ABSTRACT
BACKGROUND AND AIMS: To update the molecular characteristics of α-thalassemia in northeast Thailand, the molecular basis and genetic interactions of Hb H disease were examined in a large cohort of patients. MATERIALS AND METHODS: A study was done on 1,170 subjects with Hb H disease and various genetic interactions encountered during 2009-2023. Hb and DNA analyses were carried out. RESULTS: As many as 40 genotypes with several known, previously undescribed, and novel mutations were observed. These included 698 subjects (59.8 %) of Hb H disease, 357 (30.6 %) with EABart's disease, 63 (5.4 %) with EEBart's disease, 18 (1.7 %) with abnormal Hbs, 17 (1.5 %) with ß-thalassemia, and 4 (0.4 %) with EFBart's or EFABart's disease. The molecular basis of 13 subjects (1.1 %) remains unknown. The α0-thalassemia included --SEA (n = 1,139, 97.4 %) and --THAI (n = 21, 1.8 %). Two rare mutations were identified in 3 subjects (0.3 %) with --SA and --CR deletions. For α+-thalassemia, -α3.7 kb del (n = 626, 53.5 %), Hb Constant Spring (n = 415, 35.5 %), -α4.2 kb del (n = 44, 3.8 %), Hb Paksé (n = 36, 3.1 %), and Hb Q-Thailand (n = 19, 1.6 %), were detected. Ten rarer α+-thalassemia were identified, including a novel mutation, namely the Hb Chumphae (HBA2:c.32T>A). The Hb H-Lansing-Ramathibodi, Hb H-Jax, and Hb H-Chumphae are hitherto undescribed in this region. PCR-based diagnostic methods for these α-thalassemia defects were described. CONCLUSIONS: This study confirms the diverse heterogeneity and genetic interactions causing Hb H disease in northeast Thailand. The results should prove useful for laboratory diagnosis and genetic counseling of this genetic disorder in the region.
Subject(s)
Mutation , alpha-Thalassemia , Humans , alpha-Thalassemia/genetics , alpha-Thalassemia/diagnosis , Thailand , Cohort Studies , Male , Female , Hemoglobin H/genetics , Genotype , Adult , AdolescentABSTRACT
OBJECTIVE: To investigate two cases of rare pathogenic genes, initiation codon mutations in HBA2 gene, combined with Southeast Asian deletion and their family members to understand the relationship of HBA2:c.2T>C and HBA2:c.2delT mutations with clinical phenotype. METHODS: The peripheral blood of family members was obtained for blood cell analysis and capillary electrophoresis hemoglobin analysis. Gap-PCR and reverse dot blotting (RDB) were used to detect common types of mutations in É-thalassaemia gene. Sanger sequencing was used to analyze HBA1 and HBA2 gene sequence. RESULTS: Two proband genotypes were identified as --SEA/αα with HBA2:c.2T>C and --SEA/αα with HBA2:c.2delT. HBA2:c.2T>C/WT and HBA2:c.2delT/WT was detected in family members. They all presented with microcytic hypochromic anemia. CONCLUSION: When HBA2:c.2T>C and HBA2:c.2delT are heterozygous that can lead to static α-thalassemia phenotype, and when combined with mild α-thalassemia, they can lead to the clinical manifestations of hemoglobin H disease. This study provides a basis for genetic counseling.
Subject(s)
Genotype , Mutation , alpha-Thalassemia , Humans , alpha-Thalassemia/genetics , Anemia, Hypochromic/genetics , Hemoglobin A2/genetics , Hemoglobin H/genetics , Heterozygote , PhenotypeSubject(s)
Sequence Deletion , alpha-Thalassemia , Humans , alpha-Thalassemia/genetics , Brazil , Male , alpha-Globins/genetics , Child , Female , Hemoglobin H/geneticsABSTRACT
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.
Subject(s)
alpha-Thalassemia , beta-Thalassemia , Humans , beta-Thalassemia/complications , beta-Thalassemia/surgery , alpha-Thalassemia/surgery , Splenectomy , Hemoglobin H , Splenomegaly/surgery , Splenomegaly/complicationsABSTRACT
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.
Subject(s)
alpha-Thalassemia , Child , Humans , Adolescent , Child, Preschool , Hemoglobin H/genetics , Genotype , Blood TransfusionABSTRACT
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.
Subject(s)
Hemoglobins, Abnormal , alpha-Thalassemia , Pregnancy , Female , Humans , Hydrops Fetalis/diagnosis , Hydrops Fetalis/etiology , Hemoglobin H , Fetal Hemoglobin , alpha-Thalassemia/complications , alpha-Thalassemia/diagnosis , alpha-Thalassemia/genetics , Hemoglobins, Abnormal/genetics , Prenatal DiagnosisABSTRACT
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.
Subject(s)
Hemoglobinopathies , alpha-Thalassemia , beta-Thalassemia , Bayes Theorem , Genotype , Hemoglobin H/genetics , Humans , Mutation/genetics , alpha-Thalassemia/diagnosis , alpha-Thalassemia/genetics , beta-Thalassemia/geneticsABSTRACT
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.
Subject(s)
alpha-Thalassemia , Female , Hemoglobin H , Humans , Pregnancy , Retrospective Studies , alpha-Thalassemia/geneticsABSTRACT
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.
