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Alpha-thalassemia is an inherited blood disorder caused by impaired α-globin chain production, leading to anemia and other complications. Hemoglobin H (HbH) disease is caused by a combination of mutations generally affecting the expression of three of four α-globin alleles; disease severity is highly heterogeneous, largely driven by genotype. Notably, non-deletional mutations cause a greater degree of ineffective erythropoiesis and hemolysis, higher transfusion burden, and increased complication risks versus deletional mutations. There are limited treatment options for HbH disease, and effective therapies are needed. This review discusses the pathophysiology of HbH disease, current management strategies, unmet needs, and emerging treatment options., (© 2024 The Author(s). American Journal of Hematology published by Wiley Periodicals LLC.)

Abnormality of three α-globin genes, either deletion or point mutation results in symptomatic Hemoglobin H (HbH) phenotype. Most of such cases of α-globin defects are inherited from the parents, de-novo cases are exceedingly rare. Herein, a case of HbH is reported where the proband inherited one α-globin gene with a point mutation (α Evanston ) from the mother. This was associated with large de-novo deletion of chromosome 16p13.3 resulting in α-thalassemia and mental retardation (ATR-16) syndrome. This deletion also encompassed two α-globin genes from chromosome 16, eventually leading to --/αα Evanston genotype, explaining the clinical presentation of the proband. The challenges in screening of such cases and confirming the molecular diagnosis along with the mode of inheritance has been discussed., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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 β-thalassemia, and 4 (0.4 %) with EFBart's or EFABart's disease. The molecular basis of 13 subjects (1.1 %) remains unknown. The α 0 -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, -α 3.7 kb del (n = 626, 53.5 %), Hb Constant Spring (n = 415, 35.5 %), -α 4.2 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Hemoglobin (Hb) H disease presents a wide range of clinical phenotypes, from asymptomatic to severe forms, depending on significant genetic heterogeneity. This is the first report of clinical and hematological features of the nondeletional HbH disease caused by -- CR /α CS α. A baby was born to a father and a mother with -- CR and α CS α carriers, respectively. She had severe symptomatic hypochromic microcytic anemia at 2 months of age with Hb 7.8 g/dL, packed cell volume (PCV) 0.27 L/L, mean corpuscular volume (MCV) 64.3 fL, and mean corpuscular Hb (MCH) 18.3 pg. The Hb analysis using capillary electrophoresis (CE) showed Hb Bart's, HbH, and Hb CS peaks at 17.1%, 2.2%, and 1.6%, respectively. A better understanding of a patient's clinical and hematological features with -- CR /α CS α is useful for hemoglobinopathy counseling for the national thalassemia controlling program.

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 ɑ-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.

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, β-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., (© 2023 Japan Pediatric Society.)

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., (© 2022 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

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 m 6 A 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-M 6 A methylation status may be regulated by the demethylating enzyme ALKBH5 via IGF2BP2., (© 2021. The Author(s).)

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., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

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., (Copyright © 2021 Elsevier Inc. All rights reserved.)

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.

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 -α 3.7 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 /-α 3.7 (59.1%), followed by α poly-A1 α/α poly-A1 α (13.6%). For the first time, coinheritance of two relatively mild mutations (-α 3.7 /αα Adana ) 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.

Objectives: We analyzed hemoglobin (Hb) levels and degree of anemia in relation to genotype in patients with hemoglobin H (Hb H) disease, thereby providing a scientific basis for the prevention and treatment of Hb H disease in the Guangxi region of China., Methods: Hb analysis was conducted in 615 patients using high performance liquid chromatography. Seven α-thalassemia and 17 β-thalassemia genotypes commonly found in the Chinese population were detected by Gap-polymerase chain reaction and reverse dot hybridization. Multiple ligation-dependent probe amplification and sequencing were used to detect α-globin gene., Results: On analyzing the degree of anemia, we found that the proportion of severe and moderate anemia was the highest among cases with - SEA /α CS α genotype, followed by - SEA /α QS α. When Hb H disease was present in combination with β-thalassemia, the clinical symptoms of most patients were milder than those with simple Hb H disease., Conclusion: The clinical manifestations of various types of Hb H disease are heterogeneous; the Hb levels of patients with deletional Hb H are generally higher than those with non-deletional Hb H ( P < 0.05). In-depth knowledge of the gene mutation spectrum of thalassemia in Guangxi can provide a basis for genetic counseling of couples and enable prenatal diagnosis.

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 -α 3.7 /-(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.

