The molecular spectrum and distribution of haemoglobinopathies in Cyprus: a 20-year retrospective study

The Clinical and Laboratory Profiles of a Deletional α2-Globin Gene Polyadenylation Signal Sequence (AATAAA > AATA--) [HBA2:c.*93_*94delAA]: The Malaysian Experience

Poly A (AATAAA > AATA--) [HBA2:c.*93_*94delAA] is a rare α-variant reported in our population. It is caused by 2 bp deletion (--AA) in the α2 poly A sequence, leading to a significant α-thalassaemia phenotype. Background/Objectives: This study describes the haematological parameters, phenotype, and genotype characteristics of AATA(--AA) in the Malaysian population. Methods: The study was carried out on 17 177 cases referred to the Institute for Medical Research, Malaysia, for further diagnosis of α-thalassaemia in a five-year period. Alpha-Gap and ARMS-PCR were performed to detect common α-thalassaemia, followed by HBA1 and HBA2 genes sequencing and multiplex ligation-dependent probe amplification (MLPA). Haematological parameters among various groups with the AATA(--AA) allele were presented in this study. Results: Thirty-two patients with AATA(--AA) displaying an α-thalassaemia-like phenotype were analysed. They comprised 22 (68.75%) AATA(--AA) carriers, 2 (6.25%) compounds with 3.7 deletion, 2 (6.25%) compounds with --SEA deletion, 1 (3.12%) AATA(--AA) homozygote, and 3 (9.37%) compounds of Hb Adana, Hb CS, and Hb Pakse with co-inheritance Hb E, respectively. Most of the patients with AATA(--AA) compounds with the α-variant exhibited a significant phenotype between moderate to severe thalassaemia, especially cases with compound α-AAα/αAdanaα. Conclusions: AATA(--AA) is a significant pathogenic variant that should be diagnosed to prevent significant thalassaemia phenotype or transfusion-dependent thalassaemia.

Non-Invasive Determination of the Paternal Inheritance in Pregnancies at Risk for β-Thalassaemia by Analyzing Cell-Free Fetal DNA Using Targeted Next-Generation Sequencing

Non-invasive prenatal testing (NIPT) has been widely adopted for the screening of chromosomal abnormalities; however, its adoption for monogenic disorders, such as β-thalassaemia, has proven challenging. Haemoglobinopathies are the most common monogenic disorders globally, with β-thalassaemia being particularly prevalent in Cyprus. This study introduces a non-invasive prenatal haplotyping (NIPH) assay for β-thalassaemia, utilizing cell-free DNA (cfDNA) from maternal plasma. The assay determines paternal inheritance by analyzing highly heterozygous single-nucleotide variants (SNVs) in the β-globin gene cluster. To identify highly heterozygous SNVs in the population, 96 randomly selected samples were processed using Illumina DNA-prep NGS chemistry. A custom, high-density NGS genotyping panel, named HAPLONID, was designed with 169 SNVs, including 15 common pathogenic ones. The AmpliSeq for Illumina assay was then applied to cfDNA to evaluate the panel's efficiency in performing NIPT for β-thalassaemia. Analysis revealed 219 highly polymorphic SNVs, and the sequencing of 17 families confirmed successful paternal allele determination. The NIPH assay demonstrated 100% success in diagnostic interpretation. This study achieved the advancement of an integrated NGS-NIPT assay for β-thalassaemia, bringing it one step closer to being a diagnostic assay and thereby enabling a reduction in the number of risky invasive prenatal sampling procedures in Cyprus and elsewhere.

Carrier rate of thalassemia among 25,910 high school students in Shaoguan area, China

OBJECTIVES

As one of the most common hereditary diseases, thalassemia affects a large number of people in China. The aim of this study was to investigate the feasibility of a method based on next-generation sequencing (NGS) for screening of thalassemia carriers among high school students in the Shaoguan area.

MATERIALS AND METHODS

The NGS-based method was performed using 25,910 high school students recruited from 38 schools. The screening yield was systematically analyzed. Before screening, a lecture on how the disease is inherited, the symptoms of thalassemia, and how to prevent it was given to 28,780 students.

RESULTS

Implying successful delivery of information on the disease, 90.03% (25,910 of 28,780) of the students agreed to join this program for thalassemia screening. A thalassemia carrier rate of 15.99% (4144 of 25,910) was found. Also, 69 rare genotypes (28 of α-thalassemia and 41 of β-thalassemia) and 9 novel variants were identified.

CONCLUSIONS

This NGS-based method provided a feasible platform for high school population thalassemia screening. Combined with a clinical follow-up strategy, it could help eventually to prevent the births of affected children.

Incidence Trends of Inherited Anemias at the Global, Regional, and National Levels Over Three Decades

Inherited anemia continues to pose a significant public health concern on a global scale, owing to its extensive geographical prevalence, substantial patient population, and profound ramifications. Here, we investigated detailed information on inherited anemias (including thalassemias, thalassemias trait, sickle cell disease, sickle cell trait, G6PD deficiency, and G6PD trait) for the period 1990-2019 from the Global Burden of Disease study. Over the course of three decades, there has been a persistent rise in the incidence of inherited anemias worldwide, culminating in a total of 44,896,026 incident cases in 2019. However, the prevalence of inherited anemias has exhibited a consistent downward trend over successive years. Significantly, these inherited anemias primarily impact females, exhibiting a male-to-female ratio of 1:1.88. Among males, the most prevalent inherited anemia is G6PD deficiency, whereas G6PD trait prevails among females. The incidence rates of inherited anemias and their temporal trend exhibited significant variations across different regions, with Central Sub-Saharan Africa displaying the highest incidence rates and Central Latin America experiencing the most substantial decline. The findings of this study suggest a significant correlation between the Socio-Demographic index (SDI) and incidence rates of inherited anemias, particularly in regions with lower SDI levels such as Africa and South Asia. These results contribute valuable insights for the analysis of global trends in the burden of inherited anemias.

