Characterization of Homozygous Hb Setif (HBA2: c.283G>T) in the Iranian Population

Hemoglobin (Hb) variants are abnormalities resulting from point mutations in either of the two α-globin genes (HBA2 or HBA1) or the β-globin gene (HBB). Various reports of Hb variants have been described in Iran and other countries around the world. Hb Setif (or HBA2: c.283G>T) is one of these variants with a mutation at codon 94 of of the α2-globin gene that is characterized in clinically normal heterozygous individuals. We here report clinical and hematological findings in two homozygous cases of Iranian origin for this unstable Hb variant.     

Hb Memphis [HBA2: c.70G>C (or HBA1)] in a Turkish Child: A Case Report and Comparison to Hb Q-Thailand (HBA1: c.223G>C)

Hb Memphis [α23(B4)Glu→Gln; HBA2: c.70G?>?C (or HBA1)] is a stable hemoglobin (Hb) variant caused by a substitution of glutamine for glutamic acid at residue 23 of the α2- or α1-globin chain. Heterozygous Hb Memphis has no known clinical or hematological effect, and all prior reports have resulted from observations in persons of African descent with sickle cell disease and an unusually mild clinical course. Family studies suggest that Hb Memphis may modulate sickling. Only brief characterizations of Hb Memphis trait in the absence of Hb S are present in the current literature. We report isolated Hb Memphis trait in Turkish individuals in whom the initial laboratory incorrectly identified the α variant as Q-Thailand [α74(EF3)Asp→His; HBA1: c.223G?>?C]. In one case, a heterozygous ?3.7?kb α gene deletion was also present, which increased the variant Hb level to a percentage similar to that of the more common Hb Q-Thailand, which may have led to the misidentification. Herein, we discuss the characterization and comparison of these variants and underscore the necessity of confirming characterization by more than one method prior to assigning Hb variant identification.     

Quantitative Trait Loci Influencing Hb F Levels in Southern Thai Hb E (HBB: c.79G>A) Heterozygotes

Variation of fetal hemoglobin (Hb F) expression in heterozygous Hb E (HBB: c.79G>A) individuals is associated with several genetic modifiers and not well understood. This study was undertaken in order to determine the effect of single nucleotide polymorphisms (SNPs), including XmnI ^Gγ (rs7482144), rs766432 on the BCL11A gene and rs9376074 on the HBS1L gene, on Hb F levels in Southern Thai heterozygous Hb E individuals. A total of 97 Southern Thai subjects carrying heterozygous Hb E were selected for the hematological study. After excluding the samples with α-thalassemia (α-thal) interaction or moderate anemia, because both conditions can affect the hematological parameters, the remaining 74 samples were submitted to SNP analysis. Hematological parameters were measured using an automated hematology analyzer and high performance liquid chromatography (HPLC). The results show that rs766432 was strongly associated with increased Hb F levels and rs7482144 was associated with Hb F levels in each subgroup (genotype) of rs766432. This study suggested that the BCL11A locus has a major effect on Hb F levels compared with the XmnI polymorphism in Hb E heterozygotes. This association of Hb F levels with SNPs is useful for the interpretation of hemoglobin (Hb) typing in heterozygous Hb E samples with high Hb F levels. Future research will need to address the better understanding of the mechanisms of the SNPs that regulate Hb F production without stress erythropoiesis in Hb E heterozygotes.     

