Analysis of Hematological Indices and Splenectomy Rates in 2,130 Patients with Hemoglobin H Diseases or ß-Thalassemia.

INTRODUCTION: Splenomegaly and hypersplenism are common complications of thalassemia patients due to the excessive clearance of defective red blood cells from the spleen. To date, splenectomy has been considered one of the most effective treatments for splenomegaly, reducing clinical severity among thalassemia patients. Thus, we aim to investigate the differences in splenectomy rates and hematological indices among thalassemia patients with different genotypes. METHOD: In this study, we analyzed the clinical data of thalassemia in 2,130 patients admitted to the 923rd Hospital of the People's Liberation Army from January 2006 to December 2020, and the statistical software SPSS 26.0 was applied to analyze the data. RESULT: Of the 2,130 patients with thalassemia, 265 patients underwent splenectomy. It was determined that significantly more patients with hemoglobin H (HbH) disease, a form of α-thalassemia, have undergone splenectomy than ß-thalassemia patients (20% vs. 7%). Further, HbH disease patients were diagnosed at a significantly older age than ß-thalassemia patients. CONCLUSION: The greater probability of HbH disease patients undergoing splenectomy is likely influenced by multiple factors, including their lower dependency on transfusion, leading to high spleen compensatory stress on the spleen, and the destruction of defective erythrocytes. In contrast, ß-thalassemia is clinically more severe and less tolerant of hemoglobin fluctuations. Based on these findings, clinicians are suggested to pay more attention to HbH disease patients as many of them are still under-transfused, which could lead to chronic hemolysis and more severe hepatosplenomegaly. These results might offer insight for improving the clinical management of patients with different types of thalassemia.

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

BACKGROUND: Hemoglobin (Hb) H is generally recognized as mild thalassemia, despite its actual phenotypic diversity. A disease severity scoring system to guide initiation of regular transfusion among severely affected pediatric patients has not previously been reported. METHODS: Patients with HbH were classified into transfusion-dependent thalassemia (TDT) and non-transfusion-dependent thalassemia (NTDT) as a surrogate for disease severity. Alpha-globin genotypes and relevant clinical parameters associated with TDT were identified. Univariate and multiple logistic regression analyses were performed to yield the most suitable severity scoring system. RESULTS: From 246 patients with a median age of 14.3 (interquartile range 9.9-18.4) years initially enrolled into the study, the chance of having severe disease and developing TDT was remarkable only among patients with non-deletional HbH, for whom the scoring system was developed. Univariate and multiple logistic regression analyses resulted in three retained parameters associated with TDT, ß-coefficients of which were used to develop the score. The final scoring system comprised age at diagnosis <2 years (score = 1), spleen size ≥3 cm (score = 1) and Hb at steady-state <7 (score = 4) or 7-8 g/dL (score = 3). A cutoff score ≥4 was associated with severe disease likely requiring regular transfusion (sensitivity 89.3%, specificity 81.4%), given regular transfusion resulted in maintained growth. The scoring system was validated in the second cohort of 77 non-deletional HbH, from which comparable sensitivity and specificity were obtained. CONCLUSION: The newly developed scoring system was practical and helpful to highlight severely affected pediatric non-deletional HbH patients with potential needs of regular transfusion. This can be used as a guide for optimal treatment and disease monitoring in the future.

Fetal Hemoglobin H Hydrops Fetalis: Another Three Case Reports.

We report three cases of fetalis hydrops associated with nondeletional α-thalassemia. Two cases were caused by hemoglobin (Hb) H-Quong Sz disease, and one caused by homozygous Hb Constant Spring. Fetal hydrops occurred in the late second trimester in all three cases. Our study indicates that for pregnancies at risk for fetal nondeletional Hb H disease, strict ultrasound follow-up is particularly important. Even without techniques of intrauterine transfusion treatment, early prenatal diagnosis can enable parents to make timely decisions.

Life beyond alpha-thalassaemia: We are moving forward.

In the not so distant past, pregnancy in thalassaemia patients was considered a very high risk and often not recommended. The results regarding alpha-thalassaemia and in particular haemoglobin H disease by Srimeuniwai and colleagues are very encouraging. Nowadays thalassaemic women not only become pregnant, but maternal outcome is not decreased compared to controls. Commentary on: Ake-sittipaisarn, et al. Outcomes of pregnancies complicated by haemoglobin H-Constant Spring and deletional haemoglobin H disease: A retrospective cohort study. Br J Haematol 2022;199:122-129.