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 (β4) 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) (AATAA A >AATAA G (α PA1 α/α PA1 α), often cited as α T-Saudi α/α T-Saudi α, being the most common (53.8%) followed by -α 3.7 /- - MED I (28.8%). Our cohort also included patients with combinations of α PA1 with other Hb variants: α PA1 α/α PA1 α with Hb S ( HBB : c.20A>T) trait ( n  = 2), -α 3.7 /α PA1 α ( n  = 2) and α codon 19 α ( HBA2 : c.56delG)/α PA1 α ( n  = 1). Nondeletional Hb H disease due to the α PA1 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.

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&#95;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 α 0 -thal, which could lead to a severe thalassemia.

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.

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., (© 2019 Wiley Periodicals, Inc.)

The capillary electrophoresis (CE) system allows the quantification of Hb Bart's (γ4) and Hb H (β4) 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 α 0 -thalassemia (α 0 -thal) [- - SEA (Southeast Asian) and - - THAI (Thailand)] deletions and the α + -thal [-α 3.7 (rightward) and -α 4.2 (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 A 2 -Hb H phenotype on CE electrophoregrams presented the genotype of - - SEA /-α 3.7 , while the - - SEA /-α 4.2 made up the remainder. The - - SEA /-α 3.7 genotype was also found in all six samples (100.0%) with Hb A 2 -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.

Objective: α-Thalassemia, one of the most common genetic diseases, is caused by deletions or point mutations affecting one to four α-globin genes. Molecular diagnosis is important to prevent the most severe forms of the disease. However, the diagnosis of α-thalassemia is complex due to a high variability of the genetic defects involved, with over 250 described mutations. We summarize herein the findings of genetic analyses of DNA samples referred to our laboratory for the molecular diagnosis of α-thalassemia, along with a detailed clinical description., Methods: We utilized a diagnostic algorithm including Gap-PCR, to detect known deletions, followed by sequencing of the α-globin gene, to identify known and novel point mutations, and multiplex ligation-dependent probe amplification (MLPA) for the diagnosis of rare or novel deletions., Results: α-Thalassemia was diagnosed in 662 of 975 samples referred to our laboratory. Most commonly found were deletions (75.3%, including two novel deletions previously described by us); point mutations comprised 25.4% of the cases, including five novel mutations. Our population included mostly Jews (of Ashkenazi and Sephardic origin) and Muslim Arabs, who presented with a higher rate of point mutations and hemoglobin H disease. Overall, we detected 53 different genotype combinations causing a spectrum of clinical phenotypes, from asymptomatic to severe anemia., Conclusion: Our work constitutes the largest group of patients with α-thalassemia originating in the Mediterranean whose clinical characteristics and molecular basis have been determined. We suggest a diagnostic algorithm that leads to an accurate molecular diagnosis in multiethnic populations., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Thalassemia is the most common monogenic disease, with the highest incidence in Guangxi Zhuang Autonomous Region, People's Republic of China (PRC). The blood test result was not consistent with α-globin gene testing in one of the patients during daily screening. It was confirmed that there were multiple mutations at the α2-globin gene polyadenylation (polyA) signal site: HBA2: c.*64(T>C), HBA2: c.*68(A>C), HBA2: c.*71(G>A), HBA2: c.*74(C>A), HBA2: c.*82(G>A), HBA2: c.*92(A>G) and HBA2: c.*98(T>C) and compound - - SEA /αα by sequencing of the HBA1 and HBA2 genes of the proband and core family members. After that, we found a further two cases of unrelated patients with this type of mutation. The mutation is not an accidental phenomenon, and likely to occur with a considerable incidence in Guangxi Zhuang Autonomous Region, PRC. We analyzed the hematological manifestations of this type of thalassemia and showed that it was a Hb H (β4) disease caused by rare mutations. We suggest that it is essential to pay attention to this mutation during future clinical diagnoses and genetic counseling of patients.