Global distribution of β-thalassemia mutations: An update

One excellent illustration of how a single gene abnormality may result in a spectrum of disease incidence is the incredible phenotypic variety of β-thalassemia, which spans from severe anemia and transfusion needs to an utterly asymptomatic sickness. However, genetic causes of β-thalassemia and how the anemia's severity might be altered at various stages in its pathophysiology have been well investigated. There are currently known to be more than 350 mutations that cause genetic disease. However only 20 β thalassemia mutations account for more than 80% of the β thalassemia mutation across the globe due to phenomenon of geographical clustering where each population has a few common mutations together with a varying number of rare ones. Due to migration of the population, the spectrum of thalassemia mutation in changing from time to time. In this review, efforts are made to collate β globin gene mutations in different countries and populations.

Unravelling the Complexity of the +33 C>G [HBB:c.-18C>G] Variant in Beta Thalassemia

The +33 C>G variant [NM_000518.5(HBB):c.-18C>G] in the 5' untranslated region (UTR) of the β-globin gene is described in the literature as both mild and silent, while it causes a phenotype of thalassemia intermedia in the presence of a severe β-thalassemia allele. Despite its potential clinical significance, the determination of its pathogenicity according to established standards requires a greater number of published cases and co-segregation evidence than what is currently available. The present study provides an extensive phenotypic characterization of +33 C>G using 26 heterozygous and 11 compound heterozygous novel cases detected in Cyprus and employs computational predictors (CADD, RegulomeDB) to better understand its impact on clinical severity. Genotype identification of globin gene variants, including α- and δ-thalassemia determinants, and rs7482144 (XmnI) was carried out using Sanger sequencing, gap-PCR, and restriction enzyme digestion methods. The heterozygous state of +33 C>G had a silent phenotype without apparent microcytosis or hypochromia, while compound heterozygosity with a β+ or β0 allele had a spectrum of clinical phenotypes. Awareness of the +33 C>G is required across Mediterranean populations where β-thalassemia is frequent, particularly in Cyprus, with significant relevance in population screening and fetal diagnostic applications.

Incidence Trends of Inherited Anemias at the Global, Regional, and National Levels Over Three Decades

Inherited anemia continues to pose a significant public health concern on a global scale, owing to its extensive geographical prevalence, substantial patient population, and profound ramifications. Here, we investigated detailed information on inherited anemias (including thalassemias, thalassemias trait, sickle cell disease, sickle cell trait, G6PD deficiency, and G6PD trait) for the period 1990–2019 from the Global Burden of Disease study. Over the course of three decades, there has been a persistent rise in the incidence of inherited anemias worldwide, culminating in a total of 44,896,026 incident cases in 2019. However, the prevalence of inherited anemias has exhibited a consistent downward trend over successive years. Significantly, these inherited anemias primarily impact females, exhibiting a male-to-female ratio of 1:1.88. Among males, the most prevalent inherited anemia is G6PD deficiency, whereas G6PD trait prevails among females. The incidence rates of inherited anemias and their temporal trend exhibited significant variations across different regions, with Central Sub-Saharan Africa displaying the highest incidence rates and Central Latin America experiencing the most substantial decline. The findings of this study suggest a significant correlation between the Socio-Demographic index (SDI) and incidence rates of inherited anemias, particularly in regions with lower SDI levels such as Africa and South Asia. These results contribute valuable insights for the analysis of global trends in the burden of inherited anemias.

Molecular characterisation of Hb Akron [β52 (D3) Asp→Val] combined with thalassaemia in a Chinese family

AIMS

Hb Akron (HBB:c.158A>T) is a rare β-chain variant and many characteristics about its clinical features still remain unclear. In this study, we aimed to explore the molecular and haematological characterisations of previously undescribed states for Hb Akron associated with different forms of thalassaemia.

METHODS

Haematology and genetic analysis were performed in 9 members from a Chinese Zhuang ethnic family.

RESULTS

Hb Akron in various combinations with β0-thalassaemia and α0-thalassaemia were identified and characterised. Simple heterozygote for Hb Akron is asymptomatic, while the compound heterozygotes of Hb Akron associated with the β0-thalassaemia mutation generates a more severe haematological phenotype than Hb Akron or β0-thalassaemia mutation seen in isolation. The specific peak of Hb Akron appears at Zone D (195-225 s) in the state of heterozygote and compound heterozygote on haemoglobin capillary electrophoresis device, and the reduction of Hb Akron level in heterozygotes is proportional to the degree of α-globin gene deficiency.

CONCLUSIONS

We have for the first time described the genetic and haematological characteristics of Hb Akron combined with different thalassaemia mutations, which will provide useful information for genetic counselling and prenatal diagnostic service of this mutation in a population with high prevalence of thalassaemia.