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

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

Optimizing transfusion therapy for survivors of Haemoglobin Bart's hydrops fetalis syndrome: Defining the targets for haemoglobin-H fraction and "functional" haemoglobin level.

Owing to the unique pathophysiology of anaemia in haemoglobin Bart's hydrops fetalis (HBHF), a transfusion strategy based on beta-thalassemia guidelines is suboptimal for chronically transfused HBHF patients. A more aggressive transfusion aimed at reducing the proportion of non-functional HbH and improving the "functional" haemoglobin (f-Hb) can lead to reduced haemolysis and improved tissue oxygenation. However, the optimal transfusion targets for these parameters are not yet defined. In this retrospective, longitudinal study on four chronically transfused patients with HBHF, we used receiver operating characteristic curves to find a pre-transfusion f-Hb of 106 g/l and a HbH of 16.1% to be the optimal thresholds to achieve a normal soluble transferrin receptor and lactate dehydrogenase, respectively.

Detection of hemoglobin H disease by long molecule sequencing.

BACKGROUND: Hemoglobin H (Hb H) disease is a moderate-to-severe form of α-thalassemia (α-thal), and parts of patients may require intermittent transfusion therapy, especially during intercurrent illness. However, rare Hb H diseases remain undetected using routine methods being outside of the testing scope. In this study, we present an approach to detecting Hb H disease by long molecule sequencing (LMS). METHODS: A total of 206 known genotype samples were collected and carried to blind detected by LMS on the PacBio Sequel platform. Circular consensus sequencing reads were aligned to the hg19 reference genome using Free-Bayes finished LMS. LMS accuracy would be compared with routine methods, including Gap-PCR and PCR-Reverse dot blot hybridization (PCR-RDB). RESULTS: The assay could detect carriers of both deletion and point mutations. It had an overall accuracy of 100% when compared with routine methods. In addition, LMS detected six mutations based on routine methods and corrected three case results. Hb H diseases were identified using LMS, whether a common or rare genotype, a deletion or non-deletion genotype. However, two cases of Hb H disease were misdiagnosed using routine methods. CONCLUSIONS: Long molecule sequencing can be suggested as a rapid and reliable assay to detect probable carriers of hemoglobinopathies. LMS accurately identified the common and rare genotypes of Hb H disease.

Telomere shortening correlates with disease severity in hemoglobin H disease patients.

Hemoglobin H (Hb H) disease is the most significant health problem of the α-thalassemia syndromes. The Hb disease patients are categorized based on their genotype to deletional and nondeletional, with the latter genotype presents the more severe clinical symptoms. Since telomere length is an indicator of biological aging and health, we hypothesized that telomere length could reflect Hb H disease's severity. In this study, we recruited 48 deletional and 47 nondeletional Hb H disease patients, along with 109 normal controls, for telomere length assessment. The leukocyte telomere length was assessed by monochromatic multiplex real-time PCR and reported as the telomere to single-copy gene (T/S) ratio. When telomere length was adjusted for age, the analysis of covariance between the control and the two Hb H disease groups revealed no significant difference. However, the telomere shortening rate was more rapid in the nondeletional Hb H disease group than those of the control and deletional Hb H disease groups. Gender analysis found that male patients have a significantly lower T/S ratio than females in the nondeletional group but not in the control and deletional groups. In the two disease groups, the T/S ratio was not influenced by ferritin level or transfusion burden but was positively correlated with the absolute reticulocyte count.

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

OBJECTIVES: Hemoglobin A1c (HbA1c) and glycated albumin (GA) are glycemic control status indicators in patients with diabetes mellitus. Hemoglobin H (HbH) disease is a moderately severe form of α-thalassemia. Here we examine the usefulness of HbA1c and GA in monitoring glycemic control in patients with HbH disease. METHODS: HbA1c, GA, and an oral glucose tolerance test were performed in 85 patients with HbH disease and 130 healthy adults. HbA1c was measured using five methods, including two systems based on cation-exchange high-performance liquid chromatography (Variant II Turbo 2.0 and Bio-Rad D100), a capillary zone electrophoresis method (Capillarys 3 TERA), a boronate affinity HPLC method (Premier Hb9210), and an immunoassay (Cobas c501). RESULTS: Significant lower levels of HbA1c were observed in patients with HbH disease than in healthy adults. In contrast, GA showed no statistically significant differences between participants with and without HbH disease. A considerable number of diabetic patients with HbH disease would be missed if using HbA1c as a diagnostic criterion for diabetes mellitus. CONCLUSIONS: GA but not HbA1c is suitable for monitoring glycemic control in patients with HbH disease that can modify the discriminative ability of HbA1c for diagnosing diabetes.

