SUPT5H mutations associated with elevation of Hb A2 level: Identification of two novel variants and literature review

β-thalassemia is one of the most common monogenic disorders in areas of the tropics and subtropics, which represents a major familial and social burden to local people. The elevated Hb A2 level, generally specified as greater than 3.5 %, is commonly used as a high efficiency index for screening of β-thalassemia carriers. However, mutations in other genes such as GATA1 and KLF1, could also result in increased Hb A2 level. In this study, we identified two novel variants in the SUPT5H gene: a frameshift mutation (SUPT5H: c.3032_3033delTG, p.M1011Mfs*9) and a nonsense mutation (SUPT5H: c.397C > T, p.Arg133*) in two Chinese individuals. Utilizing a combination of phenotype analysis, bioinformatics analysis, and functional analysis, we deduced that these two variants modified the SUPT5H protein's structure, thereby impacting its function and consequently leading to the heightened Hb A2 level phenotype found in the carriers. Furthermore, through a comprehensive literature review, a mutation spectrum was consolidated for SUPT5H, an investigation into the genotype-phenotype correlation was conducted, and factors known to influence Hb A2 levels were identified. Based on this in-depth understanding, clinicians are better equipped to carry out large scale screenings in regions with high prevalence of β-thalassemia.

Enhancing thalassemia gene carrier identification in non-anemic populations using artificial intelligence erythrocyte morphology analysis and machine learning

BACKGROUND

Non-anemic thalassemia trait (TT) accounted for a high proportion of TT cases in South China.

OBJECTIVE

To use artificial intelligence (AI) analysis of erythrocyte morphology and machine learning (ML) to identify TT gene carriers in a non-anemic population.

METHODS

Digital morphological data from 76 TT gene carriers and 97 controls were collected. The AI technology-based Mindray MC-100i was used to quantitatively analyze the percentage of abnormal erythrocytes. Further, ML was used to construct a prediction model.

RESULTS

Non-anemic TT carriers accounted for over 60% of the TT cases. Random Forest was selected as the prediction model and named TT@Normal. The TT@Normal algorithm showed outstanding performance in the training, validation, and external validation sets and could efficiently identify TT carriers in the non-anemic population. The top three weights in the TT@Normal model were the target cells, microcytes, and teardrop cells. Elevated percentages of abnormal erythrocytes should raise a strong suspicion of being a TT gene carrier. TT@Normal could be promoted and used as a visualization and sharing tool. It is accessible through a URL link and can be used by medical staff online to predict the possibility of TT gene carriage in a non-anemic population.

CONCLUSIONS

The ML-based model TT@Normal could efficiently identify TT carriers in non-anemic people. Elevated percentages of target cells, microcytes, and teardrop cells should raise a strong suspicion of being a TT gene carrier.

Neonatal Screening for Sickle Cell Disease in Western Andalusia: Results and Lessons Learnt after 3 Years of Implementation

OBJECTIVE

 The aim of this study was to present the results obtained in the Newborn Screening Program (NSP) for sickle cell disease (SCD) in western Andalusia and the autonomous city of Ceuta in the first 3 years of implementation, and to describe the discrepancies found in the diagnosis of hemoglobinopathies between the screening method and the confirmatory tests.

STUDY DESIGN

 A descriptive and retrospective study was carried out, and the findings obtained in the newborns included in the NSP between November 2018 and December 2021 were analyzed.

RESULTS

 A total of 111,205 samples were screened by high-performance liquid chromatography (HPLC). The birth prevalence of SCD, sickle cell trait, hemoglobin C carriers, and the compound heterozygosity Hb C/β-thalassemia was 1/12,356, 1/467, 1/1,278, and 1/55,602 newborns, respectively. Although there was a correlation between the first-line HPLC screening technique (VARIANTnbs HPLC analyzer, Bio-Rad) and the confirmatory tests in most cases, major discrepancies were found in detecting carriers of G-Philadelphia, D, E, and O-Arab hemoglobin variants, with the former having an incidence of 1/10,110 and the others 1/22,241. The carrier status of Hb G-Philadelphia produced an FAD pattern on the screening method that could be mistaken as Hb D, while Hb O-Arab was identified as an FA5 pattern. Hb D was initially recognized as Hb D in two cases.

CONCLUSION

 An NSP requires at least two different combined methods in order to identify the hemoglobin variant with sufficient certainty. Furthermore, even though software solutions for HPLC suggest a pattern, it must be confirmed with another technique to obtain a correct interpretation of the chromatograms.

KEY POINTS

· The NSPs are an essential activity in preventive medicine.. · At least two different combined methods are required to correctly identify hemoglobin variants.. · Different variants can produce a similar or identical pattern by a single method..

COMBINED CENTRAL RETINAL VASCULAR OCCLUSION AS THE PRESENTING FEATURE IN β-THALASSEMIA WITH IRON DEFICIENCY ANEMIA

PURPOSE

To report a case of β-thalassemia trait with iron deficiency anemia presenting as a combined central retinal vein and artery occlusion.

METHODS

Case report. A 22-year-old woman presented with sudden-onset blurry vision in the left eye of 3-day duration.

RESULTS

Best-corrected visual acuity was 20/20 and 20/1000 in right and left eyes, respectively. Fundus examination of the left eye revealed optic disk edema, macular whitening with a cherry-red spot, markedly dilated and tortuous retinal veins, and hemorrhages both around the disk and extending into the macula and the periphery. Fundus fluorescein angiography showed delayed filling of retinal vasculature, dilated and tortuous retinal veins, and blocked fluorescence around and beyond the optic disk. Optical coherence tomography scan at presentation showed hyperreflective inner retinal layers with neurosensory detachment. Optical coherence tomography angiography showed that the vessel densities of superficial and deep capillary plexus were remarkably reduced. A diagnosis of β-thalassemia trait combined with iron deficiency anemia was made after hematologic workup. The patient was treated with a course of oral iron supplements, vasodilator (compound Xueshuantong), inhalation of a mixture of 5% carbon dioxide and 95% oxygen, and a nutritional agent (compound anisoine). Six months later, her visual acuity improved to 20/60 in the left eye with complete resolution of all clinical signs.

CONCLUSION

Combined central retinal vein and artery occlusion is a rare emergency leading to acute vision loss and can manifest in patients with β-thalassemia trait with iron deficiency anemia. Prompt diagnosis and early management is important to treat underlying systemic disorders and to prevent occurrence of a similar episode in fellow eye.