Background: Sickle cell anemia (SCA) patients exhibit sub-phenotypes associated to hemolysis and vaso-occlusion. The disease has a chronic inflammatory nature that has been also associated to alterations in the lipid profile. This study aims to analyze hematological and biochemical parameters to provide knowledge about the SCA sub-phenotypes previously described and suggest a dyslipidemic sub-phenotype., Methods: A cross-sectional study was conducted from 2013 to 2014, and 99 SCA patients in steady state were enrolled. We assessed correlations and associations with hematological and biochemical data and investigated the co-inheritance of -α 3.7Kb -thalassemia (-α 3.7Kb -thal). Correlation analyses were performed using Spearman and Pearson coefficient. The median of quantitative variables between two groups was compared using t-test and Mann-Whitney. P-values <0.05 were considered statistically significant., Results: We found significant association of high lactate dehydrogenase levels with decreased red blood cell count and hematocrit as well as high levels of total and indirect bilirubin. SCA patients with low nitric oxide metabolites had high total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol and reduced very low-density cholesterol, triglycerides, direct bilirubin level and reticulocyte counts. In SCA patients with high-density lipoprotein cholesterol greater than 40 mg/dL, we observed increased red blood cell count, hemoglobin, hematocrit, and fetal hemoglobin and decreased nitric oxide metabolites levels. The presence of -α 3.7Kb -thal was associated with high red blood cell count and low mean corpuscular volume, mean corpuscular hemoglobin, platelet count and total and indirect bilirubin levels., Conclusions: Our results provide additional information about the association between biomarkers and co-inheritance of -α 3.7Kb -thal in SCA, and suggest the role of dyslipidemia and nitric oxide metabolites in the characterization of this sub-phenotype.

The 2.4 kb (or -α(2.4)) deletion in the α-globin gene cluster (NG&#95;000006.1) is an α(+)-thalassemia (α(+)-thal) allele. The molecular basis of -α(2.4) is a deletion from 36860 to 39251 of the α-globin gene cluster. It was reported by three research groups in 2005, 2012 and 2014, respectively. In routine thalassemia screening studies by this research group, we found an individual with the -α(2.4)/αα genotype and an Hb H (β4) disease patient whose genotype was - -(SEA)/-α(2.4). Samples from the parents of the carrier of the -α(2.4)/αα genotype were collected to perform pedigree analysis, and the proband's mother's genotype was diagnosed to be - -(SEA)/-α(2.4). The research revealed that the -α(2.4) allele exists in the population of southern Guangxi, People's Republic of China.

Background & Objectives: Alpha-thalassaemias are genetic disorders with high prevalence in northern Thailand. However, common genotypes and current data on the prevalence of α-thalassaemias have not been reported in this region. Therefore, the objective of the present study was to determine the prevalence of α-thalassaemia genotypes in pregnant women in northern Thailand., Methods: Genomic DNA was extracted from blood samples of pregnant women who came to Maharaj Nakorn Chiang Mai University Hospital during July 2009 to 2010. The common deletion and point mutation genotypes of α-thalassaemia were evaluated by gap- polymerase chain reaction (PCR) and PCR with restriction fragment length polymorphism (RFLP)., Results: Genotypes of 638 pregnant women were: 409 samples (64.11%) being normal subjects (αα/αα) and 229 samples (35.89%) with α-thalassaemias. these 229 samples could be classified into deletional HbH disease (--SEA/-α3.7) for 18 samples (2.82%); heterozygous α0-thalassaemia --SEA type (--SEA/αα)) for 78 (12.23%); heterozygous α+-thalassaemia - α3.7 type (-α3.7/αα) for 99 (15.52%); homozygous α+-thalassaemia - α3.7 type (-α3.7/- α3.7) for five (0.78%); heterozygous α+-thalassaemia - α4.2 type (-α4.2/αα) for two (0.31%); and heterozygous HbCS (αCSα/αα) for 27 (4.23%) cases., Interpretation & Conclusions: The prevalence of α-thalassaemias in pregnant women in northern Thailand was high. This finding supports the implementation of the prevention and control of this common genetic disorder by screening for α-thalassaemia genotypes.

Most people with Hb H disease live normal lives; however, a minority of cases requires lifelong regular transfusions. An atypical form of nondeletional Hb H disease was reported in a Thai boy, characterized by severe persistent hemolytic anemia since the age of 2 months. Molecular diagnosis revealed the apparent compound heterozygosity for the Southeast Asian (- -(SEA)) and α2 polyadenylation (polyA) signal (AATAAA>AATA- -) deletions. The proband was successfully treated with allogeneic hematopoietic stem cell transplantation (HSCT). Accurate phenotypic and genotypic diagnosis in atypically severe Hb H disease is helpful for the understanding of its pathophysiology, the institution of appropriate management, and provision of genetic counseling and prenatal diagnosis. Hematopoietic stem cell transplantation is a potentially curative treatment option for this severe α-thalassemia (α-thal) syndrome.