Coinherited Hemoglobin H/Constant Spring Disease and Heterozygous Hemoglobin Tak Causing Severe Hemolytic Anemia in a Thai Boy.

Hemoglobin (Hb) H/Constant Spring disease is a common nondeletional Hb H disease, typically causing a more severe phenotype than the deletional Hb H disease counterpart. Hb Tak, resulting from a dinucleotide insertion (+AC) at codon 146 of beta-globin gene, has an increased oxygen affinity and usually presents with polycythemia. We studied a case of a 4-year-old Thai boy with a severe, early-onset anemia. To our knowledge, he is the first reported patient with Hb H/Constant Spring disease and heterozygous Hb Tak. Trio-whole-exome sequencing does not identify other genetic variants that may contribute to the severity of anemia. The observation suggests that coinherited Hb H/Constant Spring and heterozygous Hb Tak lead to severe hemolytic anemia.

Screening for Iron Deficiency Anemia in Infants in a Thalassemia-endemic Region.

Screening for iron deficiency anemia (IDA) in infants is usually carried out by hemoglobin (Hb) level and mean corpuscular volume (MCV). A coinherited thalassemia carrier may confound the diagnosis of IDA. This study aimed to characterize the hematologic parameters in infants with IDA and in thalassemia carriers, and to study the use of red cell parameters in IDA screening in a thalassemia-endemic area. Healthy infants, 6 to 12 months of age were enrolled. Blood samples were taken for complete blood count, ferritin level, Hb analysis, and polymerase chain reaction for alpha-thalassemia. IDA was defined as Hb <11.0 g/dL and ferritin <12 µg/L. Formulae calculated from red cell parameters to distinguish thalassemia carriers were analyzed. Eighty-five infants, 8.3±2.4 months of age, including 48 (56.5%) male infants were enrolled. Sixteen infants (18.8%) had IDA. There were 25 thalassemia carriers (29.4%), 1 Hb H disease, and 1 homozygous Hb E. Hb levels and MCV in the IDA and thalassemia carrier groups were significantly lower than those in the normal group. Area under the curve of Mentzer index (MCV/red blood cell count <13) to suggest thalassemia carriers was 0.867 (95% confidence interval: 0.784-0.951), and the sensitivity and specificity were 92.6% and 72.4%, respectively. In conclusion, both Hb level and Mentzer index are recommended for screening of IDA and thalassemia carriers in the population.

Genotype-phenotype correlation of HbH disease in northern Iraq.

BACKGROUND: HbH disease results from dysfunction of three, less commonly two, α-globin genes through various combinations of deletion and non-deletion mutations. Characterization of the mutations and the underlying genotypes is fundamental for proper screening and prevention of thalassaemia in any region. The aim of this study was to explore the genetic arrangements of HbH disease and to correlate the genotypes with the clinical phenotypes. METHODS: A total of 44 HbH disease patients were enrolled in this study. They were clinically and haematologically assessed. The patients were tested for 21 common α-globin gene mutations using multiplex PCR and reverse hybridization. According to the genotype, the patients were categorized into two separate sub-groups, deletion and non-deletion types HbH disease. RESULTS: Within the studied HbH disease patients, eight different α-globin gene mutations were detected in nine different genetic arrangements. The --MED and -α3.7 deletions were the two most frequently encountered mutations (37.5 and 35.2% respectively). Patients with deletion genotypes constituted 70.4%. The most common detected genotype was --MED/-α3.7 (59.1%), followed by αpoly-A1α/αpoly-A1α (13.6%). For the first time, coinheritance of two relatively mild mutations (-α3.7/ααAdana) was unpredictably detected in a 1.5 year-old child with Hb of 7.1 g/dL. CONCLUSION: The HbH disease patients' clinical characteristics were variable with no ample difference between the deletion and non-deletion types. These results can be of benefit for the screening and management of thalassaemia in this region.

Hb H Disease Diagnosed During Adolescent Pregnancy.

Hb H disease is a moderate to severe form of α-thalassemia (α-thal). Patients with Hb H disease may become symptomatic, especially during infections and pregnancy, and may require transfusions. Herein, we present a 16-year-old female with Hb H disease who was initially diagnosed during adolescent pregnancy and was found to carry the -α3.7/-(α)20.5 deletions. The relatively mild presentation of this case highlights the milder phenotypic consequences of deletional α mutations. The case describes the screening and management of pregnancy with Hb H disease. Additionally, this case demonstrates that screening of some undiagnosed inherited blood disorders is important during pregnancy.

