Analysis of the Haematological Phenotype and Molecular Characteristics of Rare Abnormal Haemoglobin.

BACKGROUND: Haemoglobinopathy refers to a group of common monogenic inherited conditions associated with variations in the haemoglobin molecule; however, there is relatively limited reporting on abnormal haemoglobinopathy in the Chinese population, especially rare abnormal haemoglobin (Hb). The aim of this study was to explore the clinical characteristics of haemoglobinopathy to supplement data for the epidemiological investigation of Hb variants in Guangdong province of China. METHODS: Peripheral blood was collected from five patients (including a family) for Complete blood count, Hb electrophoresis, High-performance liquid chromatography analysis and degenerative globin body testing. Hb variants were further analysed by PCR and DNA sequencing. RESULTS: The research subjects were diagnosed with different types of abnormal Hb. The blood routine of the Hb Fukuyama (HBB:c.232C>T) diagnosed individual showed microcytic hypochromic anaemia, with a lower Hb level (64 g/L), mean corpuscular volume (MCV) of 71.5 fL and mean corpuscular haemoglobin (MCH) of 21.5 pg. Individuals diagnosed with Hb Port Phillip (HBA2:c.275T>C) exhibit a MCH level that is slightly below average, at 26.4 pg. The Hb Saint Etienne (HBB:c.279C>G) diagnosed individual showed macrocytic hypochromic anaemia, and the proband had a low Hb level (116 g/L), MCV of 102.2 fL and MCH of 29.4 pg. CONCLUSION: We confirmed the presence of Hb Fukuyama (HBB:c.232C>T) in China for the first time. Three rare patients with the Hb Saint Etienne (HBB:c.279C>G) phenotype and one patient with Hb Port Phillip (HBA2:c.275T>C) phenotype were included. Our research enriches the gene mutation map of haemoglobinopathy in Guangdong province and improves the detection system of haemoglobinopathy for population prevention and eugenics.

Hemoglobin J-Auckland: a clinically silent low oxygen affinity variant presenting with persistent asymptomatic hypoxemia at high altitude.

BACKGROUND: Inherited hemoglobin disorders are common in clinical practice. While qualitative (i.e. sickle cell disease) and quantitative (thalassemia) hemoglobinopathies are usually diagnosed clinically and confirmed through simple laboratory assessments, hemoglobin variants with altered oxygen affinity often go undetected due to their typically silent clinical presentation. Hemoglobin (Hb) J-Auckland, a low oxygen affinity hemoglobin variant first described in 1987 in Auckland, New Zealand, is one such silent disorder. CASE PRESENTATION: We report for the first time a clinically evident case of previously undiagnosed Hb J-Auckland in an 8-year-old girl who presented with unexplained hypoxemia at high altitude. Her oxygen level was corrected with supplemental oxygen and when assessed at low altitude. A brief discussion of the diagnostic approach and clinical implications is provided. CONCLUSION: Standard hemoglobin analysis is essential for the evaluation of suspected altered affinity hemoglobinopathy, and genetic testing is often required for definitive diagnosis. Early recognition and diagnosis of these variants can prevent mismanagement and improve patient outcomes.

Interactions of electrophoretically silent hemoglobin Hekinan II [HBA1:c.84G>T] with various forms of α-thalassemias and other hemoglobinopathies: novel insights into the molecular and hematological characteristics and genetic origins.

To determine the molecular basis, genotype - phenotype relationship, and genetic origin of Hemoglobin (Hb) Hekinan associated with several forms of α-thalassemia and other hemoglobinopathies for a better understanding of its diverse clinical phenotypes. Seventeen participants with suspected abnormal Hb were studied. Hb analysis was performed using high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). Mutational and α-haplotypic and structural analyses were conducted, and the effects of mutations on globin-chain stability were determined. All participants harbored Hb Hekinan II (HBA1:c.84 G>T) co-inherited with another α-globin gene anomaly. Three novel genotypes, (ααHekinan/αCSα), (ααHekinan/αCSα,ßA/ßE), and (ααHekinan/αCSα,ßE/ßE), were characterized. Despite being co-inherited with both α- and ß-Hb variants Hb Hekinan II led to minimal changes in erythrocyte parameters, suggesting a non-pathological nature. HPLC but not CE revealed a distinct small shoulder-like Hb pattern. Thai Hb Hekinan II was strongly associated with haplotype [+ - S + - - -] and the possibility of four different haplotypes, while two Burmese Hb Hekinan II were associated with haplotypes [± - S + - + -] and [± - S + - - -]. The novel genotypes identified provide a fresh perspective on Hb Hekinan II diversity. HPLC has superior identification capabilities for samples of Hb Hekinan II co-inherited with α-thalassemia. Thai and Burmese Hb Hekinan II have diverse origins.