HbH disease had been introduced as a mild anemia disease. It recently has become the most challenging hemoglobinopathy due to the increasingly described genotype patterns and very variable phenotypic presentations in different ethnics. Phenotypic severity of HbH syndrome is not simply related to the degree of α-globin deficiency and being influenced by several environmental and/or genetic factors. Hence, more investigation needs to identify factors like other genetic loci linked and/or unlinked to the α-globin genes affecting molecular mechanisms that influence clinical expression of HbH disease. Altogether, the complicated pathophysiology of HbH disease makes it to be known as a poorly understood syndrome. It may offer the hypothesis that it is a multifactorial disease, which needs to be investigated by more comprehensive genetic approach like genome wide association studies (GWAS) looking for genetic variants. Moreover, extended haplotype analysis to find out probable specific association between haplotypes of modifier genes and disease severity in patients with a specific HbH genotype may be a key point. In this review, we aim to provide important information regarding phenotypic presentation of different genotypes that have been described worldwide. It may help geneticists regarding challenging health care aspects of HbH disease in a specific ethnic., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Introduction: Among hemoglobin (Hb) H disease cases diagnosed by DNA testing in our hemoglobinopathy laboratory, we have noted instances of unreported Hb H from high-performance liquid chromatography (HPLC) results of referring laboratories., Methods: To characterize these issues, we identified all cases of genotypic Hb H disease diagnosed in our laboratory. HPLC chromatograms were reviewed to determine the presence and retention time of the Hb H peak., Results: Hemoglobin H was not reported in 24.2% of patients (23 of 95) with genotypic Hb H disease. The characteristic prerun peak of Hb H was present on review of all eight Variant or Variant II β-thalassemia short-program chromatograms. Elevated Hb F (≥3%) was reported in 14 cases. The Hb H peak was found in the Hb F window in 11 dual program cases. The incorrect identification of Hb H as elevated Hb F resulted in two testing referrals for 'δβ-thalassemia'., Conclusions: Hemoglobin H may go unreported due to failure to examine for or recognize its peak on Variant or Variant II β-thalassemia short-program chromatograms. Elution of Hb H in the Hb F window resulted in misidentification of Hb H for Hb F and may indicate a Variant II HbA2 /HbA1C program software error. Our findings highlight the need for careful chromatogram inspection and clinical correlation in the diagnosis of Hb H disease., (© 2015 John Wiley & Sons Ltd.)

Objective: To investigate the genotypes and clinical features of children with HbH disease in Guangxi Zhuang Autonomous Region, China., Methods: A total of 595 children from Guangxi were recruited. Single-tube multiplex polymerase chain reaction combined with agarose gel electrophoresis, as well as reverse dot blotting, were performed to detect the three α-globin gene deletion mutations (--(SEA), -α(3.7), and -α(4.2)) and three non-deletion mutations (Hb Westmead, Hb Constant Spring, and Hb Quong Sze) which are common in the Chinese population., Results: Among the 595 cases, five common genotypes were identified, which were --(SEA)/-α(3.7) (232 cases), --(SEA)/α(CS)α (174 cases), --(SEA)/-α(4.2) (122 cases), --(SEA)/α(WS)α (35 cases), and --(SEA)/α(QS)α (24 cases). The genotype of THAI deletion associated with α-thalassemia-2 was detected in eight cases. Six β-mutations including CD41-42, CD17-28, CD26, IVS-II-654, IVS-I-1, and CD27-28 were identified in 23 cases. All children with HbH disease had microcytic hypochromic anemia; children with HbH-CS disease had the most severe anemia, and those with HbH-WS disease had the mildest anemia., Conclusions: Deletional HbH disease is the main type in children with HbH disease in Guangxi, and some patients also have mild beta-thalassemia. Non-deletional HbH disease shows more severe phenotype than deletional HbH disease.

Objective: The spectrum of α-thalassemias correlates well with the number of affected α-globin genes. Additionally, combinations of the several non-deletional types of mutations with a large trans deletion comprising the 2 α-globin genes have an impact on the clinical severity. The objective of this study was to analyze the hematological and molecular data of 35 patients with Hb H disease from a single center in order to identify the genotypes of Hb H disease and genotype-phenotype correlations., Materials and Methods: Herein, we report the hematological and mutational spectrum of patients with Hb H disease (n=35). Additionally, genotypes of α-gene mutations of 78 individuals, who were referred to our institution for α-gene screening, were analyzed., Results: Supporting the previous data from Turkey, -α3.7 was the most common mutation among patients with Hb H disease (62.8%) and in the other 78 subjects (39.7%). Of the patients with Hb H disease, the most common genotypes were -α3.7/--20.5, -α3.7/--26.5, and -α3.7/--17.5 in 10 (28.6%), 6 (17.1%), and 6 (17.1%) patients, respectively. Another small deletion, -4.2 alpha, and several non-deletional types of α-gene mutations, namely α (-5nt): IVS-I donor site (GAG.GTG.AGG->GAG.G-----); α (PA-2): AATAAA>AATGGA, and α (cd59): GGC->GAC, were found to be associated with Hb H disease when present at trans loci of one of the large deletions given above. The combinations consisting of 1 non-deletional and 1 of the large deletional types of mutations (αTα/--) at trans loci were found to result in a more severe phenotype compared to the genotypes composed of 1 small trans deletion of a large deletion (-α/--). The combination of α (Cd59) and -- in trans was associated with severe phenotype and the disease was associated with an increase in Hb Bart's level with null Hb H. In spite of the presence of 2 intact α-globin genes, homozygosity for PA-2 mutation resulted in severe Hb H disease., Conclusion: This study indicated that Hb H disease is not rare in Turkey and its genotype is quite heterogeneous.