Molecular characterization of similar Hb Lepore Boston-Washington in four Chinese families using third generation sequencing

Hemoglobin (Hb) Lepore is a rare deletional δβ-thalassemia caused by the fusion between delta-beta genes, and cannot be identified by traditional thaltassemia gene testing technology. The aim of this study was to conduct molecular diagnosis and clinical analysis of Hb Lepore in four unrelated Chinese families using third generation sequencing. Decreased levels of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and an abnormal Hb band were observed in the probands of the four families. However, no common α and β-thalassemia variants were detected in the enrolled families using polymerase chain reaction-reverse dot blot hybridization based traditional thalassemia gene testing. Further third-generation sequencing revealed similar Hb Lepore-Boston-Washington variants in all the patients, which were resulted from partial coverage of the HBB and HBD globin genes, leading to the formation of a delta-beta fusion gene. Specific gap-PCR and Sanger sequencing confirmed that all the patients carried a similar Hb Lepore-Boston-Washington heterozygote. In addition, decreased levels of MCH and Hb A2 were observed in the proband's wife of family 2, an extremely rare variant of Hb Nanchang (GGT > AGT) (HBA2:c.46G > A) was identified by third-generation sequencing and further confirmed by Sanger sequencing. This present study was the first to report the similar Hb Lepore-Boston-Washington in Chinese population. By combining the utilization of Hb capillary electrophoresis and third-generation sequencing, the screening and diagnosis of Hb Lepore can be effectively enhanced.

[Study of the types of mutations of Thalassemia in Shanghai area]

OBJECTIVE

To analyze the mutations of globin genes among patients suspected for thalassemia from the Shanghai area.

METHODS

A total of 4 644 patients diagnosed at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine between June 2016 and December 2019 were selected as the study subjects. The patients were tested for common mutations associated with thalassemia gene by Gap-PCR and reverse dot blotting (RDB). Patients were suspected to harbor rare mutations based on the inconsistency between hematological phenotypes and results of common mutation detection, and were further analyzed by Gap-PCR and Sanger sequencing.

RESULTS

Among the 4 644 patients, 2 194 (47.24%) were found to carry common thalassemia mutations, among which 701 (15.09%) were α-thalassemia, 1 448 (31.18%) were β-thalassemia, and 45 (0.97%) were both α- and β-thalassemia. Forty six samples were found to harbor rare mutations, which included 17 α-globin gene and 29 β-globin gene mutations. CD77(CCC>ACC) (HBA2: c.232C>A) of the α-globin gene, NG_000007.3: g.70567_71015del449, codon 102(-A) (HBB: c.308_308delA) and IVS-Ⅱ-636 (A>G) (HBB: c.316-215A>G) of the β-globin gene were previously unreported new types of globin gene mutations.

CONCLUSION

Among the 4 644 patients, the detection rate for common thalassemia mutations was 47.24%, whilst 46 samples were detected with rare gene mutations. The type of gene mutation types were diverse in the Shanghai area. The study has provided more accurate results for genetic diagnosis and counseling.

Coinheritance of HbO Arab/β0-thalassemia with Severe Manifestation in Newborn

OBJECTIVE

 In this study, we report a Tunisian newborn boy referred for neonatal hemolytic anemia with yellowish skin and enlarged spleen due to coinheritance of hemoglobin O (HbO) Arab and β-thalassemia.

STUDY DESIGN

 Hematological parameters were collected using an automated blood cell counter. The amounts of Hb fractions were measured by capillary electrophoresis of Hb. Amplification and sequencing of the HBB gene were performed by Sanger's method.

RESULTS

 Family study and genetic analysis revealed that the proband was a carrier of two hemoglobinopathies: HbO Arab and β0-thalassemia.

CONCLUSION

 The coexistence of these two pathologies complicated the general state of the newborn boy and led to a severe anemia at birth.

KEY POINTS

· Severe neonatal anemia can be caused by hemoglobinopathy.. · Coinheritance of HbO Arab/β0-thalassemia complicated the general state of the newborn.. · Diagnosing hemoglobinopathy at an early age improves patient care..

Prevalence of thalassemia-carrier couples and fertility risk assessment

Thalassemia is a highly prevalent hematologic disease in Guizhou, China. This study aimed to determine the epidemiological characteristics of thalassemia in couples at childbearing age and assess the neonatal risk of thalassemia in this subpopulation. A cohort of 4481 couples at childbearing age were recruited for thalassemia carrier screening by both traditional hematological tests and next-generation sequencing. Of them, 1314 (14.66%) thalassemia carriers were identified, including 857 (9.76%) α-thalassemia, 391 (4.36%) β-thalassemia, and 48 (0.54%) composite α and β-thalassemia. A total of 12 α-globin gene alterations and 16 β-globin mutations were detected, including four novel thalassemia mutations. SEA was the most common α-thalassemia genotype (26.86%), CD41-42 the most common β-thalassemia genotype (36.57%), and αα/- α3.7 + CD41-42 the most common composite α- and β-thalassemia genotype (18.75%). Ethnically, the Zhuang had the highest rate of thalassemia gene carriers among the ethnic groups. Geographically, Qiannan had the highest rate of thalassemia gene carriers. In addition, 38 of the 48 couples with composite α- and β-thalassemia were high-risk thalassemia carriers, and 4 carrying the -SEA/αα gene needed fertility guidance.

Compound heterozygosity for Southeast Asian hereditary persistence of fetal hemoglobin and β0-thalassemia results in thalassemia intermedia: Pedigree analysis and genetic research in a family from South China. A case report

RATIONALE

Compound heterozygotes for deletional β-thalassemia can be difficult to diagnose due to its diverse clinical presentations and no routine screenings. This can lead to disease progression and delay in treatment.

PATIENT CONCERNS

We reported pedigree analysis and genetic research in a family with rare β-thalassemia.

DIAGNOSIS

Pedigree analysis and genetic research demonstrated that the patient was a compound heterozygote for β-thalassemia CD17/Southeast Asian hereditary persistence of fetal hemoglobin deletion, inherited from the parents. Magnetic resonance imaging T2* examination revealed severe iron deposition in the liver. Echocardiography revealed endocardial cushion defect.

INTERVENTIONS

The patient was treated with Deferasirox after receiving the final molecular genetic diagnosis. The initial once-daily dose of Deferasirox was 20 mg/kg/d.

OUTCOMES

The patient discontinued the medication three months after the first visit. Two years later, the patient visited the Department of Hepatobiliary and Pancreatic Diseases. He was recommended to undergo splenectomy after surgical repair of the congenital heart disease. However, the patient refused surgical treatment because of the economic burden.

LESSONS

We report that fetal hemoglobin is a sensitive indicator for screening large deletions of the β-globin gene, which can be effectively confirmed by the multiplex ligation-dependent probe amplification assay. In non-transfusion-dependent thalassemia patients, iron status assessment should be regularly performed, and iron chelation treatment should be initiated early. This case will provide insights for the diagnosis of rare genotypes of β-thalassemia and has important implications for genetic counseling.

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.

Splice Acceptor Mutation [HBB:c.93-2A > T] in a Patient with Hb S/β0-Thalassemia

We report a case of Hb S/β0-thalassemia (Hb S/β0-thal) in a patient who is a compound heterozygote for the Hb Sickle mutation (HBB:c.20A > T) and a mutation of the canonical splice acceptor sequence of IVS1 (AG > TG, HBB:c.93-2A > T). This is the fifth mutation involving the AG splice acceptor site of IVS1, all of which prevent normal splicing and cause β0-thal.