Hb Presbyterian (HBB: c.327C>G) in a Nicaraguan Family

Hemoglobin (Hb) is the protein responsible for oxygen transportation. It is a tetrameric protein comprising two α- and two β-globin subunits. In the literature, a large number of mutations in the α- and β-globin genes have been documented. Among these mutations, Hb Presbyterian (HBB: c.327?C>G), is a naturally occurring mutant exerting low oxygen affinity. The C to G exchange (AAC>AAG) at codon 108 of the β-globin gene results in the substitution of asparagine by lysine. Here, we document the identification of HBB: c.327?C>G in a 6-year-old female patient and her father from Nicaragua and Cuba, respectively. The presence of the abnormal Hb was confirmed by cellulose acetate electrophoresis, high performance liquid chromatography (HPLC) and genomic DNA sequencing. The β-globin gene sequences for both, father and daughter, disclosed the heterozygous mutation at codon 108 to be Hb Presbyterian or HBB: c.327?C>G. The mutant Hb was previously reported in four families from North America, Germany, Japan and Spain, respectively. This is the fifth family carrying HBB: c.327?C>G described to date and the first report from Latin America.     

Severe Drug-Induced Hemolysis in a Patient with Compound Heterozygosity for Hb Peterborough (HBB: c.334G>T) and Hb Lepore-Boston-Washington (NG_000007.3: g.63632_71046del)

Unstable hemoglobins (Hbs) are often overlooked in the differential diagnoses of drug-induced hemolysis. Hb Peterborough [β111(G13)Val→Phe; HBB: c.334G>T] is a rare unstable Hb variant, predominantly found in individuals of Italian descent, due to a structural defect involving a single amino acid substitution (phenylalanine for valine at position 111 of the β-globin chain). Unstable Hb variants are often inherited in the heterozygous state with Hb A (α2β2) and rarely in compound heterozygosity with other Hb variants. The presence of another variant Hb often alters the phenotype, occasionally resulting in more severe disease. Using a combination of molecular techniques; multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing, we identified a compound heterozygosity for Hb Peterborough and Hb Lepore-Boston-Washington (Hb LBW) [δ87, β116; NG_000007.3: g.63632_71046del] in a middle-aged gentleman with a history of chronic microcytic anemia and splenomegaly, presenting with severe drug-induced hemolysis, which was managed conservatively. The clinical history and presentation reflect the dual pathology due to the presence of two variant Hbs and their associated phenotypes. In this article, we discuss the phenotype resulting from the interaction of Hb Peterborough and Hb LBW and emphasize the importance of molecular testing in the diagnosis of rare Hb variants.     

A Coincidental Discovery of a New Stable Variant (Hb Hachioji or HBB: c.187C>T) in a Patient with Chronic Hemolytic Anemia of Unexplained Origin

We report a new hemoglobin (Hb) variant, Hb Hachioji (HBB: c.187C>T), which was detected in a 32-year-old male with hemolytic anemia. The proband had undergone splenectomy in his childhood after being diagnosed with hereditary spherocytosis (HS) with no clinical improvement. A recent study showed that Heinz bodies were frequently observed in his red cells, however, no abnormal band was separated by isoelectric focusing (IEF), and the isopropanol (instability) test was negative. Direct sequencing revealed that the proband was a heterozygous carrier of a novel mutation (GCT>GTT) at codon 62 of the β-globin gene, leading to an alanine to valine substitution. This variant was named Hb Hachioji. Characterization at the mRNA level by cDNA sequencing detected β^Hachioji mRNA, as well as β^A mRNA. Subsequently, study of the proband’s family indicated that his father was a carrier of this Hb variant, although unexpectedly, the father was asymptomatic and clinically healthy. Oxygen affinity measurement of total Hb showed no alteration in the P₅₀ and oxygen equilibrium curve. The presence of Hb Hachioji was confirmed by mass spectrometry (MS). Hb Hachioji comprised approximately 50.0% of the total Hb and was a stable variant. The phenotypic discrepancy between these two carriers suggests that Hb Hachioji may not be associated with the hemolytic involvement in the proband. P4.2Nippon, which is the primary cause of most cases of Japanese HS, was absent in the proband’s parents. The coexistence of glucose-6-phosphate dehydrogenase (G6PD) deficiency was ruled out. Thus, the cause of hemolytic involvement in this patient remains unclear.     