Diagnosis and Prenatal Diagnosis in a Chinese Family Carrying the Rare α-Thalassemia Gene HBA2: c.1A>G Mutation.

The aim of this study was to identify the rare thalassemia genotype in a family and perform prenatal diagnosis (PND) on the proband's unborn child. Peripheral blood was collected from the family members for hematology analysis and capillary electrophoresis (CE) analysis. Peripheral blood and cord blood were analyzed by gap-polymerase chain reaction (gap-PCR), reverse dot-blot and Sanger sequencing for genotypes of α-thalassemia (α-thal). A heterozygous mutation, HBA2: c.1A>G, was identified in the proband and his father. Two compound heterozygous variants, HBA2: c.1A>G and the - -SEA (Southeast Asian) deletion, were revealed in the proband's unborn child. The hemoglobin (Hb) CE result of the fetal cord blood indicated the fetus had Hb H disease. We have identified a rare thalassemia mutation (HBA2: c.1A>G) in a Chinese family and enriched the rare α-thal gene pool in the Chinese population. When the patient's phenotype does not match the genotype detected by thalassemia gene detection kits, further investigation of rare genotypes should be conducted to avoid missed diagnosis or misdiagnosis, which can help guide clinical diagnosis, population screening and genetic counseling.

Nondeletional α-Thalassemia: Two New Mutations on the α2 Gene.

About 10.0% of α-thalassemia (α-thal) cases are due to point mutations, small deletions, or insertions of one or more bases on the α genes that can alter mRNA processing at the transcription, translation, or post-translation level; these cases are called nondeletional α-thalassemias (α-thal). Most occur within the domain of the α2 gene without changes in the expression of the α1 gene. We present two new frameshift mutations on the HBA2 gene, associated with a nondeletional α-thal phenotype. The probands were referred to our clinic because of persistent microcytosis and hypochromia. The molecular characterization was performed by automatic sequencing of the α-globin genes. Two new mutations were detected on the HBA2 gene; HBA2: c.85delG, p.(Ala29fs*21), and HBA2: c.268_280delCACAAGCTTCGGG, p.(His90Trpfs*9). These new mutations cause a change of the reading frame, the first on codon 28 and the second from codons 89 to 93. In the first mutation, the result is an altered amino acid sequence and a premature termination codon at position 87, while the elimination of 13 bp generates a protein of 95 residues and in this case, the premature termination codon is at position 96. These types of mutation are among the most damaging changes to the coding of a protein. Not only do they lead to changes in the length of the polypeptide, but they also vary the chemical composition, which would result in a nonfunctional protein. The importance of identifying these new mutations lies in their possible association with α0-thal, which could lead to a severe thalassemia.

α-Globin Genotypes Associated with Hb H Disease: A Report from Oman and a Review of the Literature from the Eastern Mediterranean Region.

α-Thalassemia (α-thal) is the most common autosomal recessive hemoglobinopathy. There is a vast diversity and geographical variability in underlying genotypes in Hb H (ß4) patients. Herein, we describe the genotypes found in the largest report of Omani Hb H patients. Moreover, we reviewed and summarized the literature published from the Eastern Mediterranean region. A retrospective review of all genetically confirmed Hb H disease patients diagnosed between 2007 and 2017 at Sultan Qaboos University Hospital, Muscat, Oman, was performed. Hematological parameters and clinical presentations were assessed. Both α-globin genes were screened for deletional and nondeletional mutations using a stepwise diagnostic strategy as described before. A total of 52 patients (27 females and 25 males) with a mean age of 20.6 years (range 0.23-80.0) were molecularly confirmed to carry Hb H disease. The patients had a hemoglobin (Hb) level of 9.3 g/dL (range 5.7-13.0) and mean corpuscular volume (MCV) of 58.4 fL (range 48.2-82.1). A total of eight genotype combinations were identified, with α2 polyadenylation signal mutation (polyA1) (AATAAA>AATAAG (αPA1α/αPA1α), often cited as αT-Saudiα/αT-Saudiα, being the most common (53.8%) followed by -α3.7/- -MED I (28.8%). Our cohort also included patients with combinations of αPA1 with other Hb variants: αPA1α/αPA1α with Hb S (HBB: c.20A>T) trait (n = 2), -α3.7/αPA1α (n = 2) and αcodon 19α (HBA2: c.56delG)/αPA1α (n = 1). Nondeletional Hb H disease due to the αPA1 mutation is the most common in Omanis. Molecular diagnosis is necessary for accurate confirmation of the diagnosis of α-thal, determination of underlying genotypes, follow-up and counseling.