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

CONTEXT.—

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

OBJECTIVE.—

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

DESIGN.—

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

RESULTS.—

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

CONCLUSIONS.—

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

Peripheral blood circular RNA circ-0008102 may serve as a novel clinical biomarker in beta-thalassemia patients

Circular RNA circ-0008102 has previously been found dysregulated in β-thalassemia (β-thal) in circRNAs microarray (GSE196682 and GSE241141). Our study is aimed at identifying whether circ-0008102 could be a novel biomarker in β-thal. The peripheral blood of pediatric β-thal patients with (n = 39) or without (n = 20) blood transfusion and healthy controls (n = 30) was selected. qRT-PCR, ROC curve analysis, Spearman correlation analysis, and FISH were used to analyze clinical value of circ-0008102. qRT-PCR confirmed that circ-0008102 expression in pediatric β-thal patients without blood transfusion was significantly higher. ROC curves analysis showed that the AUC of circ-0008102 for differentiating patients without blood transfusion from patients with blood transfusion and healthy controls with an AUC of 0.733 and 0.711. Furthermore, circ-0008102 expression was positively correlated with the levels of RBC, HbF, β-globin, and γ-globin mRNA, but was negatively corrected with the levels of HbA and Cr. circ-0008102 was mainly located in the cytoplasm. circ-0008102 could induce the activation of γ-globin and negatively regulate the expression of the five highest-ranking candidate miRNAs (miR-372-3p, miR-329-5p, miR-198, miR-152-5p, and miR-627-3p) in K562 cells.

CONCLUSION

We demonstrate that peripheral blood upregulated circ-0008102 may serve as a novel clinical biomarker for pediatric β-thal without blood transfusion.

WHAT IS KNOWN

• CircRNAs are known to be involved in various human diseases, and several circRNAs are regarded as a class of promising blood-based biomarkers for detection of β-thal. • CircRNAs exert biological functions by epigenetic modification and gene expression regulation, and dysregulated circRNAs in β-thal might be involved in the induction of HbF in β-thal.

WHAT IS NEW

• Peripheral blood circ-0008102 maybe serve as a novel clinical biomarker for detection of pediatric β-thal without blood transfusion. • Circ-0008102 participates in the pathogenesis of β-thal through regulating γ-globin expression, and negatively regulates the expression of miR-372-3p, miR-329-5p, miR-198, miR-152-5p and miR-627-3p.

Enzyme-free sensitive SERS biosensor for the detection of thalassemia-associated microRNA-210 using a cascade dual-signal amplification strategy

BACKGROUND

β-thalassemia is a blood disorder caused by autosomal mutations. Gene modulation therapy to activate the γ-globin gene to induce fetal hemoglobin (HbF) synthesis has become a new option for the treatment of β-thalassemia. MicroRNA-210 (miR-210) contributes to studying the mechanism regulating γ-globin gene expression and is a potential biomarker for rapid β-thalassemia screening. Traditional miRNA detection methods perform well but necessitate complex and time-consuming miRNA sample processing. Therefore, the development of a sensitive, accurate, and simple miRNA level monitoring method is essential.

RESULTS

We have developed a non-enzymatic surface-enhanced Raman scattering (SERS) biosensor utilizing a signal cascade amplification of catalytic hairpin assembly reaction (CHA) and proximity hybridization-induced hybridization chain reaction (HCR). Au@Ag NPs were used as the SERS substrate, and methylene blue (MB)- modified DNA hairpins were used as the SERS tags. The SERS assay involved two stages: implementing the CHA-HCR cascade signal amplification strategy and conducting SERS measurements on the resulting product. The HCR was started by the products of target-triggered CHA, which formed lengthy nicked double-stranded DNA (dsDNA) on the Au@Ag NPs surface to which numerous SERS tags were attached, leading to a significant increase in the SERS signal intensity. High specificity and sensitivity for miR-210 detection was achieved by monitoring MB SERS intensity changes. The suggested SERS biosensor has a low detection limit of 5.13 fM and is capable of detecting miR-210 at concentration between 10 fM and 1.0 nM.

SIGNIFICANCE

The biosensor can detect miR-210 levels in the erythrocytes of β-thalassemia patients, enabling rapid screening for β-thalassemia and suggesting a novel approach for investigating the regulation mechanism of miR-210 on γ-globin gene expression. In the meantime, this innovative technique has the potential to detect additional miRNAs and to become an important tool for the early diagnosis of diseases and for biomedical research.

Reliability of hemoglobin A2 value as measured by the Premier Resolution system for screening of β-thalassemia carriers

OBJECTIVES

Accurate quantification of hemoglobin (Hb) A2 is vital for diagnosing β-thalassemia carriers. This study aimed to assess the precision and diagnostic utility of HbA2 measurements using the new high-performance liquid chromatography (HPLC) method, Premier Resolution, in comparison to capillary electrophoresis (CE).

METHODS

We analyzed 418 samples, previously identified as A2A by CE, using Premier Resolution-HPLC. We compared the results, established correlations, and determined an optimal HbA2 cutoff value for β-thalassemia screening. Additionally, we prospectively evaluated the chosen cutoff value in 632 samples. Mutations in the β- and α-globin genes were identified using polymerase chain reaction (PCR) techniques and DNA sequencing.

RESULTS

HbA2 levels were consistently higher with Premier Resolution, yet there was a significant correlation with CE in all samples (bias, -0.33; r, 0.991), β-thalassemia (bias, -0.27; r, 0.927), and non-β-thalassemia carriers (bias, -0.36; r, 0.928). An HbA2 cutoff value of ≥4.0 % for β-thalassemia screening achieved 100 % sensitivity and 99.6 % specificity. Further validation yielded sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 97.3 , 99.8, 97.3, 99.8, and 99.7 %, respectively. We also identified a rare β-Hb variant, Hb La Desirade [HBB:c.389C>T], associated with β-thalassemia and co-inherited with a single α-globin gene.

CONCLUSIONS

The Premier Resolution HPLC is a reliable and accurate method for routine β-thalassemia carrier screening, aligning with existing CE methods.

Point-of-Care Diagnostic Test for Beta-Thalassemia

Hemoglobin (Hb) disorders are among the most common monogenic diseases affecting nearly 7% of the world population. Among various Hb disorders, approximately 1.5% of the world population carries β-thalassemia (β-Thal), affecting 40,000 newborns every year. Early screening and a timely diagnosis are essential for β-thalassemia patients for the prevention and management of later clinical complications. However, in Africa, Southern Europe, the Middle East, and Southeast Asia, where β-thalassemia is most prevalent, the diagnosis and screening for β-thalassemia are still challenging due to the cost and logistical burden of laboratory diagnostic tests. Here, we present Gazelle, which is a paper-based microchip electrophoresis platform that enables the first point-of-care diagnostic test for β-thalassemia. We evaluated the accuracy of Gazelle for the β-Thal screening across 372 subjects in the age range of 4-63 years at Apple Diagnostics lab in Mumbai, India. Additionally, 30 blood samples were prepared to mimic β-Thal intermediate and β-Thal major samples. Gazelle-detected levels of Hb A, Hb F, and Hb A2 demonstrated high levels of correlation with the results reported through laboratory gold standard high-performance liquid chromatography (HPLC), yielding a Pearson correlation coefficient = 0.99. This ability to obtain rapid and accurate results suggests that Gazelle may be suitable for the large-scale screening and diagnosis of β-Thal.