The Outcomes of Patients with Haemoglobin Disorders in Cyprus: A Joined Report of the Thalassaemia International Federation and the Nicosia and Paphos Thalassaemia Centres (State Health Services Organisation)

Haemoglobinopathies, including thalassaemias and sickle-cell syndromes, are demanding, lifelong conditions that pose a significant burden to patients, families, and healthcare systems. Despite the therapeutic advances and the resulting improvements in prognosis accomplished in past decades, these patients still face important challenges, including suboptimal access to quality care in areas with developing economies, changing epidemiology due to massive migration flows, an evolving clinical spectrum due to ageing in well-treated patients, and limited access to novel high-cost therapies. We herein describe the organization of healthcare services for haemoglobinopathies in Cyprus—with particular focus on beta-thalassaemia, the most prevalent condition in this region—along with selected patient outcomes. This report aims at underscoring the fact that nationally funded and well-coordinated prevention and care programmes for chronic and complex conditions, such as haemoglobinopathies, with active involvement from patient organizations lead to effective disease control and excellent outcomes in survival, quality of life, social adaptation, and public health savings, and allow timely and effective responses to emerging crises, such as the COVID-19 pandemic. The Cyprus paradigm could therefore serve as a blueprint for the organization or adaptation of haemoglobinopathy programs in other countries since these disorders are still widely occurring.

A New Mutation, Hb A2-Canakkale [δ10(A7)Ala→Val; HBD: c.32C>T], and Other Well-Known δ Variants Identified in a Selected Cohort with Low Hb A2 Levels

Hemoglobinopathies are the most common single-gene disorders, and β-thalassemia (β-thal) imposes a tremendous health burden on Turkey. Thus, premarital carrier screening is obligatory in Turkey, as it is in some other countries. As a result of this mandatory procedure, at routine clinical checkups, many individuals who had undergone premarital screening but did not have any clinical symptoms and/or hematological findings, have compulsorily been required to undergo further evaluation due to abnormal levels of hemoglobin (Hb) fractions (Hb A, Hb A₂ and Hb F). Many consequences, such as mutations in unrelated gene(s) or someone's nutritional status, have been reported to affect the Hb fractions levels. In the present study, we aimed to determine whether HBD has a molecular causative role in patients with low Hb A₂ levels (below 1.8%). The study was conducted with 20 individuals with low Hb A₂ levels who had applied to our outpatient clinic. All DNA samples were analyzed for the HBD gene. Nineteen of the 20 subjects were diagnosed to carry a mutation with one of four different δ-globin variants. Three of them had been described previously [Hb A₂-Yialousa (HBD: c.82G>T), Hb A₂-Bornova (HBD: c.350G>C) and Hb A₂-Yokoshima (HBD: c.77G>A)]. The novel [δ10(A7)Ala→Val, HBD: c.32C>T] mutation was defined as a new δ variant and reported to the HbVar database as Hb A₂-Canakkale. In conclusion, the molecular characterization of Hb A₂ low levels has been suggested to be significant for a definite diagnosis and counseling.

Direct Chromosomal Phasing: An Easy and Fast Approach for Broadening Prenatal Diagnostic Applicability

The assignment of alleles to haplotypes in prenatal diagnostic assays has traditionally depended on family study analyses. However, this prevents the wide application of prenatal diagnosis based on haplotype analysis, especially in countries with dispersed populations. Here, we present an easy and fast approach using Droplet Digital PCR for the direct determination of haplotype blocks, overcoming the necessity for acquiring other family members’ genetic samples. We demonstrate this approach on nine families that were referred to our center for a prenatal diagnosis of β-thalassaemia using four highly polymorphic single nucleotide variations and the most common pathogenic β-thalassaemia variation in our population. Our approach resulted in the successful direct chromosomal phasing and haplotyping for all nine of the families analyzed, demonstrating a complete agreement with the haplotypes that are ascertained based on family trios. The clinical utility of this approach is envisaged to open the application of prenatal diagnosis for β-thalassaemia to all cases, while simultaneously providing a model for extending the prenatal diagnostic application of other monogenic diseases as well.

Global Globin Network Consensus Paper: Classification and Stratified Roadmaps for Improved Thalassaemia Care and Prevention in 32 Countries

The Global Globin Network (GGN) is a project-wide initiative of the Human Variome/Global Variome Project (HVP) focusing on haemoglobinopathies to build the capacity for genomic diagnosis, clinical services, and research in low- and middle-income countries. At present, there is no framework to evaluate the improvement of care, treatment, and prevention of thalassaemia and other haemoglobinopathies globally, despite thalassaemia being one of the most common monogenic diseases worldwide. Here, we propose a universally applicable system for evaluating and grouping countries based on qualitative indicators according to the quality of care, treatment, and prevention of haemoglobinopathies. We also apply this system to GGN countries as proof of principle. To this end, qualitative indicators were extracted from the IthaMaps database of the ITHANET portal, which allowed four groups of countries (A, B, C, and D) to be defined based on major qualitative indicators, supported by minor qualitative indicators for countries with limited resource settings and by the overall haemoglobinopathy carrier frequency for the target countries of immigration. The proposed rubrics and accumulative scores will help analyse the performance and improvement of care, treatment, and prevention of haemoglobinopathies in the GGN and beyond. Our proposed criteria complement future data collection from GGN countries to help monitor the quality of services for haemoglobinopathies, provide ongoing estimates for services and epidemiology in GGN countries, and note the contribution of the GGN to a local and global reduction of disease burden.

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.