A Review of Gene Therapies for Hemoglobinopathies.

Due to the significant morbidity and mortality of hemoglobinopathies, curative options have long been pursued. The overall goal of gene therapy is to modify a patient's own hematopoietic stem cells to overcome the deleterious effects of the underlying genetic defect by gene addition, gene editing, or gene silencing. Gene addition incorporates genes with superior function than the abnormal gene; gene editing takes advantage of molecular tools such as zinc finger proteins, Transcription Activator-Like Effector Nucleases and Clustered Regularly Interspaced Short Palindromic Repeats coupled with Cas9 proteins (CRISPR-Cas9) which allow for sequence-specific breaks in DNA that disrupt gene function; and gene silencing suppresses gene expression by interference with mRNA transcription/protein translation or epigenetic modification. The majority of gene therapy strategies for hemoglobinopathies have targeted erythroid-specific BCL11A, a major regulator of fetal hemoglobin repression at the gamma-globin locus, in the normal fetal-to-adult hemoglobin switch that occurs shortly after birth. Other goals have involved the incorporation of anti-sickling globins, such as ßT87Q or ßAS3. Landmark clinical trials of gene therapy in transfusion-dependent thalassemia and sickle cell disease have shown remarkable efficacy and acceptable safety and culminated in recent regulatory approvals of gene therapy for both diseases in Europe and the United States.

Family study of haemoglobin Arya in a Malaysian family.

INTRODUCTION: Thalassemia and haemoglobinopathies are relatively common among Malaysians. One of the rare haemoglobinopathies reported is Haemoglobin (Hb) Arya, which occurs due to substitution of aspartic acid at residue 47 of the alpha chain by asparagine. Here, we report the detection of Hb Arya in a Malaysian family, which was detected incidentally during family screening. CASE REPORT: A 16 years-old girl, clinically asymptomatic was noted to have low mean corpuscular haemoglobin (MCV) with normal Hb level. Hb analysis using capillary electrophoresis (CE) showed reduced Hb A of 76.5%, Hb A2 of 1.6% with presence of small peak at Zone 1 likely A2'. There was also a small peak noted at Hb D zone and Hb S zones which quantified as 1.5% and 20% respectively. Supplementary test by high performance liquid chromatography (HPLC) showed a prominent peak at D-window (19.6%) and a small peak at S-window (0.6%). DNA analysis revealed a heterozygous state of α2 codon 47 Hb Arya mutation. Subsequent family study showed a similar mutation in the father and sister of the index case. CONCLUSION: Very few reports are available up to date regarding Hb Arya. This report highlights the rare haemoglobinopathy in a Malay family in Malaysia that contributes to the growing literature of this rare haemoglobin variant.

Hemoglobin Oviedo (c.115A > G; p.T39A): A Cause of Low Oxygen Saturation.

We report a new low-affinity hemoglobinopathy (Hemoglobin Oviedo) in a family with isolated low oxygen saturation (89-92%) caused by a previously undescribed variant (NM_000518.5: c.115A > G;p.Thr39Ala) in the hemoglobin subunit ß encoding gene (HBB gene) located on chromosome 11.

Advances in Hemoglobinopathies and Thalassemia Evaluation.

Hemoglobin (Hb) disorders are among the most prevalent inherited diseases. Despite a limited number of involved genes, these conditions represent a broad clinical and prognostic spectrum. The menu of laboratory tests is extensive. From widely available modalities, for example, complete blood count to rather sophisticated molecular technologies, the investigation of Hb disorders recapitulates an increasing complexity of laboratory workup in other medical fields. This review highlights a current state of biochemical and molecular investigation of Hb disorders and offers a glimpse on technologies that are yet to be fully embraced in clinical practice.

Prevalence and Regional Distribution of Beta-Hemoglobin Variants in Saudi Arabia: Insights from the National Premarital Screening Program".