Rare Hemoglobin Variants: Hb G-Szuhu (HBB: c.243C>G), Hb G-Coushatta (HBB: c.68A>C) and Hb Mizuho (HBB: c.206T>C) in Sri Lankan Families

Abstract

In this short communication, we describe the clinical presentation of unusual hemoglobin (Hb), variants in three Sri Lankan cases under study for β-thalassemia intermedia (β-TI). We believe this is the first report on their occurrence in Sri Lanka as well as from the Indian subcontinent. During a molecular study performed on β-TI patients, we identified three unusual Hb variants as Hb G-Szuhu (HBB: c.243C>G), Hb G-Coushatta (HBB: c.68A>C) and Hb Mizuho (HBB: c.206T>C) in three unrelated families. Hb G-Szuhu and Hb G-Coushatta were found in combination with the common β-thalassemia (β-thal) mutation, IVS-I-5 (G>C). Both probands had mild anemia with greatly reduced red cell indices and had non palpable livers and spleens, however, by ultrasound, both were observed to be enlarged. The final Hb variant, Hb Mizuho, was identified as a heterozygous mutation found in both proband and his mother. Both family members had severe anemia and were regularly transfused and had increased red cell parameters.     

HBB: c.316-125A>G and HBB: c.316-42delC: Phenotypic Evaluations of Two Rare Changes in the Second Intron of the HBB Gene

We report two very rare changes in the second intron of the HBB gene, a substitution at nucleotide (nt) 726 [IVS-II-726 (A>G) (β⁺), NM_000518, HBB: c.316-125A>G] and a deletion of a cytosine at nt 809 [IVS-II-809 (–C) (β), NM_000518, HBB: c.316-42delC] identified during the screening program for hemoglobinopathies in the resident Sicilian population. The purpose of this study was to evaluate the clinical implication of these rare changes, particularly in coinheritance with known mutations in the globin clusters, in order to conduct an appropriate genetic counseling for at-risk couples. Molecular analysis detected the first rare nt substitution in two cases in simple heterozygosity and in two cases in association with other known mutations on globin genes, while the deletion was identified in a pregnant woman, carrier of β-thal, and in her fetus at prenatal diagnosis (PND) for hemoglobinopathies. The present study emphasizes the importance of sharing the observed changes in the globin gene cluster, especially in the case of new or rare undefined mutations, in order to facilitate the determination of their phenotypic expression and possible interactions with known molecular defects.     

Rare Association of Hb D-Los Angeles (HBB: c.364G>C) with Hb H Disease: Diagnosis and Clinical Implications

Abstract

Hb D-Los Angeles (or Hb D-Punjab) (HBB: c.364G?>?C) is found worldwide and is derived from a point mutation in the β-globin gene prevalent in the Punjab region of Northwestern India. Heterozygous or homozygous inheritance does not cause significant medical problems, whereas association with other hemoglobinopathies, especially β-thalassemia (β-thal) and sickle cell disease, changes the phenotype. Coinheritance of Hb D-Los Angeles with Hb H disease (α–/–?–) has never been reported before. The presence of this rare combination in a family of Greek origin is herein described, and the challenges involving clinical management are discussed.     

Compound Heterozygosity for Hb Alperton (HBB: c.407C>T) and IVS-I-5 (G>C) (HBB: c.92+5G>C) Mutations Presenting as a Moderate Anemia in an Indian Family

While knowledge of HBB gene mutations is necessary for offering prenatal diagnosis (PND) of β-thalassemia (β-thal), a genotype-phenotype correlation may not always be available for rare variants. We present for the first time, genotype-phenotype correlation for a compound heterozygous status with IVS-I-5 (G>C) (HBB: c.92+5G>C) and HBB: c.407C>T (Hb Alperton) mutations on the HBB gene in an Indian family. Hb Alperton is a very rare hemoglobin (Hb) variant with scant published information about its clinical presentation, especially when accompanied with another HBB gene mutation. Here we provide biochemical as well as clinical details of this variant.     