Effect of HBB genotype on survival in a cohort of transfusion-dependent thalassemia patients in Cyprus

Initiation of regular transfusion in transfusion-dependent thalassemia (TDT) is based on the assessment of clinical phenotype. Pathogenic HBB variants causing β-thalassemia are important determinants of phenotype and could be used to aid decision-making. We investigated the association of HBB genotype with survival in a cohort study in the four thalassemia centers in Cyprus. HBB genotype was classified as severe (β0/β0 or β+/β0), moderate (β+/β+), or mild (β0/β++ or β+/β++). Risk factors for mortality were evaluated using multivariate Cox proportional- hazards regression. Of the 537 subjects who were followed for a total of 20,963 person-years, 80.4% (95% confidence interval [95% CI]: 76.4-84.7) survived to 50 years of age with increasing rates of liver-, infectionand malignancy-related deaths observed during recent follow-up. We evaluated non-modifiable risk factors and found worse outcomes associated with male sex (hazard ratio 1.9, 95% CI: 1.1-3.0, P=0.01) and milder genotype (hazard ratio 1.6, 95% CI: 1.1-2.3, P=0.02). The effect of genotype was confirmed in a second model, which included treatment effects. Patients with a milder genotype initiated transfusion significantly later and had reduced blood requirements compared to those with moderate or severe genotypes, although pre-transfusion hemoglobin levels did not differ between genotypes. Our results suggest that early treatment decisions to delay transfusion and different long-term treatment strategies in individuals with milder genotypes have led to adverse longterm effects of under-treated thalassemia and worse survival. We propose that HBB genotype determination and use of this information to aid in decision-making can improve long-term outcomes of thalassemia patients.

A More Universal Approach to Comprehensive Analysis of Thalassemia Alleles (CATSA)

The aim of the study was to assess the clinical utility of a third-generation sequencing (TGS) approach termed comprehensive analysis of thalassemia alleles (CATSA) for identifying both α and β thalassemia genetic carrier status. Prospective blood samples (n = 1759) with abnormal hemoglobin parameters were screened for pathogenic thalassemia variants by CATSA on the PacBio TGS platform. In 1159 individuals, a total of 1317 pathogenic thalassemia variants were identified and confirmed by independent PCR-based tests. Of the total thalassemia variants detected, the α-variant --^SEA (35.4%) and β-variant c.126_129delCTTT (15%) were the most common. CATSA was also able to detect three types of rare HBA structural variants as well as five rare HBA2, three HBA1, and 10 HBB single-nucleotide variations/insertions and deletions. Compared with standard thalassemia variant PCR panel testing, CATSA identified all panel variants present, with no false-negative results. Carrier assignment was improved through identification of rare variants missed by the panel test. On the basis of allelic coverage, reliability, and accuracy, TGS with long-range PCR presents a comprehensive approach with the potential to provide a universal solution for thalassemia genetic carrier screening. It is proposed that CATSA has immediate clinical utility as an effective carrier screening approach for at-risk couples.

The Spectrum of β-Thalassemia Mutations in the Population Migration in Lebanon: A 6-Year Retrospective Study

β-Thalassemia (β-thal) is highly prevalent among the Mediterranean populations. In Lebanon, the carrier rate of the disease is estimated to be around 2.0-3.0%. In this retrospective study, we determined the spectrum of β-thal mutations in a total of 170 individuals from a sample of 140 Lebanese, Iraqi and Syrian refugee families in Lebanon, over a period from 2012 to 2018. Twenty-eight different β-globin gene mutations were identified. The most prevalent mutations were IVS-I-110 (G>A) (HBB: c.93-21G>A), IVS-II-1 (G>A) (HBB: c.315+1G>A), IVS-I-6 (T>C) (HBB: c.92+6T>C) and IVS-I-1 (G>A) (HBB: c.92+1G>A), accounting for the majority of mutations found in HBB mutations analysed in 250 alleles. Ten different β-globin gene mutations that were not previously described in Lebanon were identified in our study. These mutations include the IVS-II-848 (C>A) (HBB: c.316-3C>A), codons 9/10 (+T) (HBB: c.30_31insT), codon 15 (-T) (HBB: c.46delT), -86 (C>G) (HBB: c.-136C>G), Cap +22 (G>A) (HBB: c.-29G>A), -28 (A>C) (HBB: c.-78A>C), codon 7 (GAG>TAG) (HBB: c.22G>T), codon 26 (GAG>TAG) (HBB: c.79G>T), codons 41/42 (-TTCT) (HBB: c.126_129delCTTT), and codons 82/83 (-G) (HBB: c.250delG). Of these, six mutations [codons 9/10, codon 15 (-T), -86, codon 7, codon 26, codons 82/83) were identified in Lebanese samples only; one mutation (IVS-II-848) was identified in both Lebanese and Iraqis; and three mutations (Cap +22, -28, codons 41/42) were identified in Iraqi samples only. Further studies will help better delineate the spectrum of β-thal mutations among different ethnic groups, and provide crucial prevention strategies.

The Story of a Ship Journey, Malaria, and the HBB Gene IVS-II-745 Mutation: Circassian Immigration to Cyprus

Background  During 19th century, the Circassians were secluded from their lands and forced to migrate to Ottoman Empire properties. Approximately 2,346 Circassians were exiled from Istanbul to Cyprus Island. During the deportation journey, many of Circassian passed away in consequence of malaria and unknown reasons. Overall, 1,351 survivor Circassians managed to reach the island, however, many of them had faced with endemic malaria again in Cyprus. An autosomal recessive hematological disorder thalassemia was the second endemic health condition after malaria, whereas thalassemia carriers show resistance to malaria infections.

Materials and Methods  A large Cypriot family with 57 members whose grandparents were supposed to be in that ship journey has been investigated in this study. Polymerase chain reaction (PCR)–amplification refractory mutation system (ARMS) analysis technique was used for genotyping the HHB gene.

