variant II Turbo 2.0 and Bio-Rad D100), a capillary zone electrophoresis method (Capillarys 3 TERA), a boronate affinity HPLC method (Premier Hb9210), and an immunoassay (Cobas c501).

RESULTS

Significant lower levels of HbA1c were observed in patients with HbH disease than in healthy adults. In contrast, GA showed no statistically significant differences between participants with and without HbH disease. A considerable number of diabetic patients with HbH disease would be missed if using HbA1c as a diagnostic criterion for diabetes mellitus.

CONCLUSIONS

GA but not HbA1c is suitable for monitoring glycemic control in patients with HbH disease that can modify the discriminative ability of HbA1c for diagnosing diabetes.

Hb Bart's Hydrops Fetalis Syndrome and Hb H Disease Caused by Deletional Chiang Rai (- -CR) α0-Thalassemia in Two Unrelated Thai Families

α⁰-Thalassemia (α⁰-thal) Chiang Rai (- -^CR; NC_000016.10: g.144215_188843del) was identified as a novel 44.6 kb deletional type of α-thalassemia (α-thal), removing all α-like globin genes. However, little is known about the deleterious effects of this genetic disorder, particularly when it is combined with other types of thalassemia. We performed molecular analysis of the - -^CR deletion using gap-polymerase chain reaction (gap-PCR) in two independent families residing in Phayao and Chiang Mai, Thailand, with an unknown causative mutation for Hb Bart's hydrops fetalis syndrome and Hb H disease. Five out of seven individuals were diagnosed to be heterozygous for the - -^CR deletion. Of these, two also carried Hb H disease with compound heterozygosities for - -^CR and -α^3.7 (rightward) deletions. However, hematological parameters of the - -^CR carriers displayed microcytic hypochromic anemia that is comparable to other α⁰-thal traits. Although the prevalence of - -^CR has never been elucidated in a specific population, our study demonstrated that genotyping for - -^CR might be considered as an additional investigation for unexplained Hb Bart's hydrops fetal syndrome and Hb H disease.

A Rare Case of Hb H Disease and Systemic Lupus Erythematosus

Anemia is common in patients with systemic lupus erythematosus (SLE). The association between thalassemia and SLE is rare. In this study, we report the first patient who was found to have a severe hemolytic anemia caused by combination of SLE and Hb H disease. The patient had a more severe presentation in the hematological system. Our case indicates that for a patient who was diagnosed with SLE and developed deterioration in her hematological cell lines, investigation of other possible coexisting causes would be warranted.

Hb Athens-Georgia (beta 40(C6) Arg > Lys, HBB:c.122G > A) with a single α-globin gene (Hb H disease) in a Thai family: molecular, hematological, and diagnostic aspects

Interaction of structural hemoglobin (Hb) variants with α- or β-globin defects are occasional in Southeast Asia. Herein we provide the first description of Hb Athens-Georgia (Hb A-Ga) in association with deletional Hb H disease, a novel combination previously undescribed in the population. Hematological, Hb and DNA analysis, and β-globin haplotype analyses were performed in seven participants from one ethnic Thai family. Hemoglobin analysis by capillary electrophoresis revealed an abnormal Hb fraction in the proband, his father and grandmother (I-2). DNA sequencing revealed that the G > A substitution at codon 40 of the β-globin gene was identical to the Hb A-Ga (HBB:c.122G > A). Interestingly, α-thal-1 (SEA deletion) and α-thal-2 (-α^3.7 deletion) were identified in the proband resulting in Hb H disease, while α-thal-1 was identified in the father, and no α-thal was observed in I-2. Hematological analysis indicated that the proband (β^A-Ga/β^A, -^SEA/-α^3.7) had moderate anemia and was markedly hypochromic with microcytic red blood cells (RBCs). The father (β^A-Ga/β^A, -^SEA/αα) presented mild microcytic anemia, while normal hematology was observed in the I-2 who was heterozygous for Hb Athens-Georgia (β^A-Ga/β^A, αα/αα). The relative level of Hb A-Ga was distinctly reduced according to the degree of α-globin defects. The developed allele-specific PCR method can successfully be used for confirmation of Hb A-Ga. The Thai Hb A-Ga allele associated with a β-haplotype [+ - - - - - +]. These findings were in accordance with the previous conclusion that this variant is a non-pathological β-Hb variant.

Association of Hb Shenyang [α26(B7)Ala→Glu, GCG>GAG, HBA2: c.80C>A (or HBA1)] with Several Types of α-Thalassemia in Thailand

Hb Shenyang [α26(B7)Ala→Glu, HBA2: c.80C>A (or HBA1)] is a rare α chain variant. Its genotype-phenotype relationship and origin have not been described in Thailand before. Three Thai subjects (P1-P3) carrying this variant were studied. Hemoglobin (Hb) analysis was performed by capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) as well as molecular characterization using appropriate polymerase chain reaction (PCR) techniques and DNA sequencing. Hemoglobin analysis by HPLC revealed fast-moving abnormal peaks at a retention time (RT) of 1.59-1.62 min., while CE revealed a fast-moving abnormal Hb at zone 12 and ahead of Hb A₂ in three subjects. DNA analysis revealed a C>A transition at codon 26 of the α2-globin gene glutamic acid to replace alanine, corresponding to Hb Shenyang. The Southeast Asian [- -^SEA α-thalassemia-1 (α-thal-1)] deletion was also identified in P1 and his mother, while Hb Constant Spring (Hb CS, HBA2: c.427T > C) was identified in P2. The Hb Shenyang concentration measured by CE revealed 5.1-17.2% heterozygosity with normal red blood cell (RBC) parameters. The α haplotype [+ - S + - + -] [S signifies the inter ζ hypervariable region (HVR)] was associated with the Thai Hb Shenyang. The genotype-phenotype relationship indicates Hb Shenyang is likely a non pathological Hb variant that has neither dramatic clinical symptoms nor hematological anomalies. A simple multiplex allele-specific PCR for rapid diagnosis of Hb Shenyang has been developed.