Combined and differential effects of alpha-thalassemia and HbF-quantitative trait loci in Senegalese hydroxyurea-free children with sickle cell anemia.

BACKGROUND: Our objective was to investigate the combined and differential effects of alpha-thalassemia -3.7 kb deletion and HbF-promoting quantitative trait loci (HbF-QTL) in Senegalese hydroxyurea (HU)-free children and young adults with sickle cell anemia (SCA). PROCEDURE: Steady-state biological parameters and vaso-occlusive crises (VOC) requiring emergency admission were recorded over a 2-year period in 301 children with SCA. The age of the first hospitalized VOC was also recorded. These data were correlated with the alpha-globin and HbF-QTL genotypes. For the latter, three different genetic loci were studied (XmnI, rs7482144; BCL11A, rs1427407; and the HBS1L-MYB region, rs28384513) and a composite score was calculated, ranging from zero (none of these three polymorphisms) to six (all three polymorphisms at the homozygous state). RESULTS: A positive clinical impact of the HbF-QTL score on VOC rate, HbF, leucocytes, and C-reactive protein levels was observed only for patients without alpha-thalassemia deletion. Conversely, combination of homozygous -3.7 kb deletion with three to six HbF-QTL was associated with a higher VOC rate. The age of the first hospitalized VOC was delayed for patients with one or two alpha-thalassemia deletions and at least two HbF-QTL. CONCLUSION: Alpha-thalassemia -3.7 kb deletion and HbF-QTL are modulating factors of SCA clinical severity that interact with each other. They should be studied and interpreted together and not separately, at least in HU-free children.

Analysis of Deletional Hb H Diseases in Samples with Hb A2-Hb H and Hb A2-Hb Bart's on Capillary Electrophoresis.

The capillary electrophoresis (CE) system allows the quantification of Hb Bart's (γ4) and Hb H (ß4) that is used for screening of Hb H disease. However, Hb Bart's hydrops fetalis and Hb H are not always codetected in patients with Hb H disease. In this study, 35 samples were analyzed for the α0-thalassemia (α0-thal) [- -SEA (Southeast Asian) and - -THAI (Thailand)] deletions and the α+-thal [-α3.7 (rightward) and -α4.2 (leftward)] type deletions using real time-polymerase chain reaction (real time-PCR) with SYBR Green1 and high-resolution melting (HRM) analysis and conventional gap-PCR techniques, respectively. Results showed that 28 of 29 (96.6%) samples with the Hb A2-Hb H phenotype on CE electrophoregrams presented the genotype of - -SEA/-α3.7, while the - -SEA/-α4.2 made up the remainder. The - -SEA/-α3.7 genotype was also found in all six samples (100.0%) with Hb A2-Hb Bart's on CE electrophoregrams. Thus, for genetic counseling, prevention and control programs of Hb Bart's hydrops fetalis and Hb H disease, α-thal genotype analysis is required.

[Serum level of soluble transferrin receptor in children with hemoglobin H disease].

OBJECTIVE: To investigate the serum level of soluble transferrin receptor (sTfR) and its association with the degree of anemia in children with hemoglobin H (HbH) disease. METHODS: A total of 55 children with HbH disease were enrolled as the HbH group, and 30 healthy children were enrolled as the control group. The HbH group was further divided into a deletional HbH disease group and a non-deletional HbH disease group. A retrospective analysis was performed for hematological parameters and serum sTfR level in all groups. RESULTS: Of the 55 children with HbH disease, 39 had deletional HbH disease and 16 had non-deletional HbH disease. Compared with the control group, the deletional and non-deletional HbH disease groups had significantly lower hemoglobin (Hb), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) and a significantly higher serum level of sTfR. Compared with the deletional HbH disease group, the non-deletional HbH disease group had significantly lower red blood cell count (RBC) and Hb level and significantly higher MCV, MCH, and serum sTfR level. In children with HbH disease, serum sTfR level was negatively correlated with RBC and Hb level (r=-0.739 and -0.667 respectively, P<0.05) and positively correlated with MCV and MCH (r=0.750 and 0.434 respectively, P<0.05). CONCLUSIONS: Serum sTfR level is associated the degree of anemia in children with HbH disease, and sTfR may be a target for the treatment of HbH disease.