Results  The human β-globin ( HBB ) gene c.316–106C > G (IVS-II-745) (II-745) heterozygous variation have been detected.

Conclusion  Overall, this study is a very good example for a typical natural selection. In this case, one single gene point mutation did not limit survival in the society; natively, it increased their survival changes to form new colonization and the inheritance of the mutation to the next generations.

A Southeast Asian Perspective on the COVID-19 Pandemic: Hemoglobin E (HbE)-Trait Confers Resistance Against COVID-19

As of November 25, 2020, over 60 million people have been infected worldwide by COVID-19, causing almost 1.43 million deaths. Puzzling low incidence numbers and milder, non-fatal disease have been observed in Thailand and its Southeast (SE) Asian neighbors. Elusive genetic mechanisms might be operative, as a multitude of genetic factors are widely shared between the SE Asian populations, such as the more than 60 different thalassemia syndromes (principally dominated by the HbE trait). In this study, we have plotted COVID-19 infection and death rates in SE Asian (SEA) countries against heterozygote HbE and thalassemia carrier prevalence. COVID-19 infection and death incidence numbers appear inversely correlated with the prevalence of HbE and thalassemia heterozygote populations. We posit that the evolutionary protective effect of the HbE and other thalassemic variants against malaria and the dengue virus may extend its advantage to resistance to COVID-19 infection, as HbE heterozygote population prevalence appears to be positively correlated with immunity to COVID-19. Host immune system modulations induce antiviral interferon responses and alter structural protein integrity, thereby inhibiting cellular access and viral replication. These changes are possibly engendered by HbE carrier miRNAs. Proving this hypothesis is important, as it may shed light on the mechanism of viral resistance and lead to novel antiviral treatments. This development can thus guide decision-making and action to prevent COVID-19 infection.

The spectrum of beta-thalassemia mutations in the 22 Arab countries: a systematic review

OBJECTIVES

To investigate the mutational spectrum in the HBB gene in Arab patients with β-thal.

METHODS

Authors searched five databases (PubMed, Science Direct, Scopus, Web of Science, and Google Scholar) from the time of inception until March 2020.

RESULTS

The authors search strategy yielded 3,229 citations, of which 48 eligible studies captured. 105 mutations were captured, of these, 99 were shared between Arabs and other ethnic groups, six mutations were unique to Arabs (c.92 + 2 T > G, c.-240 G > A, c.150delC, c.420dupT, deletion of 192 bp spanning exon 1, intron 1, and the first two bases of exon 2 of HBB gene, and deletion of 9.6 kb, including exon 1 and intron 2 of HBB gene). The most common HBB gene mutations among Arabs were c.93-21 G > A, c.118 C > T, c.92 + 1 G > A, c.92 + 6 T > C, c.92 + 5 G > C, c.315 + 1 G > A, and c.27dupG. Consanguinity is high among Arab patients with β-thal. Migration into Arab countries led to allelic heterogeneity among Arab patients with β-thal.

CONCLUSION

Our findings present a platform for further genetic epidemiological studies for Arab patients with β-thal.

Changing patterns in the epidemiology of β-thalassemia

β‐thalassemia major is an inherited hemoglobinopathy that requires lifelong red blood cell transfusions and iron chelation therapy to prevent complications due to iron overload. Traditionally, β‐thalassemia has been more common in certain regions of the world such as the Mediterranean, Middle East, and Southeast Asia. However, the prevalence of β‐thalassemia is increasing in other regions, including Northern Europe and North America, primarily due to migration. This review summarizes the available data on the changing incidence and prevalence of β‐thalassemia as well as factors influencing disease frequency. The data suggest that the epidemiology of β‐thalassemia is changing: Migration has increased the prevalence of the disease in regions traditionally believed to have a low prevalence, while, at the same time, prevention and screening programs in endemic regions have reduced the number of affected individuals. Various approaches to prevention and screening have been used. Region‐specific prevention and treatment programs, customized to align with local healthcare resources and cultural values, have been effective in identifying patients and carriers and providing information and care. Significant challenges remain in universally implementing these programs.

Novel genetic therapeutic approaches for modulating the severity of β-thalassemia (Review)

Thalassemia is a genetic haematological disorder that arises due to defects in the α and β-globin genes. Worldwide, 0.3-0.4 million children are born with haemoglobinopathies per year. Thalassemic patients, as well as their families, face various serious clinical, socio-economic, and psychosocial challenges throughout their life. Different therapies are available in clinical practice to minimize the suffering of thalassemic patients to some extent and potentially cure the disease. Predominantly, patients undergo transfusion therapy to maintain their haemoglobin levels. Due to multiple transfusions, the iron levels in their bodies are elevated. Iron overload results in damage to body organs, resulting in heart failure, liver function failure or endocrine failure, all of which are commonly observed. Certain drugs have been developed to enhance the expression of the γ-gene, which ultimately results in augmentation of fetal haemoglobin (HbF) levels and total haemoglobin levels in the body. However, its effectiveness is dependent on the genetic makeup of the individual patient. At present, allogeneic haematopoietic Stem Cell Transplantation (HSCT) is the only practically available option with a high curative rate. However, the outcome of HSCT is strongly influenced by factors such as age at transplantation, irregular iron chelation history before transplantation, histocompatibility, and source of stem cells. Gene therapy using the lentiglobin vector is the most recent method for cure without any mortality, graft rejection and clonal dominance issues. However, delayed platelet engraftment is being reported in some patients. Genome editing is a novel approach which may be used to treat patients with thalassemia; it makes use of targeted nucleases to correct the mutations in specific DNA sequences and modify the sequence to the normal wild-type sequence. To edit the genome at the required sites, CRISPR/Cas9 is an efficient and accurate tool that is used in various genetic engineering programs. Genome editing mediated by CRISPR/Cas9 has the ability to restore the normal β-globin function with minimal side effects. Using CRISPR/Cas9, expression of BCL11A can be downregulated along with increased production of HbF. However, these genome editing tools are still under in-vitro trials. CRISPR/Cas9 has can be used for precise transcriptional regulation, genome modification and epigenetic editing. Additional research is required in this regard, as CRISPR/Cas9 may potentially exhibit off-target activity and there are legal and ethical considerations regarding its use.