Research on the clinical factors of cardiac iron deposition in children with beta-thalassemia major

Magnetic resonance imaging (MRI) T2* is the gold standard for detecting iron deposition in cardiac tissue, but the technique has limitations and cannot be fully performed in paediatric thalassemia patients. The aim of this study was to analyse clinical data to identify other predictors of cardiac iron deposition. A retrospective analysis was performed on 370 children with β-TM. According to the cardiac MRI results, patients were allocated to a cardiac deposition group and noncardiac deposition group. Multivariate analysis revealed that genotype and corrected QT interval were associated with cardiac iron deposition, indicating that the-β0/β0 genotype conferred greater susceptibility to cardiac iron deposition. Receiver operating characteristic curve (ROC) analysis was performed, and the area under the curve (AUC) of genotype was 0.651. The AUC for the corrected QT interval was 0.711, at a cut-off value of 418.5 ms. ROC analysis of the combined genotype and corrected QT interval showed an AUC of 0.762 with 81.3% sensitivity and 64.7% specificity. Compared to patients with the β+/β+ and β0β+ genotypes, β0β0 children with β-TM were more likely to have cardiac iron deposition.  Conclusion: The genotype and QTc interval can be used to predict cardiac iron deposition in children with β-TM who are unable to undergo MRI T2 testing.

[Research progress on differential diagnosis of thalassemia trait and iron deficiency anemia by blood erythrocyte parameters]

Thalassemia trait is an autosomal recessive genetic disease, which is a hemolytic anemia caused by disturbance of erythrocyte hemoglobin production caused by gene mutation or deletion. Iron deficiency anemia is caused by a lack of iron in the body due to an imbalance between the demand and supply of iron. The laboratory manifestations of both are microcytic hypochromic anemia, but the treatment schemes are completely different, and it is difficult to distinguish them from the results of blood count. Erythrocyte parameters can be used to establish a formula or model to differentiate them, which can achieve the purpose of early screening, early diagnosis and early treatment,preventing the occurrence of severe anemia and providing a scientific basis for the thalassemia and iron deficiency anemia prevention. This article will review the research progress of using erythrocyte parameters to distinguish thalassemia trait with iron deficiency anemia.

Multi-criteria decision making to validate performance of RBC-based formulae to screen [Formula: see text]-thalassemia trait in heterogeneous haemoglobinopathies

BACKGROUND

India has the most significant number of children with thalassemia major worldwide, and about 10,000-15,000 children with the disease are born yearly. Scaling up e-health initiatives in rural areas using a cost-effective digital tool to provide healthcare access for all sections of people remains a challenge for government or semi-governmental institutions and agencies.

METHODS

We compared the performance of a recently developed formula SCS[Formula: see text] and its web application SUSOKA with 42 discrimination formulae presently available in the literature. 6,388 samples were collected from the Postgraduate Institute of Medical Education and Research, Chandigarh, in North-Western India. Performances of the formulae were evaluated by eight different measures: sensitivity, specificity, Youden's Index, AUC-ROC, accuracy, positive predictive value, negative predictive value, and false omission rate. Three multi-criteria decision-making (MCDM) methods, TOPSIS, COPRAS, and SECA, were implemented to rank formulae by ensuring a trade-off among the eight measures.

RESULTS

MCDM methods revealed that the Shine & Lal and SCS[Formula: see text] were the best-performing formulae. Further, a modification of the SCS[Formula: see text] formula was proposed, and validation was conducted with a data set containing 939 samples collected from Nil Ratan Sircar (NRS) Medical College and Hospital, Kolkata, in Eastern India. Our two-step approach emphasized the necessity of a molecular diagnosis for a lower number of the population. SCS[Formula: see text] along with the condition MCV[Formula: see text] 80 fl was recommended for a higher heterogeneous population set. It was found that SCS[Formula: see text] can classify all BTT samples with 100% sensitivity when MCV[Formula: see text] 80 fl.

CONCLUSIONS

We addressed the issue of how to integrate the higher-ranked formulae in mass screening to ensure higher performance through the MCDM approach. In real-life practice, it is sufficient for a screening algorithm to flag a particular sample as requiring or not requiring further specific confirmatory testing. Implementing discriminate functions in routine screening programs allows early identification; consequently, the cost will decrease, and the turnaround time in everyday workflows will also increase. Our proposed two-step procedure expedites such a process. It is concluded that for mass screening of BTT in a heterogeneous set of data, SCS[Formula: see text] and its web application SUSOKA can provide 100% sensitivity when MCV[Formula: see text] 80 fl.

Mutation spectrum of thalassemia among pre-pregnant adults in the Jiangsu Province by capillary electrophoresis-based multiplex PCR assay

BACKGROUND

Thalassemia is a common genetic disorder in southwestern China, and an increasing number of cases from eastern China have been recently reported. Here, we developed a rapid, convenient, and accurate assay to evaluate the mutation spectrum of thalassemia in eastern China.

METHODS

A carrier screening assay for 61 hotspot variants among HBA1/HBA2 and HBB (OMIM: 141800, 141850, and 141900) genes was developed by SNaPshot/high-throughput ligation-dependent probe amplification (HLPA) technology. We used this assay to detect the mutation spectrum of thalassemia in individuals from eastern China and compared with the data collected from literatures focused on southern and northern China for variant distribution.

RESULTS

Among 4276 tested individuals, 2.62% (112/4276) were α-thalassemia carriers, with 90 carrying one deletion or mutation and 22 carrying two deletions. 0.40% (17/4276) were β-thalassemia carriers, and the most common variant of β-thalassemia was c.126_129delCTTT (29.41%) followed by c.316-197C>T (23.53%). The genotype distribution in our study was similar to those from southern China populations.

CONCLUSION

The Chinese population from different regions presented comparable mutation spectrum of thalassemia, and the SNaPshot/HLPA technique may serve as a capable assay for a routine genetic test in clinical practice with its accurate, rapid, and inexpensive advantage.

Identification of a Novel Variant c.163delG in HBB Gene Resulting in a Beta Null Phenotype in a Proband with Thalassemia Intermedia

A 21-year-old patient presented with a previous medical history of pallor, mild icterus, increased fatigue, low hemoglobin, and abnormal hemoglobin variant analysis with more than 70 transfusions. He was referred for genetic analysis to identify the pathogenic variations in the β-globin gene. Sanger's sequencing of the proband and his family revealed the presence of a novel frame shift variant HBB:c.163delG in a compound heterozygous state with hemoglobin E (HbE) (HBB:c.79G > A) variant. The father and the sibling of the patient were found to be normal for the HBB gene. Mother was found to be heterozygous for HbE (HBB:c.79G > A) variant. In silico analysis by Mutalyzer predicted that c.163delG variant generated a premature stop codon after seven codons, leading to a truncated protein. FoldX protein stability analysis showed a positive ΔΔG value of 45.27 kcal/mol suggesting a decrease in protein stability. HBB:c.79G > A is a known variant coding for HbE variant, which results in the reduced synthesis of β-globin chain and shows mild thalassemia. Combined effect of HBB:c.163delG and HBB:c.79G > A variants in the proband might have led to the reduced synthesis of β-globin chains resulting in a thalassemia intermedia type of clinical manifestation.

