Coinheritance of High Oxygen Affinity Hb Helsinki [HBB: c.248A>T; β82(EF6)Lys→Met] with Hb H Disease

Hb Helsinki [HBB: c.248A>T; β82(EF6)Lys→Met] is a high oxygen affinity hemoglobin (Hb) causing polycythemia, whereas Hb H (β4) disease causes mild to severe chronic hemolytic anemia. The clinical characteristics, gel electrophoresis, capillary electrophoresis (CE) and molecular genotyping of a case of Hb Helsinki coinherited with Hb H disease in an ethnic Malay is described, illustrating the interaction between the β-globin variant and coinheritance of three α gene deletions. The proband was asymptomatic, exhibited microcytosis and a normal with Hb value.     

Hb Ullevaal [β78(EF2)Leu→Val; HBB: c.235C>G], a New Hemoglobin Variant Interfering with Hb A1c Measurement Using a Cation Exchange High Performance Liquid Chromatography Method

A new hemoglobin (Hb) variant was detected during Hb A_1c measurement. DNA sequencing showed heterozygosity for the single nucleotide substitution (C?>?G) on the β-globin gene causing an amino acid change [β78(EF2)Leu→Val; HBB: c.235C?>?G]. The new Hb variant was designated Hb Ullevaal after the hospital at which it was discovered. Heterozygosity for Hb Ullevaal appears to have no clinical significance. However, it interferes with Hb A_1c measurement by cation exchange high performance liquid chromatography (HPLC), causing falsely low Hb A_1c concentration when using the Tosoh G7 apparatus in variant mode.     

A Mosaic Expression of a Hb J-Amiens (HBB: c.54G > T; p.Lys18Asn) and its Interference with Hb A1c Analysis

Abstract

We report the case of a 56-year-old Caucasian woman in whom hemoglobinopathy screening was triggered following an aberrant Hb A_1c analysis. Preliminary diagnosis of the hemoglobin (Hb) variant was obtained through cation exchange high performance liquid chromatography (HPLC) and gel electrophoresis. DNA analysis confirmed the presence of Hb J-Amiens [β17(A14)Lys→Asn; HBB: c.[54G?>?C or 54G?>?T)]. However, an unbalanced ratio between wild type and mutant signal after direct sequencing and a lower than expected percentage of this Hb variant led to the suggestion of a mosaic expression. Furthermore, different methods [capillary zone electrophoresis (CZE), cation exchange HPLC and boronate affinity] were tested to study the possible interference of this variant with Hb A_1c measurements. These investigations showed a clinically relevant difference between the methods tested. Hb A_1c analysis may lead to the discovery of new Hb variants or mosaicism for previously described Hb variants. This may have genetic consequences for the offspring of carriers and brings about the question of partner testing.     

Complex Interaction of Hb Q-Thailand (HBA1: c.223G>C) with β-Thalassemia/Hb E (HBB: c.79G>A) Disease

Hb Q-Thailand [α74(EF3)Asp→His (α1), GAC>CAC, HBA1: c.223G>C] is an abnormal hemoglobin (Hb) frequently found in Thailand and Southeast Asian countries. The association of the α^Q-Thailand allele with other globin gene disorders has important implications in diagnosis. Here, we report how to diagnose the coinheritance of Hb Q-Thailand with β-thalassemia (β-thal)/Hb E disease in four Thai samples from high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) testing results. Understanding of the HPLC chromatogram and CE electropherogram patterns of this complex mutation is important for interpretation of testing results and providing genetic counseling.     

A New β-Chain Variant: Hb Stockholm [β 7(A4)Glu→Asp] Causes Falsely Low Hb A1c

A new β?hemoglobin (Hb) variant, Hb Stockholm [β7(A4)Glu→Asp], is described. The variant was characterized by mass spectrometry and DNA sequencing. The new variant is clinically silent but interferes with Hb A_1c quantification using ion exchange chromatography, causing a falsely low Hb A_1c level when using the Bio-Rad VARIANT II? System.     