A decision support scheme for beta thalassemia and HbE carrier screening

The most effective way to combat β-thalassemias is to prevent the birth of children with thalassemia major. Therefore, a cost-effective screening method is essential to identify β-thalassemia traits (BTT) and differentiate normal individuals from carriers. We considered five hematological parameters to formulate two separate scoring mechanisms, one for BTT detection, and another for joint determination of hemoglobin E (HbE) trait and BTT by employing decision trees, Naïve Bayes classifier, and Artificial neural network frameworks on data collected from the Postgraduate Institute of Medical Education and Research, Chandigarh, India. We validated both the scores on two different data sets and found 100% sensitivity of both the scores with their respective threshold values. The results revealed the specificity of the screening scores to be 79.25% and 91.74% for BTT and 58.62% and 78.03% for the joint score of HbE and BTT, respectively. A lower Youden's index was measured for the two scores compared to some existing indices. Therefore, the proposed scores can obviate a large portion of the population from expensive high-performance liquid chromatography (HPLC) analysis during the screening of BTT, and joint determination of BTT and HbE, respectively, thereby saving significant resources and cost currently being utilized for screening purpose.

Beta-Thalassemia Intermedia: A Single Thalassemia Center Experience from Northeastern Iraq

OBJECTIVE

To determine the molecular characterization and disease-associated complications of beta-thalassemia intermedia (β-TI) patients in Sulaymaniyah province, northeastern Iraq.

METHODS

A total of 159 β-TI) patients in Sulaymaniyah province, northeastern Iraq. β-TI) patients in Sulaymaniyah province, northeastern Iraq.

RESULTS

Nineteen different β-globin gene mutations arranged in 37 various genotypes were determined. The most frequent were IVS-II-I (G>A) (47.2%), followed by IVS-I-6 (T>C) (23.3%) and IVS-I-110 (G>A) (5%). Among disease-related morbidities documented, bone disease amounted to 53% (facial deformity and osteoporosis), followed by endocrinopathies 17.6% (growth retardation and subclinical hypothyroidism), cholelithiasis 13.8%, pulmonary hypertension 11.3%, and abnormal liver function test 7.5%, whereas venous thrombosis, extramedullary hemopoiesis, and leg ulcer were less frequently observed. Age ≥ 35 and female sex were risk factors for cholelithiasis, while age was an independent risk for hypothyroidism and female sex was associated with increased risk for osteoporosis. Mean serum ferritin of ≥1000 μg/L was associated with an increased risk of osteoporosis, whereas chelation therapy was protective for a multitude of other complications. Transfusion, on the other hand, increased the risk of osteoporosis, yet it was protective for cholelithiasis and hypothyroidism. Moreover, splenectomy was protective for cholelithiasis, although it was an independent risk for hypothyroidism. Finally, hydroxyurea was associated with an increased risk of osteoporosis, while it was protective for cholelithiasis. Discussion and Conclusion. β +-thalassemia mutation had contributed to 41.25 of families with a less severe β-thalassemia phenotype in the northeastern part of Iraq, justifying the need to investigate the contribution of genetic modifiers in ameliorating disease severity. In addition, the substantial number of β-TI patients developed disease-related morbidities, which necessitates the need for more appropriate clinical management with earlier intervention.β-TI) patients in Sulaymaniyah province, northeastern Iraq. μg/L was associated with an increased risk of osteoporosis, whereas chelation therapy was protective for a multitude of other complications. Transfusion, on the other hand, increased the risk of osteoporosis, yet it was protective for cholelithiasis and hypothyroidism. Moreover, splenectomy was protective for cholelithiasis, although it was an independent risk for hypothyroidism. Finally, hydroxyurea was associated with an increased risk of osteoporosis, while it was protective for cholelithiasis. Discussion and Conclusion. β +-thalassemia mutation had contributed to 41.25 of families with a less severe β-thalassemia phenotype in the northeastern part of Iraq, justifying the need to investigate the contribution of genetic modifiers in ameliorating disease severity. In addition, the substantial number of β-TI patients developed disease-related morbidities, which necessitates the need for more appropriate clinical management with earlier intervention.Discussion and Conclusion. β +-thalassemia mutation had contributed to 41.25 of families with a less severe β-thalassemia phenotype in the northeastern part of Iraq, justifying the need to investigate the contribution of genetic modifiers in ameliorating disease severity. In addition, the substantial number of β-TI patients developed disease-related morbidities, which necessitates the need for more appropriate clinical management with earlier intervention.β-TI) patients in Sulaymaniyah province, northeastern Iraq. β-TI) patients in Sulaymaniyah province, northeastern Iraq.