Misdiagnosis of β-Thalassemia Major Due to Chinese Gγ+(Aγδβ)0-Thalassemia Combined with β0-Thalassemia

δβ-thalassemia is a rare type of thalassemia characterized by increased Hb F levels, including mainly Chinese Gγ(Aγδβ)0-thalassemia, Yunnanese Gγ(Aγδβ)0-thalassemia, Cantonese Gγ(Aγδβ)0-thalassemia in China. Due to the low rate of δβ-thalassemia carriers, there are few reports of δβ-thalassemia combined with β-thalassemia causing β-thalassemia major. Herein, we described the combination of Chinese Gγ(Aγδβ)0-thalassemia and β-thalassemia leading to β-thalassemia major in a Chinese patient. Hemoglobin analysis was performed by capillary electrophoresis (CE). Routine genetic analysis was carried out by gap-polymerase chain reaction (Gap-PCR) and PCR and reverse dot blot (PCR-RDB). Multiple ligation-dependent probe amplification (MLPA) was used to detect the large deletion, and Gap-PCR confirmed the deletion. A CE result showed an elevated Hb F level of 98.7% and 11.7% in the proband and her mother, but the proband was diagnosed with βCD17M/βCD17M using routine genetic analysis. However, her father was heterozygous for CD17 in β-globin, and her mother was detected as SEA heterozygous. The further analysis presented that the proband had actually missed the diagnosis of Chinese Gγ(Aγδβ)0-thalassemia by MLPA and PCR-RDB. Finally, the genotype of the proband was corrected from βCD17M/βCD17M to βCD17M/βGγ(Aγδβ)0. This is the first report of Chinese Gγ(Aγδβ)0-thalassemia combined with β-thalassemia resulting in β-thalassemia major in China. Screening for δβ-thalassemia by Hb analysis could be an effective method.

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 β-thalassemia trait, 10 (0.86%) had δβ-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 β-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.

Clinical application of targeted long read sequencing in prenatal beta-thalassemia testing and genetic counseling

BACKGROUND

Beta thalassemia, related to HBB mutation and associated with elevated hemoglobin A2 (HbA2), is an important genetic hemoglobinopathy with high incidences of disease and carrier rates in Singapore. Carrier screening is essential to facilitate prenatal counseling and testing. However, when individuals with elevated HbA2 do not have an identifiable HBB disease-associated variant, there is ambiguity on risk to their offspring.

METHODS

We describe a case report of a proband with elevated HbA2, no identifiable HBB disease-associated variant, whose partner was a beta thalassemia carrier. Through clinical HBB gene sequencing, multiplex ligation-dependent probe amplification (MLPA) analysis, as well as targeted Nanopore long read sequencing of selected genes, we performed a complete analysis of HBB including the promoter region, 5'UTR and coding gene sequence, as well as evaluation for potential modifier variants and other rare structural variants.

RESULTS

This process identified that the proband was heterozygous for KLF1:c.544T>C (p.Phe182Leu), a potential functional polymorphism previously known to be associated with benign elevated HbA2 levels. The presence of disease variants in the HBB locus was excluded.

CONCLUSION

This finding provided clarity and enabled family planning for the proband and her family.

First Report of Filipino β0-Thalassemia/β-Thalassemia in a Chinese Family

A pregnant woman living in Fujian Province, southeastern China, presented due to a risk of having a baby with β-thalassemia major, during her second pregnancy, since she and her husband were suspected as β-thalassemia carriers and their affected daughter was a transfusion-dependent patient. Using the common α-thalassemia and β-thalassemia genotypes test, the pregnant woman was diagnosed as a β-thalassemia carrier with βIVS-2 - 654 (C→T)/βN genotype and her daughter had a homozygosity for IVS - 2 - 654 (C→T) mutation, however, no abnormalities were detected in her husband. SMRT identified a Filipino β0-deletion in her husband, and MLPA also revealed an unknown deletion in the HBB gene. Electrophoresis showed approximately 350 bp of the PCR product, and the β-Filipino genotype presented novel fracture fragments ranging from 5,112,884 to 5,231,358 bp, and lacked a 118,475 bp fragment relative to the wild-type sequence. The daughter was therefore diagnosed with the βIVS-2 - 654 (C→T)/βFilipino genotype. Prenatal diagnosis with umbilical cord blood at 27th week of gestation showed heteroztgosity for IVS - 2 - 654 (C→T) mutation in the fetus and continued pregnancy was recommended. In conclusion, we identified the Filipino β0-deletion in a Chinese family, from Fujian area, for the first time, during prenatal screening.

β0-Thalassemia Caused by a Novel Nonsense Mutation [c.199A > T]

We report two hemoglobinopathy cases involving a novel β-thalassemia (β-thal) nonsense mutation, HBB:c.199A > T. One patient had Hb S/β-thal, and a second unrelated patient had Hb D-Punjab/β-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 β0-thal.

Unresolved laboratory issues of the heterozygous state of β-thalassemia: a literature review

Although considered a mild clinical condition, many laboratory issues of the carrier state of β-thalassemia remain unresolved. Accurate laboratory screening of β-thalassemia traits is crucial for preventing the birth of a β-thalassemia major child. Identification of carriers in the laboratory is affected by factors that influence red cell indices and HbA2 quantification. Silent mutations and co-inheriting genetic and non-genetic factors affect red cell indices which decreases the effectiveness of the conventional approach. Similarly, the type of β mutation, co-inheriting genetic and non-genetic factors, and technical aspects, including the analytical method used and variations in the HbA2 cut-off values, affect the HbA2 results, leading to further confusion. However, the combination of mean corpuscular volume, mean corpuscular hemoglobin, and hemoglobin analysis increases the diagnostic accuracy. Diagnostic problems arising from non-genetic factors can be eliminated by carefully screening the patient's clinical history. However, issues due to certain genetic factors, such as Krüppel-like factor 1 gene mutations and α triplication still remain unresolved. Each laboratory should determine the population-specific reference ranges and be wary of machine-related variations of HbA2 levels, the prevalence of silent mutations in the community.

Thurston syndrome with thalassaemia: a rare case devising a novel molecular and phenotypic variation

A male infant presented with progressive paleness of the body since 3 months of age. On examination, the child had pallor, microcephaly with dysmorphic facies (depressed nasal bridge, low set ears, retrognathia, high arched palate and tongue hamartoma). Postaxial polydactyly in bilateral hands and feet, broad great toes, with syndactyly of left fourth and fifth toes were present. The haemogram showed severe anaemia with a microcytic hypochromic picture. High-performance liquid chromatography (HPLC) was normal. However, the parents' HPLC was suggestive of beta thalassaemia trait. Whole-exome sequencing revealed Thurston syndrome with beta-thalassaemia in homozygous pattern with a novel mutation. It is a rare genetic syndrome exclusively found in the South Asian population. Due to the rarity, identification of this syndrome is often difficult and requires awareness among clinicians. However, it is important to diagnose the disorder accurately in order to provide appropriate genetic counselling and prognostication to the parents.