New Insights on β-Thalassemia in the Palestinian Population of Gaza: High Frequency and Milder Phenotype Among Homozygous IVS-I-1 (HBB: c.92+1G>A) Patients with High Levels of Hb F

β-Thalassemia (β-thal) is a very common disease in the Palestinian population of the Gaza Strip. We studied their mutation frequency and clinical features. Thirteen different mutations were identified. The most common mutation was IVS-I-1 (G>A) (HBB: c.92+1G>A), which was prevalent in 31.5% of the thalassemia alleles studied. The IVS-I-110 (G>A) (HBB: c.93?21G>A) mutation was found in 25.0% of the alleles. Homozygotes for the IVS-I-1 mutation had higher mean hemoglobin (Hb) levels, required less blood transfusions, and lower transferrin saturation than the homozygotes for the IVS-I-110 mutation. This milder phenotype was, most likely, the result of the persistent production of Hb F; it was 9-fold higher in absolute terms (g/dL) and 7.7-fold higher in relative terms (percentage of total Hb). About half of our IVS-I-1 patients carried the XmnI polymorphism, which is known to be associated with elevated Hb F levels.     

Haemoglobin (Hb) G-Philadelphia, Hb Stanleyville-II, Hb G-Norfolk, Hb Matsue-Oki and Hb Mizushi can form a panel of α-chain variants that overlap in their phenotype: the novel use of StyI to screen for Hb G-Philadelphia

Introduction: Haemoglobin (Hb) G‐Philadelphia mutation is a common alpha‐globin chain variant [α68(E17)Asn > Lys]. Combined high performance liquid chromatography (HPLC) and isoelectric focusing (IEF) can be used in a presumptive diagnosis of Hb G‐Philadelphia, but there are other α‐chain variants with a similar phenotype that cannot be excluded. Our aim was to develop a novel StyI restriction enzyme assay to diagnose the common Hb G‐Philadelphia mutation and to identify any other variants with a similar phenotype by DNA sequencing. Methods: Thirty‐one cases given a presumptive diagnosis as Hb G‐Philadelphia by HPLC and IEF were subjected to DNA analysis by restriction enzyme digestion using StyI. Negative cases were then subjected to DNA sequencing. Results: Twenty‐two cases (78.6%) of 28 cases amplified were tested positive for Hb G‐Philadelphia by StyI restriction digestion. Sequencing of the six negative cases revealed two cases of Hb G‐Philadelphia with C→A mutation in codon 68 in α2 globin gene, plus one case each of Hb G‐Norfolk Hb Stanleyville‐II, Hb Matsue‐Oki and Hb Mizushi. Conclusion: A novel StyI restriction enzyme can be used to confirm the commonest type of Hb G‐Philadelphia. DNA sequencing identified four other α‐chain variants with a similar HPLC and IEF phenotype.     

Hb Dartmouth (HBA2: c.200T>C): An α2-Globin Gene Associated with Hb H Disease in One Homozygous Patient

Abstract

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.     

Homozygosity for HBA1: c.179G > A: Hb Adana in an Infant

Hb Adana (HBA1: c.179G?>?A) is a very rare, unstable form of α-globin variant that results from deficient synthesis of functional α chains. We present a 2-month-old boy with hypochromic microcytic anemia, and remarkable anisocytosis, target cells and basophilic stippling on his peripheral blood smear. α-Globin gene analysis of the patient determined homozygosity for HBA1: c.179G?>?A, a mutation known as Hb Adana. On his follow-up visit, hemoglobin (Hb) levels were stable at 9.0–9.5?g/dL and mean corpuscular volume (MCV) was 62.2–62.5?fL without the need for a blood transfusion. Clinical and hematological findings of our case were comparable to Hb H (β4) or β-thalassemia intermedia (β-TI)-like phenotypes, despite the fact that he carried an α1 gene mutation. Heterozygosity for the HBA1: c.179G?>?A mutation may also lead to microcytosis only as seen in his parents. According to our current knowledge, this is the first described case with homozygosity for the Hb Adana mutation, carried on the α1 gene. The relatively mild presentation of the case highlights the milder phenotypic consequences of nondeletional α mutations in the α1 vs. the α2 gene.     