α-Thalassemia (α-thal) is a common genetic disorder in Iran and many parts of the world. Genetic defects in the α-globin gene cluster can result in α-thal that may develop into a clinical phenotype varying from almost asymptomatic to a lethal hemolytic anemia. Loss of one functional α gene, indicated as heterozygous α(+)-thal, shows minor hematological abnormalities. Homozygosity for α(+)- or heterozygosity for α(0)-thal have more severe hematological abnormalities due to a markedly reduced α chain output. At the molecular level, the absence of three α-globin genes resulting from the compound heterozygous state for α(0)- and α(+)-thal, lead to Hb H disease. Here we present a 21 nucleotide (nt) duplication consisting of six amino acids and 3 bp of intronic sequence at the exon-intron boundary, in both the α-globin genes, detected by direct DNA sequencing. This duplication was identified in three patients originating from two different Iranian ethnic groups and one Arab during more than 12 years. The clinical presentation of these individuals varies widely from a mild asymptomatic anemia (heterozygote in α1-globin gene) to a severely anemic state, diagnosed as an Hb H individual requiring blood transfusion (duplication on the α2-globin gene in combination with the - -(MED) double α-globin gene deletion). The third individual, who was homozygous for this nt duplication on the α1-globin gene, showed severe hypochromic microcytic anemia and splenomegaly. In the last decade, numerous α-globin mutations have demonstrated the necessity of prenatal diagnosis (PND) for α-thal, and this study has contributed another mutation as important enough that needs to be considered.

Hb Constant Spring (Hb CS; HBA2: c.427T > C) is an unstable hemoglobin (Hb) variant that results from a nucleotide substitution at the termination codon of the α2-globin gene. Compound heterozygosity for α(0)-thalassemia (α(0)-thal) and Hb CS (- -(SEA)/α(CS)α) results in Hb H/Hb CS disease, which is generally characterized with mild hemolytic anemia, jaundice, and splenomegaly. Here, we describe one case with Hb H/Hb CS disease that presented with fetal anemia and fetal hydrops, known as Hb H (β4) hydrops fetalis. This is the first report of fetal hydrops caused by association of the - -(SEA) deletion and the α(CS)α mutation. Our study highlights the significance of watchful observation using a serial ultrasound method and care of pregnant women who have fetuses found to carry Hb H/Hb CS disease during pregnancy, to guard against the occurrence of fetal hydrops.

A previously unknown α(0) deletion, designated - -(DANE), was found in three generations of a Danish family of Palestinian origin. Six patients were heterozygous and three patients had deletional Hb H (β4) disease with a compound heterozygosity for the common -α(3.7) (rightward) deletion. Multiplex ligation-dependent probe amplification (MLPA) supplemented by repeated polymerase chain reaction (PCR) amplification identified the 5' and 3' breakpoints in the α-globin gene cluster. This novel 31.2 kb deletion (NG&#95;000006.1: g.8800&#95;40007del31208) leads to the removal of the HBZ, HBA2 and HBA1 genes.

We describe a case of Hb H disease associated with homozygosity for a two nucleotide deletion in the polyadenylation signal of the α2-globin gene (HBA2: c.*93&#95;*94delAA). The patient, a 27-year-old son of a consanguineous couple, needs regular blood transfusions every 6 months.

Hb H (β4) disease is caused by deletion or inactivation of three out of four α-globin genes. A high incidence of Hb H disease has been reported all over the world. There is a wide spectrum of phenotypic presentations, from clinically asymptomatic to having significant hepatosplenomegaly and requiring occasional or even regular blood transfusions, even more severe anemia, Hb Bart's (γ4) hydrops fetalis syndrome that can cause death in the affected fetuses late in gestation. We here present a case who was diagnosed with Hb H disease that represents a new genotype for this hereditary disorder. Hb Dartmouth is a variant caused by a missense mutation at codon 66 of the α2-globin gene (HBA2: c.200T>C), resulting in the substitution of leucine by proline. We here emphasize the importance of this point mutation involving Hb H disease and also the necessity for prenatal diagnosis (PND) for those who carry this point mutation in the heterozygous state.