Comparison of Capillary Zone Electrophoresis with High-pressure Liquid Chromatography in the Evaluation of Hemoglobinopathies

Objective

The capillary zone electrophoresis (CZE) and high-performance liquid chromatography (HPLC) methods were compared in terms of HbA2 measurement for the assessment of hemoglobinopathies.

Materials and Methods

CZE was compared with HPLC for the evaluation of patients without hemoglobinopathy (n=321), with β-thalassemia trait (n=113), and with common (HbD-Punjab, E, C, S/A, and S/S) and rare (HbS/D, O-Arap, Lepore, G-Coushata, Setif, Hamadan, Q-Iran, and H) variants (n=21). The reference range for HbA2 was determined by CZE.

Results

Among patients without hemoglobinopathy, the median (2.5th-97.5th percentiles) values were 97.4% (97.0-98.0%) and 97.5% (96.6-98.4%) for HbA (p=0.060) and 2.4% (1.6-3.0%) and 2.5% (1.6-3.1%) for HbA2 (p<0.001) by HPLC and CZE, respectively. The reference range for HbA2 was 1.6-3.1% by CZE. In the comparison of methods for HbA2, there was a constant error of 0.255 (confidence interval: 0.062-0.448) and bias of 0.10% (limit of agreement: 0.33-0.53), and higher values were obtained with CZE. A strong correlation was observed between the methods (r=0.782). Interrater agreement was almost perfect for clinical diagnosis (ϰ=0.911). The two methods detected and identified the common variants similarly. All rare variants, except HbH by HPLC and HbS/D by CZE, were detected as separate peaks by both methods.

Conclusion

The two methods were in agreement regarding the preliminary identification of β-thalassemia patients. Different Hb variants were detected by both methods but with possible methodological interference for HbA2 measurements. CZE is a reliable and simple alternative for the evaluation of hemoglobinopathies. The standardization of HbA2 measurements should be prioritized as more techniques become available in routine laboratory practice.

Mutational spectrum of HBD gene in the Chinese population: Description of 36 mutations including 11 novel variants

INTRODUCTION

Mutations in the hemoglobin subunit delta (HBD) gene (MIM#142000) are associated with decreased levels of the Hemoglobin A2 (Hb A2 ) fraction. We aimed to examine the prevalence of HBD gene mutations and summarize their characteristics in the Chinese population.

METHODS

Individuals who exhibited Hb A2 levels below 1.8%, with or without Hb A2 variant peaks, were chosen for further investigation. Hemoglobin analysis was conducted using capillary electrophoresis. Common α and β-thalassemia in China were detected using gap-PCR and reverse dot blot hybridization. The presence of HBD gene mutations was confirmed by DNA sequencing.

RESULTS

A total of 188 patients were identified as carriers of the HBD gene mutation, with a prevalence of approximately 0.46%. We discovered 36 types of mutations, 30 of which resulted in δ-globin variants, while the remaining 6 resulted in δ-thalassemia. The most common mutation was HBD:c.-127 T > C, accounting for 87.2% of δ-thalassemia cases. In addition, we identified 11 novel HBD gene mutations and found 10 cases compounded with other common thalassemias.

CONCLUSION

We observed a high prevalence of HBD gene mutations in southern China. Our findings provide a genetic basis for screening for δ-thalassemia and enrich the spectrum of HBD gene mutations.

Whole exome sequencing and rare variant association study to identify genetic modifiers, KLF1 mutations, and a novel double mutation in Thai patients with hemoglobin E/beta-thalassemia

OBJECTIVES

Clinical manifestations of patients with Hemoglobin E/beta-thalassemia vary from mild to severe phenotypes despite exhibiting the same genotype. Studies have partially identified genetic modifiers. We aimed to study the association between rare variants in protein-coding regions and clinical severity in Thai patients.

METHODS

From April to November 2018, a case-control study was conducted based on clinical information and DNA samples collected from Thai patients with hemoglobin E/beta-thalassemia over the age of four years. Cases were patients with severe symptoms, while patients with mild symptoms acted as controls. Whole exome sequencing and rare variant association study were used to analyze the data.

RESULTS

All 338 unrelated patients were classified into 165 severe and 173 mild cases. Genotypes comprised 81.4% of hemoglobin E/beta-thalassemia, 2.7% of homozygous or compound heterozygous beta-thalassemia, and 0.3% of (δβ)⁰ thalassemia Hb E while 15.7% of samples were not classified as beta-thalassemia. A novel cis heterozygotes of IVS I-7 (A > T) and codon 26 (G > A) was identified. Six genes (COL4A3, DLK1, FAM186A, PZP, THPO, and TRIM51) showed the strongest associations with severity (observed p-values of <0.05; significance lost after correction for multiplicity). Among known modifiers, KLF1 variants were found in four mild patients and one severe patient.

CONCLUSION

No rare variants were identified as contributors to the clinical heterogeneity of hemoglobin E/beta-thalassemia. KLF1 mutations are potential genetic modifiers. Studies to identify genetic factors are still important and helpful for predicting severity and developing targeted therapy.

Detecting rare thalassemia in children with anemia using third-generation sequencing

BACKGROUND

In China, conventional genetic testing methods can only detect common thalassemia variants. Accurate detection of rare thalassemia is crucial for clinical diagnosis, especially for children that need long-term blood transfusion. This study aims to explore the application value of third-generation sequencing (TGS) in the diagnosis of rare thalassemia in children with anemia.

METHODS

We enrolled 20 children with anemia, excluding from iron deficiency anemia (IDA). TGS was employed to identify both known and novel thalassemia genotypes, while sanger sequencing was used to confirm the novel mutation detected.

RESULTS

Among the 20 samples, we identified 5 cases of rare thalassemia. These included β-4.9 (hg38,Chr11:5226187-5231089) at HBB gene, α-91(HBA2:c.*91delT), αCD30(HBA2:c.91-93delGAG), Chinese Gγ+(Aγδβ)0(NG_000007.3: g .48795-127698 del 78904) and delta - 77(T > C)(HBD:c.-127T>C). Notably, the -SEA/α-91α genotype associated with severe non-deletional hemoglobin H disease (HbH disease) has not been previously reported. Patients with genotypes β654/β-4.9 and -SEA/α-91α necessitate long-term blood transfusions, and those with the -SEA/αCD30α, Chinese Gγ+(Aγδβ)0 and delta thalassemia demonstrate mild anemia.

CONCLUSIONS

TGS demonstrates promising potential as a diagnostic tool for suspected cases of rare thalassemia in children, especially those suspected to have transfusion-dependent thalassemia (TDT).

A Rare Heterozygote with a Novel IVS-Ⅱ-786 (T>A) Mutation on β-Globin Gene in a Patient with Thalassemia

BACKGROUND

Thalassemia is an inherited hemolytic blood disease, whose pathogenesis is an imbalance in the expression of hemoglobin. We report a case of a rare β-globin gene intron mutation for thalassemia patient.