BACKGROUND: Hemoglobinopathies are among the most prevalent inherited disorders globally, with carrier prevalence varying significantly across regions. In Saudi Arabia, high rates of consanguineous marriages amplify the risk of these disorders. AIM: This study aims to assess the burden of hemoglobinopathies by evaluating the prevalence and regional distribution of beta-hemoglobin variants, including rare variants, among couples participating in the national premarital screening program. METHODS: Data were collected from the premarital genetic screening program and entered into the SEHA platform, covering the 13 administrative regions of Saudi Arabia. Blood samples underwent various screening tests for infectious and genetic diseases. Hemoglobin electrophoresis samples were analyzed using capillary electrophoresis, High-Performance Liquid Chromatography (HPLC), or a combination of both methods. RESULTS: From 2011 to 2018, 1,871,184 individuals were included in the study, with 49.8% male and 50.2% female. The average age was 30.2 years. Hemoglobin S (HbS) was identified in 88,431 individuals (4.7% of the tested population and 78.5% of abnormal screening results), primarily as a sickle cell trait. ß-thalassemia was the second most common disorder, identified in 22,420 individuals (1.2% of the population and 19.9% of hemoglobin disorders). HbC and HbD were each detected in 0.04% of cases, while HbO-Arab was identified in 0.007% and HbG in 0.006%. Hemoglobin E and hemoglobin Lepore were found to be extremely rare. CONCLUSION: The study demonstrates regional variation in the prevalence of hemoglobin genetic variants in Saudi Arabia. To effectively mitigate this risk, it is imperative to strengthen public education and awareness, particularly focusing on genetic screening and counseling.

Preclinical safety assessment of modified gamma globin lentiviral vector-mediated autologous hematopoietic stem cell gene therapy for hemoglobinopathies.

Previously, we reported the development of a human Aγ-globin gene lentivirus (LV), GbG, which expresses high levels of HbF to correct the sickle cell anemia (SCA) phenotype in the Berkeley SCA mouse model, and then modified the γ-globin gene by substituting glycine at codon 16 with aspartic acid in the Aγ-globin gene to generate GbGM LV. In the present study, we evaluated the long-term safety of human Aγ-globin gene carrying GbGM LV in wild-type mice after primary and secondary transplants of GbGM-modified hematopoietic stem cells (HSC) over 18 months. The safety of the GbGM bone marrow transplant was assessed by monitoring the effects on body weight, hematology, histopathology, malignancy formation, and survival. Mice transplanted with Mock-transduced and spleen focus forming virus (SFFV) γ-retroviral vector (RV)-transduced HSC served as negative and positive controls, respectively. The mean donor-cell engraftment was comparable across Mock, GbGM LV, and SFFV RV groups. There were no significant differences in body weight, clinical signs, immunophenotype, or histopathology in the GbGM-treated mice compared to controls. Four SFFV RV-treated mice, but none of the GbGM-treated mice, developed donor-derived, vector-positive lymphomas as demonstrated by flow cytometry analysis and in situ hybridization. These results highlight the safety of the administration of GbGM LV-modified HSC with long-term follow-up after primary and secondary transplants in mice. This data supported the initiation of phase 1/2 first-in-human SCA clinical trial in the United States.

Non-invasive prenatal testing of beta-hemoglobinopathies using next generation sequencing, in-silico sequence size selection, and haplotyping.

AIM: To develop a non-invasive prenatal test for beta-hemoglobinopathies based on analyzing maternal plasma by using next generation sequencing. METHODS: We applied next generation sequencing (NGS) of maternal plasma to the non-invasive prenatal testing (NIPT) of autosomal recessive diseases, sickle cell disease and beta-thalassemia. Using the Illumina MiSeq, we sequenced plasma libraries obtained via a Twist Bioscience probe capture panel covering 4 Kb of chromosome 11, including the beta-globin (HBB) gene and >450 genomic single-nucleotide polymorphisms (SNPs) used to estimate the fetal fraction (FF). The FF is estimated by counting paternally transmitted allelic sequence reads present in the plasma but absent in the mother. We inferred fetal beta-globin genotypes by comparing the observed mutation (Mut) and reference (Ref) read ratios to those expected for the three possible fetal genotypes (Mut/Mut; Mut/Ref; Ref/Ref), based on the FF. RESULTS: We bioinformatically enriched the FF by excluding reads over a specified length via in-silico size selection (ISS), favoring the shorter fetal reads, which increased fetal genotype prediction accuracy. Finally, we determined the parental HBB haplotypes, which allowed us to use the read ratios observed at linked SNPs to help predict the fetal genotype at the mutation site(s). We determined HBB haplotypes via Oxford Nanopore MinION sequencing of a 2.2 kb amplicon and aligned these sequences using Soft Genetics' NextGENe LR software. CONCLUSION: The combined use of ISS and HBB haplotypes enabled us to correctly predict fetal genotypes in cases where the prediction based on variant read ratios alone was incorrect.