A novel mutation in the erythroid transcription factor KLF1 is likely responsible for ameliorating β-thalassemia major

We describe the identification of a novel missense mutation in the second zinc finger of KLF1 in two siblings who, based on their genotype, are predicted to suffer from beta thalassemia major but are, in fact, transfusion‐free and in good health. These individuals, as well as two additional members of the same family also carrying this KLF1 mutation, exhibit high levels of fetal hemoglobin (HbF). KLF1 is an erythroid transcription factor, which plays a critical role in the regulation of the developmental switch between fetal and adult hemoglobin by regulating the expression of a multitude of genes including that of BCL11A. The mutation appears to be the main candidate responsible for the beta thalassemia‐ameliorating effect as this segregates with the observed phenotype and also exogenous expression of the KLF1 mutant protein in human erythroid progenitor cells resulted in the induction of γ‐globin, without, however, affecting BCL11A levels. This report adds to the weight of evidence that heterozygous KLF1 mutations can ameliorate the severity of the β‐thalassemia major phenotype.

Molecular epidemiology, pathogenicity, and structural analysis of haemoglobin variants in the Yunnan province population of Southwestern China

Abnormal haemoglobin (Hb) variants result in the most commonly inherited disorders in humans worldwide. In this study, we investigated the molecular epidemiology characteristics of Hb variants, along with associated structural and functional predictions in the Yunnan province population of Southwestern China. A total of 41,933 subjects who sought haemoglobinopathy screening were included. Based on bioinformatics and structural analysis, as well as protein modeling, the pathogenesis and type of Hb genetic mutations were characterized. Among all individuals studied, 328 cases (0.78%) were confirmed as carriers of Hb variants, with 13 cases (0.03%) presenting α-globin variants, 313 (0.75%) β-globin variants, and two δ-globin variants. A total of 19 different mutations were identified, including three novel mutations. In addition, 48 cases of αα^CS mutations and 14 cases of Hb H or Hb Bart’s were found. The isoelectric point, evolutionary conservation, and genotype-phenotype correlation for these mutations were predicted. Additionally, secondary and tertiary protein structure modeling were performed for three selected mutations. In conclusion, the prevalence of Hb variants in the Yunnan population is much higher than other regions of China. Complete characterization of these Hb variants is essential for generating a rational strategy to control the haemoglobinopathies in this region.

The phenotypic and molecular diversity of hemoglobinopathies in India: A review of 15 years at a referral center

INTRODUCTION

The hemoglobinopathies pose a significant health burden in India. Apart from the β thalassemias and sickle cell disorders, α thalassemias and structural hemoglobin variants are also common. Here we have reviewed the phenotypic and molecular diversity of hemoglobinopathies encountered at a referral center in western India over a period of 15 years.

MATERIALS AND METHODS

Screening for hemoglobinopathies was done using HPLC and cellulose acetate electrophoresis. Molecular characterization was done using Covalent Reverse Dot Blot Hybridization (CRDB), Amplification Refractory Mutation System (ARMS), GAP PCR and direct DNA sequencing.

RESULTS

The study includes 31 075 individuals who were referred for diagnosis of hemoglobinopathies and prenatal diagnosis. Of these 14 423 individuals showed various hemoglobin abnormalities. Beta genotyping in 5615 individuals showed the presence of 49 β thalassemia mutations. 143 β thalassemia heterozygotes had normal or borderline HbA₂ levels. We identified three δ gene mutations (HbA₂ Pellendri, HbA₂ St.George, HbA₂ Saurashtra) in β thalassemia heterozygotes leading to normal HbA₂ levels. The commonest defects among the raised Hb F determinants were Gγ(Αγδβ)⁰ Indian inversion and the HPFH-3 Indian deletion. A total of 312 individuals showed the presence of α thalassemia, of which 12.0% had a single α gene deletion (-α/αα). HbH disease was identified in 29 cases with 10 different genotypes. Alpha globin gene triplication was seen in 2.1% of β thalassemia heterozygotes with a thalassemia intermedia phenotype. Seven unusual α chain variants and eight uncommon β chain variants were identified.

CONCLUSION

The repertoire of molecular defects seen in the different globin genes will be valuable for management and control of these disorders both in India as well as in other countries where there is a huge influx of migrant populations from India.

Fast Temperature-Gradient COLD PCR for the enrichment of the paternally inherited SNPs in cell free fetal DNA; an application to non-invasive prenatal diagnosis of β-thalassaemia

Objective

To develop a sensitive, specific, simple, cost-effective and reproducible platform for the non-invasive prenatal detection of paternally inherited alleles for β-thalassaemia. The development of such an assay is of major significance in order to replace currently-applied invasive methods containing inherent fetal loss risks.

Methods

We present a fast Temperature-Gradient Co-amplification at Lower Denaturation Temperature Polymerase Chain Reaction (fast TG COLD PCR) methodology for the detection of the paternally-inherited fetal alleles in maternal plasma. Two single-nucleotide polymorphisms (SNPs), rs7480526 (G/T) and rs968857 (G/A) that are located on the β-globin gene cluster and exhibit a high degree of heterozygosity in the Cypriot population were selected for evaluation. Seventeen maternal plasma samples from pregnancies at risk for β-thalassemia were analysed for the selected SNPs using the novel fast TG COLD PCR assay.

Results

Using fast TG COLD PCR, the paternally inherited allele in cell free fetal DNA was correctly determined for all the 17 maternal plasma samples tested, showing full agreement with the Chorionic Villus Sampling (CVS) analysis.

Conclusions

Our findings are encouraging and demonstrate the efficiency and sensitivity of fast TG COLD PCR in detecting the minor paternally-inherited fetal alleles in maternal plasma for the development of a NIPD assay for β-thalassaemia.