Subject(s)
Blood Group Antigens , Premature Birth , alpha-Thalassemia , Birth Weight , Female , Hemoglobin H , Humans , Infant, Newborn , Pregnancy , Premature Birth/epidemiology , Retrospective StudiesABSTRACT
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.
Subject(s)
Hemoglobins, Abnormal , alpha-Thalassemia , Female , Hemoglobin H , Humans , Hydrops Fetalis/therapy , Longitudinal Studies , Pregnancy , Prenatal Diagnosis , Retrospective Studies , Survivors , alpha-Thalassemia/therapyABSTRACT
A 60-year-old male with myelodysplastic syndrome with excess blasts-1 had unexplained microcytic hypochromic anemia. The cause of his anemia was revealed on supravital staining, hemoglobin studies and next-generation sequencing to be a novel hemizygous potentially pathogenic missense/splice site variant NM_000489.5:c.6848A>C, (p.Lys2283Thr) in exon 31 of the ATRX gene.
Subject(s)
Anemia, Hypochromic/genetics , Myelodysplastic Syndromes/genetics , X-linked Nuclear Protein/genetics , alpha-Thalassemia/diagnosis , Alternative Splicing , Anemia, Hypochromic/etiology , Fatal Outcome , Hemoglobin H/metabolism , High-Throughput Nucleotide Sequencing , Humans , Male , Middle Aged , Mutation, Missense , Myelodysplastic Syndromes/complications , alpha-Thalassemia/complications , alpha-Thalassemia/geneticsABSTRACT
The thalassemia of Hemoglobin H-Constant Spring disease (HbH-CS) is the most common type of Thalassemia in non-transfusion thalassemia. Interestingly, the clinical manifestations of the same genotype of thalassemia can be vastly different, likely due to epigenetic regulation. Here, we used microarray technology to reveal the epigenetic regulation of m6A in modifiable diseases and demonstrated a role of BCL2A1 in disease regulation. In this study, we revealed that methylating enzyme writers including METTL16, WTAP, CBLL1, RBM15B, and ZC3H13 displayed low expression and the demethylating enzyme ALKBH5, along with reader proteins including IGF2BP2 and YTHDF3 exhibited high expression. In addition, BCL2A1 was hypo-methylated and showed low expression. We also revealed that the BCL2A1 methylation level and IGF2BP2 expression were negatively correlated. Additionally, the mRNAs expression between ALKBH5 and IGF2BP2 were positively correlated. In HbH-CS, most genes were hypo-methylated. This included BCL2A1, which may play an important role in the process of red blood cell differentiation and development of HbH-CS. Moreover, the mRNA-M6A methylation status may be regulated by the demethylating enzyme ALKBH5 via IGF2BP2.
Subject(s)
Epigenesis, Genetic , RNA, Long Noncoding/genetics , RNA, Messenger/metabolism , alpha-Thalassemia/pathology , AlkB Homolog 5, RNA Demethylase/genetics , AlkB Homolog 5, RNA Demethylase/metabolism , Hemoglobin H/genetics , Hemoglobin H/metabolism , Humans , Methylation , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , alpha-Thalassemia/geneticsABSTRACT
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.
Subject(s)
Hemoglobin H/genetics , Telomere Shortening , alpha-Thalassemia/genetics , beta-Globins/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Blood Transfusion , Child , Female , Ferritins/blood , Gene Deletion , Humans , Male , Middle Aged , Severity of Illness Index , Young Adult , alpha-Thalassemia/blood , alpha-Thalassemia/diagnosis , alpha-Thalassemia/therapyABSTRACT
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.
Subject(s)
Diabetes Mellitus , alpha-Thalassemia , Adult , Diabetes Mellitus/diagnosis , Glycated Hemoglobin/analysis , Glycation End Products, Advanced , Hemoglobin H , Hemoglobin, Sickle , Humans , Serum Albumin , alpha-Thalassemia/diagnosis , Glycated Serum AlbuminSubject(s)
Enhancer Elements, Genetic , Hemoglobin H/genetics , alpha-Globins/genetics , alpha-Thalassemia/genetics , Adult , Alleles , Chromatin/genetics , Chromatin/ultrastructure , Chromosomes, Human, Pair 16/genetics , Chromosomes, Human, Pair 16/ultrastructure , Erythroblasts/pathology , Erythropoiesis , Female , Gene Deletion , Gene Expression Regulation , Genotype , Hemoglobin E/genetics , Hemoglobin H/analysis , Humans , Male , Pedigree , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Sequence Deletion , Suriname/ethnology , alpha-Globins/biosynthesis , alpha-Thalassemia/blood , beta-Globins/geneticsABSTRACT
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.
Subject(s)
Anemia, Iron-Deficiency/diagnosis , Genetic Carrier Screening/methods , Hemoglobin H/genetics , Mass Screening/methods , alpha-Thalassemia/diagnosis , Anemia, Iron-Deficiency/epidemiology , Anemia, Iron-Deficiency/genetics , Blood Cell Count , Diagnosis, Differential , Erythrocyte Indices , Female , Humans , Infant , Male , Prognosis , Thailand/epidemiology , alpha-Thalassemia/epidemiology , alpha-Thalassemia/geneticsABSTRACT
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.
Subject(s)
Anemia, Hemolytic/genetics , Hemoglobin H/genetics , Hemoglobinopathies/genetics , Hemoglobins, Abnormal/genetics , Child, Preschool , Heterozygote , Humans , MaleABSTRACT
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.