Co‐inheritance of Hb Hershey [β70(E14) Ala→Gly] and Hb La Pommeraie [β133(H11)Val→Met] in a Sicilian subject

Objectives: This report represents the first observation in Sicily of two rare β‐globin gene variants, Hb Hershey [β70(E14) Ala→Gly] and Hb La Pommeraie [β133(H11)Val→Met], found in a 35‐year‐old male patient from Messina, in the north‐east of Sicily during population screening for hemoglobinopathies. Methods: The occurrence of the Hb variants was assessed by cation exchange chromatography while complete blood counts were obtained using automatic cell counters. Red cell lysates were analyzed by electrophoresis at alkaline and acid pH. Stability of hemoglobin was checked by the isopropanol precipitation test and by the heat tests while inclusion bodies and reticulocyte count were determined by incubation of blood samples with brilliant cresyl blue. Molecular analysis was performed by DNA sequencing of β‐ and α‐globin genes. Results: We observed an abnormally high performance liquid chromatography elution with a slight reduction in mean corpuscular volume and mean corpuscular haemoglobin parameters and mutations at codon 70 G C C→G G C (Hb Hershey) and at codon 133 G TG→ A TG (Hb La Pommeraie) in β‐globin gene. Conclusion: Family analysis of three generations demonstrated the presence of these two mutations in trans. So it was possible to describe the phenotypes of these variants in a heterozygous state and in double heterozygous state.     

A new unstable variant of the fetal hemoglobin HBG2 gene: Hb F‐Turritana [Gγ64(E8)Gly→Asp,HBG2:c.194G>A] found in cis to the Hb F‐Sardinia gene [Aγ(E19)Ile→Thr,HBG1:c.227T>C]

A new variant of the fetal hemoglobin (Hb) was observed in a newborn baby subjected to phototherapy due to jaundice, by means of electrophoretic and chromatographic techniques. The variant Hb resulted unstable by the isopropanol stability test. After HBG2 gene sequencing, the G to A transversion at codon 64, position eight of the E helix, was found, which corresponds to the Asp for Gly amino acid substitution. The new variant was called Hb F‐Turritana [^Gγ64(E8)Gly→Asp, HBG2:c.194G>A]. Incoming aspartic acid residue, bulky and negatively charged, may be responsible for alteration of the heme pocket steric configuration and for instability. The new abnormal HBG2 gene was found to be associated in cis with the mutated HBG1 gene, which characterizes the Hb F‐Sardinia [^Aγ (E19)Ile→Thr, HBG1:c.227T>C] variant.     

Hb Grand Junction (HBB: c.348_349delinsG; p.His117IlefsX42): A New Hyperunstable Hemoglobin Variant

Hyperunstable hemoglobinopathy (HUH) [dominantly inherited β-thalassemia (β-thal)] is a relatively rare form of congenital hemolytic anemia in which mutations occur in the genes encoding for α and β chains, or both chains of the hemoglobin (Hb) molecule. We describe two Hispanic adolescents with a new unstable Hb variant (HBB: c.348_349delinsG; p.His117IlefsX42), resulting from a frameshift mutation at codons 115/116 of the β-globin gene. Both patients also have a 3.7?kb deletion on one α gene, leading to a decreased imbalance between α and β chain formation, and subsequently a milder phenotype than that seen in other hyperunstable Hb variants.     

Compound Heterozygote of Hb S (HBB: c.20A>T)/Hb Westdale (HBB: c.380_396delTGCAGGCTGCCTATCAG): Report of Four Cases from Odisha State,India