The Application of Clinical and Molecular Diagnostic Techniques to Identify a Rare Haemoglobin Variant.

Haemoglobin disorders represent a heterogeneous group of inherited conditions that involve at least one genetic abnormality in one or more of the globin chains, resulting in changes in the structure, function, and/or amount of haemoglobin molecules, which are very important for their related clinical aspects. Detecting and characterizing these disorders depends primarily on laboratory methods that employ traditional approaches and, when necessary, newer methodologies essential for solving a number of diagnostic challenges. This review provides an overview of key laboratory techniques in the diagnosis of haemoglobinopathies, focusing on the challenges, advancements, and future directions in this field. Moreover, many haemoglobinopathies are benign and clinically silent, but it is not uncommon to find unexpected variants during routine laboratory tests. The present work reported a rare and clinically interesting case of identification of haemoglobin fractions in an adult man by the determination of glycated haemoglobin (HbA1c) during a routine laboratory assessment, highlighting how the correct use of laboratory data can modify and improve the patient's clinical management.

Machine Learning-Based Prediction of Hemoglobinopathies Using Complete Blood Count Data.

BACKGROUND: Hemoglobinopathies, the most common inherited blood disorder, are frequently underdiagnosed. Early identification of carriers is important for genetic counseling of couples at risk. The aim of this study was to develop and validate a novel machine learning model on a multicenter data set, covering a wide spectrum of hemoglobinopathies based on routine complete blood count (CBC) testing. METHODS: Hemoglobinopathy test results from 10 322 adults were extracted retrospectively from 8 Dutch laboratories. eXtreme Gradient Boosting (XGB) and logistic regression models were developed to differentiate negative from positive hemoglobinopathy cases, using 7 routine CBC parameters. External validation was conducted on a data set from an independent Dutch laboratory, with an additional external validation on a Spanish data set (n = 2629) specifically for differentiating thalassemia from iron deficiency anemia (IDA). RESULTS: The XGB and logistic regression models achieved an area under the receiver operating characteristic (AUROC) of 0.88 and 0.84, respectively, in distinguishing negative from positive hemoglobinopathy cases in the independent external validation set. Subclass analysis showed that the XGB model reached an AUROC of 0.97 for ß-thalassemia, 0.98 for α0-thalassemia, 0.95 for homozygous α+-thalassemia, 0.78 for heterozygous α+-thalassemia, and 0.94 for the structural hemoglobin variants Hemoglobin C, Hemoglobin D, Hemoglobin E. Both models attained AUROCs of 0.95 in differentiating IDA from thalassemia. CONCLUSIONS: Both the XGB and logistic regression model demonstrate high accuracy in predicting a broad range of hemoglobinopathies and are effective in differentiating hemoglobinopathies from IDA. Integration of these models into the laboratory information system facilitates automated hemoglobinopathy detection using routine CBC parameters.

New Born Screening of Hemoglobinopathies in a Center Tunisian Population.

Sickle cell diseases, ß-thalassemia, and other hemoglobinopathies are common in Africa. Their distribution differs from one region to another. There are higher frequencies in Western and Northern Africa. Their clinical complications presented a real public health problem in each country. For this, early treatment can improve the severity of these diseases. Hemoglobinopathies targeted by screening are associated with SCD, ß, and α thalassemia. Our study aim is to report our experience with newborn screening for hemoglobinopathy in Tunis. The 156 newborn's cord blood was collected at the time of childbirth in the center region (Farhat Hached Hôspital). We opted for hemoglobin exploration to achieve maximum efficiency and effectiveness in screening. After that, all patients suspected to have hemoglobinopathies are affected by molecular investigation. Our findings showed the presence of some hemoglobinopathies such as ß-thalassemia and α-thalassemia with the following frequencies: 12% and 0.33%. The molecular results show the presence of HBB: c.93-21G>A, IVS-I-110G>A, HBBc. -106G>A -56G>C, HBBc.404T>C, Hb Yaounde described for the first time in Tunisia and α 3,7 . In conclusion, newborn screening diagnoses neonates with different examples of hemoglobinopathies, which will be beneficial not only for the care of the child but also for genetic counseling of the potential risk's parents.