Hb A2-Tianhe (HBD: c.323G>A): First Report in a Chinese Family with Normal Hb A2-β-Thalassemia Trait

Coinheritance of δ-globin variants along with β-globin gene defects can interfere with correct diagnosis of β-thalassemia (β-thal) trait. In this report, we present the coinheritance of a δ-globin variant, Hb A₂-Tianhe [δ107(G9)Gly→Asp; HBD: c.323G>A] and a heterozygous β-thal in a Chinese individual with microcytosis, hypochromia and a normal Hb A₂ level.     

Hb A1c Determination by Capillary Electrophoresis is an Efficient Method for Detecting β-Thalassemias and Hemoglobin Variants

Glycated hemoglobin (Hb A_1c) determination by multicapillary zone electrophoresis (MZE) can additionally be used to detect Hb A₂, Hb F and most common hemoglobin (Hb) variants. We assessed the effectiveness of this method for detecting β-thalassemia (β-thal), δβ-thalassemia (δβ-thal) and most common Hb variants. Moreover, Hb F/Hb A₂ is evaluated as an index for discriminating between β- and δβ-thal traits. The theoretical β-thalassemia major (β-TM) birth rate in our healthcare area is calculated and contrasted with real data. A MZE technique was used for Hb A_1c measurements in 27,724 patients. Previous criteria for carrier detection were established and subsequently confirmed by molecular biology techniques. Positive predictive value (PPV) was 100.0%. The prevalence of β-thal trait (including δβ-thal) was 0.34%. The most prevalent mutations (estimated per 100,000 population) were HBB: c.118C?>?T (57.7%), HBB: c.93-21G>A (50.5%), HBB: c.92?+?1G?>?A (43.3%), HBB: c.92?+?6T?>?C (32.5%) and HBB: c.20delA (18.0%) for β-thalassemias, and Hb S (HBB: c.20A?>?T) (32.5%) and Hb J-Baltimore (HBB:c.3880T>A) (28.9%) for Hb variants. We found a paradoxical result between the theoretical β-TM birth rate and real data. We calculated an optimal Hb F/Hb A₂ index cutoff of 0.71 for discriminating between β- and δβ-thal traits. This method is highly cost-effective for detecting β-thalassemias and common Hb variants. Prevalence results match previous data for the Spanish population. Heterogeneity of mutations in Spain has markedly increased as a consequence of migration. The Hb F/Hb A₂ index cutoff could be used to predict δβ-thal trait.     

Interaction between Hb E and Hb Yala (HBB:c.129delT); a novel frameshift beta globin gene mutation,resulting in Hemoglobin E/β0 thalassemia

Objectives: There are more than 200 known mutations found in patients with β-thalassemia, a possibility to identify an unknown or novel mutation becomes less possible. Here, we report a novel mutation in a patient from Thailand who presented with chronic hemolytic anemia.

Methods: A comprehensive hematology and DNA analysis was applied in the index patient and her mother.

Results: Hematological and hemoglobin analyses were consistent with the clinical diagnosis of Hb E/β⁰-thalassemia. However, we could find only Hb E heterozygous mutation using our common polymerase chain reaction-based mutation detection of the β-globin genes. Furthermore, the molecular analysis demonstrated a novel T-deletion at codon 42 of the second exon of the β-globin gene which we named ‘Hb Yala’ according to the origin of this index family.

Discussion: This mutation was assumed to generate a truncated β-globin chain terminating at codon 60 with possible unstable variant leading to a ‘null’ or β⁰-thalassemia. However, the clinical phenotype was surprisingly mild and no other ameliorating genetic factors, including co-inheritance of α-thalassemia and high propensity of Hb F by Xmn I polymorphism, were found.

Conclusion: This report has provided evidence that genotype–phenotype correlation in thalassemia syndromes is highly complex and a correct clinical severity classification of thalassemia should be mainly based on clinical evaluation.     