We report four cases of compound heterozygotes for Hb S (HBB: c.20A>T) and a rare β⁰-thalassemia (β⁰-thal) mutation, Hb Westdale (HBB: c.380_396delTGCAGGCTGCCTATCAG), characterized by a 17?bp deletion between codons 126 to 131 in exon 3 of the β-globin gene of human hemoglobin (Hb) confirmed by direct β-globin gene sequencing. All four cases were from four unrelated families belonging to the Agharia caste, an endogamous ethnic community of the Sundargarh and Jharsuguda districts of Odisha State, India. Detailed observations indicated that all four cases of Hb S/Hb Westdale were clinically severe. On family screening, six family members were found to be heterozygous for Hb Westdale and were asymptomatic. Deletional α-thalassemia (α-thal) and XmnI polymorphism were studied for all the Hb Westdale cases. The Hb S/Hb Westdale cases had an early median age at onset of symptoms and presentation, more requirement of blood transfusions, splenomegaly and hepatomegaly and were found to be clinically more severe when compared with the Hb S-β-thal with IVS-I-5 (G>C) (HBB: c.92?+?5G>C) cases. Overall, the findings indicate that this rare and hitherto unreported compound heterozygosity of Hb S/Hb Westdale is a clinically significant hemoglobinopathy and its finding in a large endogamous community of Odisha State, India will have important implication in the epidemiology and understanding of the clinical spectrum of sickle cell disease in Indian context and prenatal diagnosis.     

Hematological and Molecular Findings in the First Case of Hb J-Norfolk [HBA2: c.173G>A (or HBA1] in an Indian Patient

Abstract

We here report a case of a 23-year-old female from Mumbai, Maharashtra, India who was detected to carry the α chain variant Hb J-Norfolk [HBA2: c.173G>A (or HBA1]. She had no clinical symptoms and was referred to us for routine investigations and screening. An abnormal peak was detected on both high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) with a fast-moving band on cellulose acetate electrophoresis. There is no detailed study on the HPLC and CE pattern of this hemoglobin (Hb) variant, and therefore, this study will help in detecting and avoiding missing these variants during routine investigations and population screening. This is the first report of this variant in the Indian population.     

Detection of Hb A2 and Hb Constant Spring (HBA2: c.427T>C) by Capillary Electrophoresis in a Patient with Hb H-Hb CS Disease

Abstract

Hb A₂ (α2δ2) is one of the key components looked for in hemoglobinopathies screening programs. Therefore, quantitative and accurate method for Hb A₂ value determination is essential for routine screening. Here, we report a case of Hb A₂ and Hb Constant Spring (Hb CS, HBA2: c.427T>C) with Hb H-Hb CS disease that was not detected by high performance liquid chromatography (HPLC), while Hb A₂ and Hb CS were clearly quantified by capillary electrophoresis (CE).     

2017—2018年广州市H3N2流感病毒流行及血凝素基因分子特征分析

目的 对广州市H3N2流感病毒进行基因变异和进化分析,为H3N2流感科学防控提供科学依据。方法 对广州市2017年1月-2018年9月流感监测标本进行H3N2病毒检测和分离,并对HA基因进行测序,通过生物信息学软件分析病毒变异和进化特点。结果 所监测的8 535份标本中,检出H3N2流感阳性标本386份,阳性率为4.52%。对其中16株分离株HA基因测序结果显示,与同年度疫苗推荐株A/Hong Kong/4801/2014相比,2017年广州H3N2病毒A 区抗原位点变异频率较高,多发生于140位、144位和150位,其中有7株病毒发生新抗原漂移,变异毒株占比43.75%。受体结合位点变异主要发生在前壁,位于T131K位和T135K(N)位。糖基化位点变异同样多发生于A区抗原位点和受体结合位点前壁。2017年广州H3N2流感病毒均位于3C.2a分支,但分支内又进一步进化形成3个不同的小流行分支,包括3C.2a1分支,以及与2016年北京、2017年美国分离株亲缘相近的另外两个小分支。结论 2017年广州H3N2流感病毒HA蛋白重要氨基酸位点的变异表现遗传多态性,特别是在抗原性上可能发生了较大变异。在基因进化上表现为多样性和复杂性,呈现多分支进化特点。因此有必要密切监测流行毒株的进化趋势,以期及时对疫苗株的匹配性进行有效评估。