First Cases of Hb Agrinio Described in Patients from the Republic of Macedonia

Previous molecular analyses of α-thalassemia (α-thal) in the Republic of Macedonia have identified the following genetic defects: -α^3.7 (rightward), -(α)^20.5 and - -^MED I deletions and Hb Icaria [α142, Term→Lys (α2), HBA2: c.427T>A] and polyadenylation signal (polyA) [AATAAA>AATGAA (α2), HBA2: c.*92A>G] point mutations. Here, we report two unrelated patients from the Romani population in the Republic of Macedonia, homozygotes for the α2-globin gene variant Hb Agrinio [α29(B10)Leu→Pro; HBA2: c.89T>C]. To date, Hb Agrinio has been described only in individuals of Greek, Cypriot and Spanish origin. Both of our patients had early presentation of the disease (3.5 years and 2 months, respectively) with frequent blood transfusions from early infancy. They have a severe intermediate phenotype of thalassemia (Hb H disease) with hemoglobin (Hb) levels of 7.8 and 7.7 g/dL, respectively. Although the HBA2: c.89T>C mutation results in an α⁺ allele, the severe phenotype of the homozygotes is due to the production of hyperunstable α chains that undergo post translational precipitation. This leads to a greater degree of red cell damage and hemolytic anemia. The detection of Hb Agrinio in two unrelated families of Romani ethnic origin, may suggest it is a founder mutation in this population living in the Republic of Macedonia. Considering the severity of the clinical presentation of the homozygotes or compound heterozygotes for this rare Hb variant, a targeted molecular screening for Hb Agrinio mutation carriers should be considered in all patients of Romani ethnic origin with manifested microcytosis.

β-Thalassemia Distribution in the Old World: an Ancient Disease Seen from a Historical Standpoint

Background

Haemoglobinopathies constitute the commonest recessive monogenic disorders worldwide, and the treatment of affected individuals presents a substantial global disease burden. β-thalassaemia is characterised by the reduced synthesis (β⁺) or absence (β^o) of the β-globin chains in the HbA molecule, resulting in accumulation of excess unbound α-globin chains that precipitate in erythroid precursors in the bone marrow and in the mature erythrocytes, leading to ineffective erythropoiesis and peripheral haemolysis. Approximately 1.5% of the global population are heterozygotes (carriers) of the β-thalassemias; there is a high incidence in populations from the Mediterranean basin, throughout the Middle East, the Indian subcontinent, Southeast Asia, and Melanesia to the Pacific Islands.

Aim

The principal aim of this paper is to review, from a historical standpoint, our knowledge about an ancient disease, the β-thalassemias, and in particular, when, how and in what way β-thalassemia spread worldwide to reach such high incidences in certain populations.

Results

Mutations involving the β-globin gene are the most common cause of genetic disorders in humans. To date, more than 350 β-thalassaemia mutations have been reported. Considering the current distribution of β- thalassemia, the wide diversity of mutations and the small number of specific mutations in individual populations, it seems unlikely that β-thalassemia originated in a single place and time.

Conclusions

Various processes are known to determine the frequency of genetic disease in human populations. However, it is almost impossible to decide to what extent each process is responsible for the presence of a particular genetic disease. The wide spectrum of β-thalassemia mutations could well be explained by looking at their geographical distribution, the history of malaria, wars, invasions, mass migrations, consanguinity, and settlements. An analysis of the distribution of the molecular spectrum of haemoglobinopathies allows for the development and improvement of diagnostic tests and management of these disorders.

Hb A2 Episkopi - a novel δ-globin chain variant [HBD:c.428C>T] in a family of mixed Cypriot-Lebanese descent

OBJECTIVES

Thalassaemia is a potentially lethal inherited anaemia, caused by reduced or absent synthesis of globin chains. Measurement of the minor adult haemoglobin Hb A₂, combining α- with δ-globin, is critical for the routine diagnosis of carrier status for α- or β-thalassaemia. Here, we aim to characterize a novel δ-globin variant, Hb A₂ Episkopi, in a single family of mixed Lebanese and Cypriot ancestry with mild hypochromic anaemia and otherwise normal globin genotype, which also presents with a coincidental 0.78-Mb sequence duplication on chromosome 1 (1q44) and developmental abnormalities.

METHODS

Analyses included comprehensive haematological analyses, cation-exchange high-performance liquid chromatography (CE-HPLC), cellulose acetate electrophoresis (CAE), Sanger sequencing and structure-based stability predictions for Hb A₂ Episkopi.

RESULTS

The GCT > GTT missense mutation, underlying Hb A₂ Episkopi, HBD:c.428C > T, introduces a cd142 codon change in the mature protein, resulting in reduced normal Hb A₂ amounts and a novel, less abundant Hb A₂ variant (HGVS: HBD:p.A143V), detectable as a delayed peak by CE-HPLC. The latter was in line with structure-based stability predictions, which indicated that the substitution of a marginal, non-helical and non-interface residue, five amino acids from the δ-globin chain carboxy-terminus, was moderately destabilizing.

DISCUSSION

Detection of the new variant depends on the diagnostic set-up and had failed by CAE and on an independent CE-HPLC system, which, in unfavourable circumstances, may lead to misdiagnoses of β-thalassaemia as α-thalassaemia. Given the mixed background of the affected family, the ethnic origin of the mutation is unclear, and this study thus suggests awareness for possible detection of Hb A₂ Episkopi in both the Cypriot and the Lebanese populations.