Although not regularly transfused, patients with non-transfusion-dependent thalassemia (NTDT) are prone to iron overload and its complications. Their molecular, phenotypical and laboratory characteristics vary in different populations and there is a need to document local prevailing patterns. We have reviewed the records of our patients with NTDT in Kuwait and documented their clinical and molecular characteristics in addition to iron status [serum ferritin and liver magnetic resonance imaging (MRI) T2*], management and complications. There were 41 patients, made up of 20 with β-thalassemia intermedia (β-TI), 18 with Hb H (β4) disease and three with Hb E (HBB: c.79G > A)-β-thalassemia (Hb E-β-thal); their ages ranged from 3 to 36 years (mean 12.5 ± 7.7). While 18 (43.9%) had been transfused at least once, only three (7.3%) had been transfused on multiple occasions. Three patients had serum ferritin >500 ng/mL; while four of 38 had mild or moderate liver iron overload. Seven (35.0%) of the β-TI patients were managed with hydroxyurea (HU) with good response. Other complications included five patients with gallstones and one each of hypothyroidism and moyamoya. The most common mutations among the β-TI patients were IVS-II-1 (G > A) and IVS-I-6 (T > C), while among the Hb H patients, the Saudi α2-globin gene polyadenylation (polyA) (AATAAA > AATAAG) mutation was responsible for all cases either as homozygotes (61.1%) or compound heterozygotes with the α-thal-2 (-α(3.7)) allele (33.3%). Although the pattern of NTDT in Kuwaiti patients is generally mild, there is a need to follow them to adulthood as the complications are cumulative and more prevalent in this group.

AEBart's disease is a thalassemia intermedia usually characterized by the interaction of α(0)-thalassemia with either deletional or non-deletional α(+)-thalassemia in Hb E heterozygote. Genotypic and phenotypic features are heterogeneous. We studied the hematologic and molecular characteristics of this disease in a cohort of 173 Thai patients encountered at our center in northeast Thailand. Hemoglobin and DNA analyses identified patients with deletional AEBart's disease (n=84), Hb Constant Spring AEBart's disease (n=81), Hb Paksé-AEBart's disease (n=5), AEBart's disease with codon 30 mutation (n=1) and two hitherto un-described forms of AEBart's disease due to interaction of Hb E heterozygote and α(0)-thalassemia with the -α(16.6)kb deletional α(+)-thalassemia (n=1) and Hb Q-Thailand (n=1). Different phenotypic expression of these AEBart's diseases with low Hb, Hct and MCV and increased RDW values with marked reduction in Hb E levels were observed. It was found that all these forms of AEBart's disease showed similar thalassemia intermedia phenotypes but those with non-deletional forms were relatively more anemic. Our data confirm that in such area with high prevalence of hemoglobinopathies such as Southeast Asia, identification of rare thalassemia alleles in a thalassemia intermedia patient should not be ignored. Careful consideration of different phenotypic expression may help in providing presumptive diagnosis of this disease where access to molecular testing is limited. However, molecular diagnostic is useful for predicting the clinical outcome and improving genetic counseling of these complex hemoglobinopathies., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Screening for α(0)-thalassemia is usually associated with a high false-positive rate, leading to an unnecessary PCR workload for accurate diagnosis. We have developed a modified Hb H inclusion test for use as a secondary screening. This test was performed on young red blood cell enriched fractions using dextran sedimentation. The study was performed in 100 subjects positive on initial screening. Confirmatory tests included Hb analysis and a multiplex PCR assay to identify α(0)-thalassemia deletions. A modified Hb H inclusion test was positive in 31 cases, 30 of whom were α(0)-thalassemia carriers (97%). The remaining case (3.0%) was homozygous for α(+)-thalassemia. The remaining 69 cases with a negative Hb H inclusion test included normal subjects, α(+)-thalassemia carriers and β-thalassemia carriers. Two of them (2/69, 3.0%) were found to be double heterozygotes for β(0)-thalassemia and α(0)-thalassemia. The overall sensitivity and specificity of the modified Hb H inclusion test for screening of α(0)-thalassemia were 94.0 and 99.0%, respectively. Therefore, we recommend the use of this test in combination with Hb analysis to exclude cases with αβ-thalassemia. This should lead to a significant reduction in the number of cases referred for PCR analysis of α(0)-thalassemia by about 50.0%., (© 2013 S. Karger AG, Basel.)