Alpha thalassemia genotypes in Kuwait

Background

The frequency of the alpha thalassemia trait is approximately 40% in the Kuwaiti population, but there has been no comprehensive study of the prevalent alleles. This is a report of patients who were referred for molecular diagnosis over a 20-year period.

Methods

This is a retrospective study of the α-globin genotypes obtained in the Hemoglobin Research Laboratory of the Department of Pediatrics, Kuwait University from 1994 to 2015. Genotyping was performed by a combination of PCR, allele-specific oligonucleotide hybridization and reverse dot blot hybridization (Vienna Lab Strip Assay).

Results

Four hundred samples were characterized and analyzed from individuals aged < 1 month to 80 years, with a median of 6 years from 283 unrelated families. Most (90.8%) were Kuwaiti nationals. The commonest genotype was homozygosity for the polyadenylation-1 mutation (α^PA-1α/α ^PA-1α) in 33.3% of the samples, followed by heterozygosity (αα/α ^PA-1α) for the same mutation in 32.3%. PA-1 was therefore the most frequent allele (0.59). The frequency of the α⁰ (−-^MED) allele was 0.017. Rare alleles that were found in very low frequencies included α⁰ (−-^FIL) in a Filipino child, Hb Constant Spring, Hb Adana, and Hb Icaria.

Conclusion

There is a wide variety of alpha thalassemia alleles among Kuwaitis, but nondeletional PA-1 is by far the most common cause of the moderate to severe HbH (β4 tetramer) disease phenotype. The α⁰ (−^MED) allele is also encountered, which has implications for premarital counseling, especially for the possibility of having babies with alpha thalassemia major (Barts hydrops fetalis).

α-Thalassemia Intermedia Results from Interactions of Unstable Hb Prato [α31(B12)Arg→Ser (HBA1 or HBA2 c.96G>T or C)] with the α-Thalassemia-1 [- -SEA (Southeast Asian)] Deletion in Thailand

The clinical consequences of many abnormal hemoglobins (Hbs) interacting with α- or β-thalassemia (α- or β-thal) or other hemoglobinopathies have not been described. We evaluated a 75-year-old Thai woman and her 45-year-old daughter. Hematological data was obtained on an automated cell counter. Hemoglobin (Hb) analysis was carried out using high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) assays. Mutations and globin haplotypes were identified by appropriated DNA techniques. The proband presented with moderate anemia and inclusion bodies in most of the red blood cells (RBCs), while altered RBC parameters were absent in her daughter. Hemoglobin analysis showed an abnormal Hb peak only in the proband. DNA analysis identified a G>T substitution at codon 31 of the α1-globin gene, corresponding to Hb Prato [α31(B12)Arg→Ser (HBA1 or HBA2 c.96G>T or C)] in both subjects. The α-thal-1 [- -^SEA (Southeast Asian)] deletion was also identified in the proband, but not in her daughter. These mutations could be identified using newly developed allele-specific polymerase chain reaction (ASPCR) assays. The α haplotypic analysis demonstrated the Thai Hb Prato allele was associated with haplotype [+ - S + - + -] [the S represents the inter ζ hypervariable region (HVR)]. The combination of the unstable Hb Prato with α-thal-1 result in α-thal intermedia (α-TI) phenotypes. A simple DNA method is essential for detection, and a haplotypic α-globin gene cluster are presented.

Molecular spectrum of Hb H disease and characterization of rare deletional α-thalassemia found in Thailand

Hb H diseases with the clinical features of thalassemia are found in many parts of the world, including Southeast Asia and southern China. There are limitations in molecular data from the population of Thailand, which includes multiple ethnic groups. Here, we characterized the molecular basis of the disease among a large cohort from this region. A total of 479 unrelated Thai patients with Hb H disease were studied. Mutations of the α-globin gene were characterized by conventional gap-PCR and rare genotypes were identified by MLPA analysis and direct DNA sequencing. The molecular characterization showed five common Hb H genotypes (472/479; 98.54%), including three deletional types (-^SEA/-α^3.7; n = 312), (-^SEA/-α^4.2; n = 26), (-^THAI/-α^3.7; n = 1) and two non-deletional types (-^SEA/α^CSα; n = 131), (-^SEA/α^Pakséα; n = 2). Herein, we firstly report a rare genotype of Hb H disease with (-^SA/-α^3.7; n = 1) that has not been documented in Thailand, and rare genotypes related to (-^SEA/-α^16.6; n = 1), and (-^SEA/α^QSα; n = 3) as well. The remaining two cases could not be characterized. The hematological parameters demonstrated that the clinical phenotype of non-deletional Hb H diseases is more severe than the deletional type of α⁺-thalassemia. The molecular spectrum of α-thalassemia is useful for prevention and thalassemia control and genetic counseling for couples at risk in this region.