METHODS

The blood routine test was performed with an automatic blood cell analyzer. Hb analysis was conducted by hemoglobin (Hb) analyzer. The common β-thalassemia and α-thalassemia gene mutations were detected by Gap-PCR and fluorescence PCR melting curve, and the rare β-thalassemia gene mutations were detected by DNA sequencing.

RESULTS

A rare heterozygous mutation of β-globin gene IVS-II-786 (T>A) was found in this case. Blood routine analysis showed the following values: Hb 92 g/L, RBC 4.1 x 1012/L, MCV 74.10 fL, MCH 22.4 pg, MCHC 303 g/L, HCT 0.304 L/L, and RET-He 22.7 pg. Hemoglobin analysis showed values of HbA2 2.2% and HbF < 2% by automatic capillary electrophoresis. The results of gene analysis and DNA sequencing showed that the β-globin gene IVS-II-786 (T>A) mutation was heterozygous.

CONCLUSIONS

The heterozygote of β-globin gene IVS-II-786 (T>A) mutation was detected for the first time, and the clinical manifestation was moderate anemia. Hemoglobin analysis indicated that the level of HbA2 was decreased. This mutation is relatively rare and easy to misdiagnose in clinical practice. It will provide a new type of evidence and guidance for genetic counseling and clinical treatment of beta thalassemia.

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.

Transient presence of stomatocytes: A clue to the diagnosis of overhydrated hereditary stomatocytosis in a child with beta-thalassemia

BACKGROUND

Overhydrated hereditary stomatocytosis (OHSt) is a rare disorder characterized by abnormalities in erythrocytic volume homeostasis. Early and accurate diagnosis is essential for appropriate management and genetic counseling.

METHODS

We present the case of a child with beta-thalassemia and a history of multiple blood transfusions. Clinical presentation, laboratory findings, and genetic testing were reviewed. Peripheral blood smear examination and genetic analysis were performed.

RESULTS

The patient was admitted with severe anemia, and peripheral blood smear examination revealed the presence of up to 50% stomatocytes. Laboratory investigations showed abnormalities in red blood cell parameters, including decreased hemoglobin levels and increased mean corpuscular volume. Genetic testing identified a heterozygous mutation in the RHAG gene, confirming the diagnosis of OHSt. The presence of stomatocytes in the peripheral blood smear was transient, correlating with episodes of hemolysis and its control.

Diagnostic Performance of 10 Mathematical Formulae for Identifying Blood Donors with Thalassemia Trait

OBJECTIVE

To compare the diagnostic performance of 10 mathematical formulae for identifying thalassemia trait in blood donors.

METHODS

Compete blood counts were conducted on peripheral blood specimens using the UniCel DxH 800 hematology analyzer. Receiver operating characteristic curves were used to evaluate the diagnostic performance of each mathematical formula.

RESULTS

In the 66 donors with thalassemia and 288 subjects with no thalassemia analyzed, donors with thalassemia trait had lower values for mean corpuscular volume and mean corpuscular hemoglobin than subjects without thalassemia donors (77 fL vs 86 fL [P < .001]; 25 pg vs 28 pg [P < .001]). The formula developed by Shine and Lal in 1977 showed the highest area under the curve value, namely, 0.9. At the cutoff value of <1812, this formula had maximum specificity of 82.35% and sensitivity of 89.58%.

CONCLUSIONS

Our data indicate that the Shine and Lal formula has remarkable diagnostic performance in identifying donors with underlying thalassemia trait.

The Spectrum of HBB Mutations among 2315 Beta Thalassemia Patients of a Reference Clinic in Tehran-Iran

Beta Thalassemia is the most prevalent and well-studied single gene disorder in Iran. Here, we investigated the spectrum of HBB gene mutations, identified among 2315 patients, referred to a reference thalassemia clinic in Tehran, on the basis of suspicion to thalassemia major or intermedia. The patients were homozygous or compound heterozygous for HBB mutations, and were referred from various Iranian provinces, during 15 years (2001- 2016). The HBB mutations were classified based on their frequency, and the result was compared to a meta-analysis of 14,293 beta thalassemia cases in the Iranian population, within the same time period. The mutation spectrum in this study contained 43 HBB mutations, compared to the 90, presented by the meta-analysis. Similar to the meta-analysis, IVSII-1 (G > A) and IVSI-5 (G > C) were the most common mutations in this study. These two comprised 62.40% of the total HBB mutant alleles in the studied population, comparable to 51.92% of that in the meta-analysis. IVSII-1 (G > A) and IVSI-5 (G > C), followed by 17 other mutations that had frequencies ranging from 0.15% to 5.44%, were among the 20 common HBB mutations in Iran and neighboring countries, according to the meta-analysis. This study provided further evidence to support the spectrum of the most common HBB mutations in the Iranian population.

Transfusion requirements and complication rate in β-thalassemia intermedia due to heterozygous β-globin gene mutation and triplicated α-globin genes

INTRODUCTION

The heterozygous condition for β-thalassemia mutation associated with an extra functional α-globin gene can produce a Thalassemia Intermedia (TI) phenotype. This genotype is the second in frequency in the French Thalassemia Registry NaThalY that prospectively collects laboratory and clinical data.

MATERIALS AND METHODS

The present report analyses transfusion needs, iron overload (ferritin, hepatic and cardiac iron concentrations), and complication rates in 45 patients included in NaThalY and presenting a heterozygous β0 or β+ -thalassemia mutation associated with a triplication at HBA locus. This cohort was compared to a cohort of patients with TI due to mutations in the beta-globin gene only and included in the French registry.

RESULTS

Patients with an extra functional α-globin gene showed a less severe anemia, lower transfusion needs and lower complication rates than those with TI related to the β-globin gene only. Nevertheless, some of them displayed complications such as cholelithiasis or extramedullary hematopoiesis. In addition, one third of the cohort needed transfusions and another third was under iron chelation.

CONCLUSION

The genotype associating a heterozygous β0 or β+ -thalassemia mutation with a triplication at HBA locus should be accurately diagnosed as it could lead to symptomatic anemia and to potential iron overload and iron-related complications even in patients with no transfusion need.

A large cohort of deletional high hemoglobin F determinants in Thailand: A molecular revisited and identification of a novel mutation

BACKGROUND AND AIMS

High hemoglobin F determinants can be classified into hereditary persistence of fetal hemoglobin (HPFH) and δβ-thalassemia with different phenotype. We report the molecular basis and hematological features in a large cohort of deletional high Hb F determinants in Thailand.

MATERIALS AND METHODS

Subjects (n = 28,177) encountered during 2015-2022 were reviewed, and those with phenotypically suspected of having high Hb F determinants were selected. Combined PCR, multiplex ligation-dependent probe amplification, next-generation sequencing, and DNA sequencing were used to identify the mutations.