Premarital Screening is Pivotal in Reducing the Births of Babies Affected with Thalassemia Major in Iraq.

Thalassemia major is one of the health problems in Iraq, especially in Kurdistan. Pre-marriage mandatory preventive screening program was established in Kurdistan in 2008, which allowed us to study the prevalence of different hemoglobinopathies among newly married young adults in this region. A total of 1154 subjects (577 couples) attending the Koya district, premarital Health center, were screened using red cell indices. Those who had mean corpuscular volume (MCV)<80 fl and mean corpuscular hemoglobin (MCH)<27 pg had high-performance liquid chromatography and iron studies. Out of 1154 individuals that were evaluated, 183 (11.9%) had low MCV and MCH. Of the former 183 subjects, 69 (5.97%) had ß-thalassemia trait, 10 (0.86%) had δß-thalassemia trait, and no other hemoglobinopathies were recorded in our study. There was second-degree consanguinity in 4.7% of all 577 couples. In two couples, both partners had ß-thalassemia trait and both were consanguineous. Both couples decided to separate after counseling. Based on the current study, the role of the premarital screening program in decreasing the number of new thalassemia major cases among the Kurdish population is laudable. Therefore, mandatory premarital screening is advised in all parts of Iraq.

Molecular epidemiology and hematological profiles of hemoglobin variants in southern Thailand.

Data on hemoglobin (Hb) variants in southern Thailand are lacking. This study aimed to reassess the frequency of Hb variants and the clinical aspects of compound heterozygous Hb variant with other hemoglobinopathies. We enrolled 13,391 participants from ten provinces in southern Thailand during 2015-2022. Hb analysis was performed using capillary electrophoresis, and mutations in the HBA and HBB genes were identified using PCR or DNA sequencing. Hb variants were identified in 337 (2.5%) unrelated subjects. Nine ß-chain variants, namely Hb Malay (76.9%), Hb C (10.1%), Hb D-Punjab (2.9%), Hb G-Makassar (2.3%), Hb Dhonburi (2.3%), Hb Tak (1.4%), Hb J-Bangkok (1.4%), Hb New York (0.3%), and Hb Hope (0.3%), and four α-chain variants-Hb G-Georgia (HBA1) (0.9%), Hb G-Georgia (HBA2) (0.3%), Hb Q-Thailand (0.6%), and Hb St. Luke's-Thailand (0.3%)-were identified. The southern population exhibited a distinct spectrum of Hb variants compared to that observed in the populations from other areas. Several compound heterozygous genotypes were also identified. Combining Hb Malay with Hb E or high Hb F determinants did not require a blood transfusion. This study provides essential information for genetic counseling in thalassemia prevention and control programs in this region.

ß0-Thalassemia Caused by a Novel Nonsense Mutation [HBB:c.199A > T].

We report two hemoglobinopathy cases involving a novel ß-thalassemia (ß-thal) nonsense mutation, HBB:c.199A > T. One patient had Hb S/ß-thal, and a second unrelated patient had Hb D-Punjab/ß-thal. The HBB:c.199A > T mutation introduces a premature termination codon at amino acid codon 66 (AAA→TAA) in exon 2, resulting in typical high Hb A2 ß0-thal.

Autologous gene therapy for hemoglobinopathies: From bench to patient's bedside.

In recent years, a growing number of clinical trials have been initiated to evaluate gene therapy approaches for the treatment of patients with transfusion-dependent ß-thalassemia and sickle cell disease (SCD). Therapeutic modalities being assessed in these trials utilize different molecular techniques, including lentiviral vectors to add functional copies of the gene encoding the hemoglobin ß subunit in defective cells and CRISPR-Cas9, transcription activator-like effector protein nuclease, and zinc finger nuclease gene editing strategies to either directly address the underlying genetic cause of disease or induce fetal hemoglobin production by gene disruption. Here, we review the mechanisms of action of these various gene addition and gene editing approaches and describe the status of clinical trials designed to evaluate the potentially for these approaches to provide one-time functional cures to patients with transfusion-dependent ß-thalassemia and SCD.