A simple method for the detection of unstable haemoglobins

Thrombosis Tendency After Splenectomy in a Danish Family With Hemoglobin Volga, and a Literature Review

Hemoglobin (Hb) Volga is a rare, unstable β-chain hemoglobin variant (β27 Ala→Asp), causing chronic hemolytic anemia. This study presents two members of a Danish family, splenectomized due to Hb Volga at and with multiple thrombotic events. The proband was diagnosed with Hb Volga 9 years old and splenectomy was performed as a part of treatment. Throughout his life, he experienced multiple superficial thrombophlebitis, two episodes of distal deep venous thrombosis (DVT) on lower extremities (age 32 and 33) and a transient ischemic attack (TIA) presented as amaurosis fugax (age 51). Thrombophilia investigation was normal. The proband's son was diagnosed with Hb Volga and underwent splenectomy at the age of 6. Despite anticoagulation therapy, he suffered from multiple venous thromboembolic events in his youth and died of chronic pulmonary embolism (PE)/pulmonary hypertension combined with infection. Given the observed propensity for multiple thromboses in these two patients, a literature review was conducted investigating reported occurrence of thrombotic events in individuals with Hb Volga.

Currently 25 cases of Hb Volga are reported worldwide. The clinical symptoms primarily described are related to hemolytic anemia. Splenectomy is reported in 15 patients. Thromboses have previously been reported in only three patients who were also splenectomized. These cases involved DVT and PE, myocardial infarction, and an unspecified thrombotic event. The proband represents the first reported Hb Volga case with both venous and arterial thrombotic disorders. The exact mechanism underlying thrombotic tendency in patients with Hb Volga remains unknown, but it is probably associated with splenectomy.

The rare hemoglobin variant Hb Mizuho: report of a Swiss family and literature review

Hb Mizuho is a very rare unstable hemoglobin; here, we describe the clinical history of three Swiss family members with Hb Mizuho together with a systematic review of the previously six published cases. The clinical history of the adult woman we report here is unique since this is the first Hb Mizuho presenting with Moyamoya complications and the first case reported with long-term erythrocyte exchange. The literature review showed that Hb Mizuho was mainly reported as a de novo mutation, with the exception of children descended from known cases. All published patients with this unstable hemoglobin showed severe hemolytic anemia with the exception of one; all were regularly transfused. Patients with higher HbF levels might require fewer transfusions. All patients underwent splenectomy at a median age of 4 years and had variable clinical improvement; some achieved complete resolution of transfusion dependency after splenectomy. Iron overload in Hb Mizuho patients seems to be mainly attributed to transfusions and has less to do with ineffective erythropoiesis. Diagnosis might be challenging; a normal hemoglobin electrophoresis should not rule out the diagnosis of unstable hemoglobin in patients with otherwise unexplained hemolytic anemia. This series shows the enormous utility of using molecular techniques for diagnosis.

Evaluation on the separated effect of 13 hemoglobin variants by a new automatic Hba1c analyzer

Objective

To evaluate the effect of a new type of automatic glycated hemoglobin analyzer on the separation of abnormal hemoglobin.

Methods

Samples diagnosed as hemoglobin variants by capillary electrophoresis and gene testing were selected, and HbA1c analyzer was used for separation and detection.

Results

A total of 13 hemoglobin variants in 40 samples could be separated from the normal peaks.

Conclusions

The variant mode of hemoglobin HbA1c can identify a variety of hemoglobin variants, and the type of variants can be preliminarily determined according to the retention time and characteristic peak shape of the variants.

The Importance of Characterizing the Hemoglobin Instability of New Variants: The Case of Hb Dompierre [β29(B11)Gly→Arg, HBB: c.88G>C]

Hb Dompierre [β29(B11)Gly→Arg, HBB: c.88G>C] is a rare β-globin gene variant that was previously described in the heterozygous state in a 24-year-old female patient. It is defined in the HbVar database as being clinically and biologically asymptomatic. A few years after the first description, we had an opportunity of reassessing the index case because she presented with splenomegaly and clinical and biological manifestations of hemolysis. After ruling out the most common causes of hemolysis, further analyses on the variant hemoglobin (Hb) using brilliant cresyl blue staining, indicated that it showed mild instability, which may explain the clinical and biological manifestations. A structural bioinformatic analysis on the Hb variant suggested that the amino acid replacement may be deleterious to the integrity of the Hb. This report confirms the importance of completely characterizing all new Hb variants in order to guide the patients' clinical management and follow-up, as well as to provide the probands and their family members with appropriate genetic counseling.