Hb H (β4) disease is an inherited hemoglobin (Hb) defect in which three of the four α-globin genes are deleted or dysfunctional. The clinical manifestations vary widely from mild asymptomatic anemia to a severely anemic state. Recent literature suggests that Hb H disease is not as benign a disorder as previously thought. Newborn screening for Hb H disease is especially appealing because the screening test is based on the detection of Hb Bart's (γ4) that is only possible within the newborn period. In a 2-year period of newborn screening, 18 babies were found to have Hb H disease in a total of 9490 newborns. The overall prevalence for Hb H disease among all newborns in southern China is approximately 1 in 500. The correct diagnosis would allow affected infants to be properly cared for and reduce mortality rate.

Abstract We report the genetic data of 435 patients with Hb H (β4) disease who presented at our center between 2005 and 2012. Our results showed that all patients had the Southeast Asian deletion (- -(SEA)) on one allele. The -α(3.7) (rightward) deletion was the most common on the other allele, followed by the -α(4.2) (leftward) deletion, Hb Constant Spring (Hb CS, α142, Term → Gln; HBA2: c.427T  > C) and Hb Quong Sze [Hb QS, α125(H8)Leu → Pro; HBA2: c.377T  > C] mutations. Two rare point mutations, α31(B12)Arg → Lys; HBA2: c.95G > A and Hb Zurich Albisrieden [α59(E8)Gly → Arg; HBA1: c.178G  > C], were also identified. Four patients had a concomitant β-thalassemia (β-thal) heterozygosity. Our results reflect the genetic heterogeneity of Hb H disease and the interaction between Hb H disease and β-thal trait in Southern China.

Objectives: To investigate the utility of isoelectric focusing electrophoresis (IEF) for identifying patients with α-thalassemia, which results from the deletion of 1 or more of the α-globin genes., Methods: Samples were selected based on their hemoglobin H (HbH) concentration observed using IEF. The samples were analyzed for the most common α-globin gene deletions using molecular analysis., Results: α-Globin gene deletions corresponding to α-thalassemia trait or silent carrier were observed in all samples with the HbH less than 2% phenotype. The genotypes of the specimens with HbH greater than 5% were consistent with HbH disease, while the wild-type phenotype control samples showed a wild-type genotype., Conclusions: Low concentrations of HbH can be detected in a patient with 1 or 2 α-gene deletions using IEF.

Genetic recombination has been implicated as a mechanism that drives mutagenesis in the human globin gene clusters, either as a result of unequal crossover or gene conversion. In this paper, a novel fusion gene was identified in a Chinese girl with hemoglobin H disease. The proband's father was a compound heterozygote for the common -α(4.2) deletion and this fusion gene, and her mother was heterozygous for the common --(SEA) deletion (--(SEA)/αα). Both her parents had a hypochromic and microcytic red cell phenotype and a normal hemoglobin level. Molecular studies revealed a compound heterozygote for the --(SEA) deletion and this novel fusion gene and the patient had the clinical features of classic hemoglobin H disease. Sequence analysis revealed that the mutant gene was the result of a fusion between the α2 and ψα1 genes. The recombination began at exon 3 of α2 gene, crossing with exon 3 of the ψα1 gene. With this recombination, the conservative 3'UTR of the α2 gene was changed, and an extensive transcript with a new signal 1048bp 3' to the terminating codon was found. The abnormal transcripts of the fusion gene read through the intergenic sequence., (Copyright © 2013 Elsevier Inc. All rights reserved.)

We describe five Chinese individuals carrying a codon 30 (-GAG) (α2) (HBA2: c.91&#95;93del) mutation, including three heterozygotes and two patients with Hb H (β4) disease. The heterozygotes presented hematological parameters of microcytosis and hypochromia. The Hb H disease patients were transfusion-independent and had survived to adulthood. Screening for this nondeletional allele, and correlation of genotype with phenotype in Hb H disease is important for genetic counseling.