RESULTS

Among 28,177 subjects investigated, 300 (1.06 %) were found to carry deletional high Hb F determinants in a total of 302 alleles, including heterozygote, compound heterozygote with β-hemoglobinopathies, and homozygote. DNA analysis identified eight different DNA deletions, including δβ0-thalassemia (12.6 kb deletion) (73.8 %), HPFH-6 (14.9 %), Indian deletion-inversion Aγδβ0-thalassemia (3.6 %), Thai deletion-inversion-insertion Aγδβ0-thalassemia (3.0 %), SEA-HPFH (3.0 %), Chinese Aγδβ0-thalassemia (1.0 %), Thai δβ0-thalassemia (11.3 kb deletion) (0.3 %), and a novel δβ0-thalassemia (137.1 kb deletion) (0.3 %). In addition, three novel genetic interactions, including Chinese Aγδβ0-thalassemia/Hb E, δβ0-thalassemia/Indian deletion-inversion Aγδβ0-thalassemia, and homozygous δβ0-thalassemia were found. Hematological features and Hb analysis results of 20 different genotypes were recorded. Multiplex gap-PCR assays for detection of these genetic determinants were described.

CONCLUSIONS

Deletional high Hb F determinants are common and heterogeneous in Thailand. Data on the prevalence, molecular spectrum, phenotypic expression, and complex interactions of these genetic determinants should prove useful in the study and a prevention and control program of hemoglobinopathies in the region.

Application of real-time PCR-based multicolor melting curve with automatic analysis system in pregestational and prenatal thalassemia diagnoses

BACKGROUND

To evaluate the value of the real-time PCR-based multicolor melting curve analysis (MMCA) with an automatic analysis system used in a mass thalassemia screening and prenatal diagnosis program.

METHODS

A total of 18,912 peripheral blood samples from 9456 couples and 1150 prenatal samples were detected by MMCA assay. All prenatal samples were also tested by a conventional method. Samples with unknown melting peaks, unusual peak height ratios between a wild allele and a mutant allele, or a discordant phenotype-genotype match were further studied by using multiplex ligation-dependent probe amplification (MLPA) or Sanger sequencing. All MMCA results were automatically analyzed and manually checked. The consistency between MMCA assay and conventional methods among prenatal samples was investigated.

RESULTS

Except for initiation codon (T > G) (HBB:c.2T > G), all genotypes of thalassemia inside the scope of conventional methods were detected by MMCA assay. Additionally, 27 carriers with 10 rare HBB variants, 13 with α fusion gene, 1 with a rare deletion in α globin gene, and 1 with rare HBA variant were detected by using MMCA assay.

CONCLUSION

MMCA can be an alternative approach used in routine thalassemia carrier screening and prenatal diagnosis for its high throughput, sufficient stability, low cost, and easy operation.

Molecular spectrum and prevalence of thalassemia investigated by third-generation sequencing in the Dongguan region of Guangdong Province, Southern China

BACKGROUND

PCR, Sanger sequencing and NGS are often employed for carrier screening of thalassemia but all of these methods have limitations. In this study, we evaluated a new third-generation sequencing-based approach termed comprehensive analysis of thalassemia alleles (CATSA) to explore the prevalence of thalassemia in the Dongguan region of southern China.

METHODS

19,932 subjects were recruited for thalassemia screening and hemoglobin testing was performed for each of them. Routine PCR was performed for all the hemoglobin testing-positive subjects and CATSA was conducted for randomly selected subjects from hemoglobin testing-positive and negative subjects.

RESULTS

In the 2716 subjects tested both by PCR and CATSA, 2569 had the same results and 147 had discordant results between the two methods. Sanger sequencing, specially designed PCR and MLPA confirmed the results of CATSA were all correct. In total, CATSA correctly detected 787 subjects with variants while routine PCR correctly detected 640 subjects with variants. CATSA yielded a 5.42% (147 of 2716) increment compared with routine PCR. In the 447 hemoglobin testing-negative subjects, CATSA identified pathogenic variants in 12 subjects. Moreover, CATSA identified a novel deletion (chr16:171262-202032) in the α-globin gene cluster. As a result, the deduced carrier frequency of α-thalassemia,β-thalassemia and α-/β-thalassemia was 5.62%, 3.85% and 0.93%, respectively.

CONCLUSIONS

Our study demonstrated CATSA was a more comprehensive and precise approach than the routine PCR in a large scale of samples, which is highly beneficial for carrier screening of thalassemia. It provided a broader molecular spectrum of hemoglobinopathies and a better basis for a control program in Dongguan region.

The comprehensive analysis of thalassemia alleles (CATSA) based on single-molecule real-time technology (SMRT) is a more powerful strategy in the diagnosis of thalassemia caused by rare variants

Thalassemia is one of the most widely distributed monogenic disorders in the world and affects the largest number of people. It can manifest a wide spectrum of phenotypes from asymptomatic to fatal, which is associated with the degree of imbalance between α- and β-globin chains. Therefore, individuals with different genotypes could present with a similar phenotype. Genetic analysis is always needed to make a correct diagnosis. However, routine genetic analysis of thalassemia used in the Chinese population identifies only 23 common variants, resulting in many cases undiagnosed or being misdiagnosed. In this study, we applied a long-read sequencing-based approach termed comprehensive analysis of thalassemia alleles (CATSA) to 30 subjects whose hematologic screening results could not be explained by the routine genetic test results. The identification of additional variants and the correction of genotypes allowed the interpretation of the clinical phenotype in 24 subjects, which have been confirmed to be correct by independent experiments. Moreover, we identified a novel 8.4-kb deletion containing the entire HBB and HBD genes as well as part of the HBBP1 gene, expanding the genotype spectrum of β-thalassemia. CATSA showed a great advantage over other genetic tests in the diagnosis of thalassemia caused by rare variants.

Busulfan-Based and Treosulfan-Based Myeloablative Conditioning for Allogeneic Transplantation in Children with Thalassemia Major: a Single-Center Experience From Southern Turkey

OBJECTIVES

Allogeneic hematopoietic stem cell transplant is the only curative treatment for patients with transfusion-dependent thalassemia major. In recent years, a number of novel approaches have improved patient outcomes and quality of life by minimizing the toxicity of conditioning regimens. The objective of this study was to compare the role of treosulfan- and busulfan-based conditioning in transfusion-dependent thalassemia.

MATERIALS AND METHODS

Data were collected retrospectively on 121 children with beta thalassemia major who underwent hematopoietic stem cell transplant using treosulfan-based (n = 37) or busulfan-based (n = 84) conditioning regimens between 2012 and 2022.

RESULTS

Two-year overall survival was 87.5% in the busulfan-based conditioning group and 91.1% in the treosulfan-based conditioning group.The group given the busulfan regimen compared with treosulfan regimen had significantly increased number of side effects (58.3% vs 21.6%, respectively; P < .001). When the busulfan-based regimen by level was evaluated, we observed no significant differences between the frequency of side effects according to drug serum levels. In addition, no significant differences were shown between the 2 regimen groups for cumulative incidence of acute and chronic graft-versus-host disease.

CONCLUSIONS

The safety and effectiveness of a treosulfan-based myeloablative conditioning regimen has been confirmed by ourretrospective investigation of pediatric patients with beta thalassemia.