A Japanese Family with the Unstable Hb Sydney (HBB: c.203T>C) Variant and Persistent Low Hemoglobin Oxygen Saturation

Patients with unstable hemoglobin (Hb), caused by a qualitative abnormality in α- and β-globin genes, are often asymptomatic or mildly symptomatic. It is often difficult to diagnose unstable Hb patients with only mild hemolysis or low oxygen saturation. We herein report a case of a family with an unstable Hb, specifically, Hb Sydney (HBB: c.203T>C), an abnormal β-globin chain. A 5-year-old boy was referred to our hospital for low percutaneous oxygen saturation (SpO₂) in the setting of bronchitis. During hospitalization, low SpO₂ persisted despite the improvement in respiratory distress symptoms. As he had mild hemolysis and splenomegaly, his disease was diagnosed to carry Hb Sydney based on gene analysis. His mother and brother also carried Hb Sydney. In this case, bronchial asthma had been treated, but unstable Hb was not assessed. Low SpO₂ may be tolerated and overlooked in cases of asthma and it took time to diagnose this patient. The present case suggests that unstable Hb should be considered in patients with bronchial asthma and prolonged low SpO₂.

Efficacy of Dichlorophenolindophenol (DCIP) as Screening Test for Hb E: Revisited

Hb E-beta thalassemia is a major public health problem in West Bengal, India and is the predominant symptom producing thalassemia in this part of the country. To search for an easy, reliable and cost effective screening method for HbE that can be used at the community level where more sophisticated methods are not readily available. And the DCIP test was performed for the purpose. Blood samples of 425 asymptomatic family members from 80 diagnosed cases of HbE beta Thalassemia patients were tested for Hb, RBC indices, DCIP test, HPLC, and in discordant cases confirmed by DNA mutation analysis. The present study shows DCIP screening test to have a sensitivity, specificity, positive predictive value and negative predictive value of 96.39%, 97.43%, 96.39% and 97.43% respectively. It also shows a false positive rate and false negative rate in 2.56% and 4.6% cases respectively. The advantage with DCIP over HPLC is that it can be easily performed at the community level by a person with minimum technical skill, few samples (even a single sample) can be tested at time, at a low cost.

Hb Guangxi [β65(E9)Lys→Glu (AAG>GAG); HBB: c.196A>G]: A Novel β-Globin Variant

We report a novel variant found in a female from Guilin municipality in the Guangxi Zhuang Autonomous Region of the People's Republic of China. This variant can be readily detected by both cation exchange high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). Sanger sequencing revealed a novel mutation on the β-globin gene [β65(E9)Lys→Glu (AAG>GAG); HBB: c.196A>G]. We named this novel hemoglobin (Hb) variant Hb Guangxi for the place of origin of the proband.

Compound Heterozygosity for an Unstable Novel Hemoglobin Variant, Hb Dongguan [α52(E1)Ser→Cys (TCT>TGT); HBA1: c.158C>G], and the - -SEA (Southeast Asian) α-Thalassemia Deletion

Here we report a 67-year-old Chinese male carrying an unstable novel hemoglobin (Hb) variant in compound heterozygosity with the - -^SEA (Southeast Asian) α-thalassemia (α-thal) deletion. Hemoglobin analysis by capillary electrophoresis (CE) revealed a rapid degradation feature of the variant. Sanger sequencing of the Hb gene revealed a novel homozygous mutation in exon 2 of the α1-globin gene [α52(E1)Ser→Cys (TCT>TGT); HBA1: c.158C>G]. We named this novel variant Hb Dongguan for the place of origin of the proband. Additionally, gap-polymerase chain reaction (gap-PCR) indicated the presence of the heterozygous - -^SEA α-thal deletion.

Hb Palencia: a novel δβδ-type two-way fusion variant with β-globin-like expression levels

AIMS

Fusion proteins of unequal recombination events at the β-globin locus have pathological effect. The haemoglobin (Hb) variants of type Lepore are fusion proteins characterised by β-like globin chains with a δ-globin (HBD) N-terminus and a β-globin (HBB) C-terminus, whereas reciprocal products of underlying crossover events hold a HBB N-terminus and HBD C-terminus instead. Finally, Hb Parchman contains a β-like globin chain with a central HBB fragment and HBD-derived N-termini and C-termini, whereas reciprocal hybrid proteins are as yet unknown.

METHODS

The propositus was an 80-year-old Caucasian man, whose HbA1c quantification by HPLC (Variant II turbo) for exclusion of type-2 diabetes revealed an abnormal peak. Haemoglobins were analysed by ion-exchange HPLC (Variant II) and capillary electrophoresis (Sebia Capillarys Flex) and DNA by automatic Sanger sequencing of δ-globin and β-globin genes.