A capillary electrophoresis (CE) method has been proven to be superior to a high performance liquid chromatography (HPLC) method in the detection of Hb H-Constant Spring/Paksé [Hb H (β4) Hb CS or α142, Term→Gln, TAA>CAA (α2)]/Paksé [α142, Term→Tyr, TAA>TAT (α2)]. It also has the ability to quantify Hb Bart's (γ4). The aim of this study is to analyze the efficacy of the CE and HPLC in the detection of Hb H (β4)-CS/Paksé-E [β26(B8)Glu→Lys, GAG>AAG] disease. The laboratory results from July 2009 to July 2012 were reviewed at the Thalassemia Laboratory of the Associated Medical Sciences Clinical Service Center, Chiang-Mai University, Chiang-Mai, Thailand. The HPLC or CE method was used for the diagnosis of β-thalassemia (β-thal) and hemoglobinopathies, and molecular analysis was used for the diagnosis of α-thalassemia-1 (α-thal-1) Southeast Asian (SEA) and Thai type deletions, Hb CS and Hb Paksé. Hb H-CS-E was found in six samples and Hb H-Paksé-E was found in one sample, respectively. On the capillary electrophoregram, peaks of Hb Bart's and Hb CS/Paksé were observed in all samples with the mean levels at 2.4 and 1.0%, respectively. These peaks were also presented on the HPLC chromatogram. However, the Hb CS/Paksé level could be quantified in only three of these seven (43.0%) samples. Therefore, CE was proven to be superior to HPLC in the detection of Hb H-CS/Paksé-E disease, which will assist in diagnostic, counseling and prevention programs for these diseases.

We used quantitative real-time polymerase chain reaction (qPCR) and high resolution melting (HRM) analyses for the detection of the common α-thalassemia (α-thal) genotypes in 40 northern Thai Hb H (β4) patients. The α(0)-thal [- -(SEA) (Southeast Asian) deletion] was detected by a multiplex gap real-time PCR. To determine the α(+)-thal, three primer pairs were designed. The A-primer pair was used to amplify the 3' terminal DNA sequences of the HBA2 gene, and the B-primer pair amplified the 5' flanking region of the HBA1 gene. The C-primer pair amplified the 3' terminal DNA sequences of the HBA1 gene and was used as an internal control. The -α(4.2) (leftward) and -α(3.7) (rightward) deletions were determined by monitoring the absence of PCR product(s). The Hb H patients who had a negative PCR result for the A-primer pair but positive for the B- and C-primer pairs carried the -α(4.2) deletion, while the -α(3.7) deletion carriers were negative for the A- and B-primer pairs. In the case of Hb H with Hb Constant Spring (Hb CS, α142, Term→Gln; HBA2: c.427T>C), all primer pairs were positive, HRM analysis of the PCR product of the A-primer pair was introduced to analyze the Hb CS gene. It can distinguish clearly between normal and Hb CS genotypes. The applied methods for the determination of the α(0)- and α(+)-thal genotypes revealed the results to be as accurate as conventional gap-PCR and the direct DNA sequencing methods but resulted in a much simpler and faster procedure.

Objective: To study the characteristics of genotype spectrum and hematologic parameters in children with HbH disease in the North Guangxi region., Methods: HbH disease was identified by clinical manifestations, routine blood tests and hemoglobin electrophoresis in 166 children who came form the North Guangxi region. Genotypes were determined by Multi-PCR combined with PCR reverse dot blot. DNA sequencing was used when the genotype could not be identified by regular methods., Results: Of the 166 children with HbH disease, 8 genotypes were identified: --SEA/-α3.7 (82 cases), --SEA/-α4.2 (40 cases), --SEA/αCSα (38 cases), --SEA/αQSα (1 case), --SEA/αWSα (1 case), --SEA/αCD43/44 (-C) α (1 case), --SEA/-α3.7 plus CD17 (A→T) (1 case) and --SEA/-α4.2 plus CD41-42(-TTCT) (1 case). One case was confirmed as the heterozygote of --SEA and an unknown mutation. In the 134 cases with complete medical data, 2 had normal hemoglobin levels, 36 manifested mild anemia, 90 manifested moderate anemia, and 6 (genotype: --SEA/αCSα) showed severe anemia because of the coexistence of infection. Children with the genotype of --SEA/-α3.7 (69 cases), --SEA/-α4.2 (31 cases) and --SEA/αCSα (34 cases) had hemoglobin levels of 62-120, 69-127 and 34-110 g/L respectively. The hemoglobin level in the --SEA/αCSα group was significantly lower than in the deletional HbH disease group (genotypes: --SEA/-α3.7 and --SEA/-α4.2 ) (P<0.05). In contrast, MCV levels in the --SEA/αCSα group were significantly higher than in the deletional HbH disease group (P<0.05)., Conclusions: The genotype spectrum of HbH disease is diverse in the North Guangxi region. Deletional genotype is prevalent. The disease is heterogeneous. The children with --SEA/αCSα HbH disease have severer anemia and higher MCV levels than those with deletional HbH disease.