Molecular characterization and origins of Hb Constant Spring and Hb Paksé in Southeast Asian populations

Hemoglobin Constant Spring (Hb CS) and Hb Paksé, two abnormal Hbs characterized by elongated α-globin chains resulting from mutations of the termination codon in the α2-globin gene, are the most prevalent nondeletional α-thalassemias in Southeast Asia. To determine the origins of these two variants in the region, we have determined α-globin gene haplotypes associated with these two variants on 120 Thai, eight Cambodian, and six Laos alleles, and the results were compared with those reported previously for the Chinese and Mediterranean. Five haplotypes were found to be associated with 131 α^CS genes examined, whereas a single haplotype was linked to all the α^Paksé genes in these Southeast Asian populations. All the α^CS haplotypes differed from those of the Mediterranean, but one of them was similar to a Chinese α^CS gene reported previously. It is concluded that there are multiple origins of the α^CS and a single origin of the α^Paksé mutations in Southeast Asia. Hematological findings confirm the mild thalassemia intermedia phenotypes for pure homozygous Hb CS and homozygous Hb CS with Hb E heterozygote and Hb E homozygote. The appearance of Hb CS peak by high-performance liquid chromatography analysis indicates the ability to form a tetrameric Hb molecule between the α^CS and β^E chains, leading to a novel derivative with similar characteristics to Hb CS.     

血Hcy、Hb A_(1c)及尿U-m Alb检测诊断早期糖尿病肾病损伤的价值分析

选择2017年2月至2018年8月42例早期糖尿病肾病损伤患者为观察组,健康体检者42例为对照组。结果观察组Hcy、Hb A_(1c)、U-mAlb水平较高于对照组,(P 0. 05);观察组Hcy、Hb A_(1c)、U-mAlb异常检出率较高,(P 0. 05);Hcy、U-mAlb、Hb A_(1c)联合检测阳性率较高,(P 0. 05)。结论尿U-mAlb、血Hcy、Hb A_(1c)联合检测能提高阳性检出率。     

青岛地区大学生Hb水平检测及意义

采用血液自动分析仪对青岛地区112例大学生进行血红蛋白（Hb）、红细胞计数、红细胞压积的检测。发现男性Hb平均水平（144．15g／L）明显高于女性（125．47g／L）；按WHO标准有1例男性和6例女性诊断为贫血，贫血患病率为6．2％。认为合理膳食和良好的饮食习惯对预防缺铁性贫血十分重要。     

肝硬化患者外周血Hb变化的意义

1996年9月~2006年5月,我们对780例肝硬化患者的外周血Hb含量进行检测,以探讨肝硬化患者Hb变化的临床意义。资料与方法:本文780例肝硬化患者(观察组),男511例、女269例,年龄(54.2±11.8)岁。均符合1990年全国肝硬化学术会议制定的诊断标准,排除合并消化道出血者。其中60例病情恶     

Hb Johnstown [β109(G11)Val→Leu]: a High Oxygen Affinity Variant Associated with β0‐Thalassemia

Hb Johnstown [β109(G11)Val→Leu], a high oxygen affinity hemoglobin (Hb) variant associated with β⁰‐thalassemia (thal) [IVS‐I‐1 (G→A)], was identified in an 8‐year‐old girl referred to our laboratory because of erythrocytosis and a left‐shifted oxygen dissociation curve (ODC). The phylogenetic tree showed that the mother was heterozygous for the Hb variant and the father was a β⁰‐thal carrier. This Hb variant, with normal electrophoresis, was characterized at the DNA level by β gene sequencing. The amino acid substitution potentially disrupts α1β1 contacts in the deoxyHb conformation, thus shifting the equilibrium towards the high affinity oxyHb conformation. The erythrocytosis and low values for actual P₅₀ due to Hb Johnstown were more marked due to the co‐inheritance of the β⁰‐thal.     

High Incidence of Hb D-Los Angeles [β121(GH4)Glu→Gln] in Denizli Province,Aegean Region of Turkey

Denizli Province is located in the inner part of the Aegean region of Turkey and is one of the target areas for premarital screening. Here we report the abnormal hemoglobins (Hbs) observed during a premarital screening program in our region. According to our results, Hb D-Los Angeles [β121(GH4)Glu→Gln (GAA→CAA] (also known as D-Punjab, D-North Carolina, D-Portugal, Oak Ridge and D-Chicago), is the most frequent abnormal Hb in this region.