RESULTS

Sequencing showed an HBB-HBD-HBB hybrid gene, with HBD-derived central codons 9-31, and HBB-derived UTRs and complementary coding regions. The corresponding new hybrid haemoglobin (Hb Palencia) is represented at ≈40%, similar to HbA.

CONCLUSION

Hb Palencia contains the first globin variant with internal HBD sequences and HBB-derived N-terminal and C-terminal and regulatory sequences. Relative quantity of the new βδβ-type variant suggests transcriptional control by HBB elements and a half-life similar to normal HBB.

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.

Alpha Hemoglobinophaties in Rosario, Argentina

Hemoglobinopathies are the most common recessive diseases worldwide. While the molecular basis of β-thalassemia in Rosario has been addressed, that of α-thalassemia and α structural alterations, has not. In this study 105 individuals from different families referred to our center were investigated for alpha hemoglobinopathies because of low MCV (<85 fL), low MCH (<27 dg), normal HbA2 (≤3.5%) and transferrin saturation of >15%. Six of them with a clinical phenotype of thalassemia intermedia were diagnosed as Hb H disease (five cases) and Hb H like (one case). It also included one patient with sickle cell trait, confirmed by hematological and molecular studies. We were able to identify alpha globin genes mutations in 92 individuals (87.6%): 88 patients with alpha thalassemia, 3 patients with structural alterations and one with both. In total, 13 individuals (12.4%) had no identified α-globin mutation. This study is the first to deal with the molecular basis of α-hemoglobinophaties in Rosario.

Hb San Cataldo [β144(HC1)Lys→Thr; HBB: C.434A > C]: A New Hemoglobin Variant with Increased Affinity for Oxygen

A 59-year-old Italian woman came to our center for revaluation of a previous diagnosis of polycythemia vera. The patient presented with a lifelong history of polycythemia, no increase in white blood cells (WBCs) and platelets, and a negative bone marrow biopsy. Analysis of hemoglobin (Hb) fractions showed an abnormal fast moving Hb component. We aimed to determine if this variant was the cause of polycythemia in this patient. A complete blood count (CBC) was performed by an automated cell counter and Hb fractions were determined by high performance liquid chromatography (HPLC). Standard stability tests and oxygen affinity evaluation were also performed. Genomic DNA was extracted from peripheral blood leukocytes using the phenol chloroform method and the entire β-globin gene was analyzed by direct sequencing. At the hematological level, no anemia or hemolysis was observed but an abnormal Hb fraction was detected using cation exchange HPLC. Molecular analysis of the β-globin gene showed heterozygosity for an AAG > ACG substitution at codon 144, resulting in a Lys→Thr amino acid replacement. We demonstrated that this is a new Hb variant with increased oxygen affinity. Its altered physiology is caused by the reduction of 2,3-diphosphoglycerate (2,3-DPG) effects, due to an amino acid substitution in the central pocket near the C-terminal of the β chain. We called this new variant Hb San Cataldo for the native city of proband.

Diagnostic Dilemma of Hb Perth [β32(B14)Leu→Pro; HBB: c.98T > C] in Mainland China

Unstable hemoglobin (Hb) variants represent a rare etiology of congenital hemolytic anemia. Correct diagnosis can be a challenge due to the relative rarity or lack of awareness of this disorder. We report an 18-month-old girl, who presented with a long-standing hemolytic anemia. Her diagnosis of unstable Hb Perth [β32(B14)Leu→Pro, HBB: c.98T > C] had not been made until gene sequencing of the β-globin gene was performed.

First report of an Asian family with hemoglobin Evans [α2 62 (E11) Val → Met]

Hemoglobin Evans is an unstable variant caused by a single nucleotide mutation that produces a valine-to-methionine substitution at residue 62 of the α-globin chain. It has not been reported in the Asian population and only three cases have been reported worldwide. We diagnosed a Japanese boy with chronic hemolytic anemia with hemoglobin Evans after genetic testing. This is the first familial case of hemoglobin Evans in an Asian population.

Hemoglobin variants: biochemical properties and clinical correlates

Diseases affecting hemoglobin synthesis and function are extremely common worldwide. More than 1000 naturally occurring human hemoglobin variants with single amino acid substitutions throughout the molecule have been discovered, mainly through their clinical and/or laboratory manifestations. These variants alter hemoglobin structure and biochemical properties with physiological effects ranging from insignificant to severe. Studies of these mutations in patients and in the laboratory have produced a wealth of information on hemoglobin biochemistry and biology with significant implications for hematology practice. More generally, landmark studies of hemoglobin performed over the past 60 years have established important paradigms for the disciplines of structural biology, genetics, biochemistry, and medicine. Here we review the major classes of hemoglobin variants, emphasizing general concepts and illustrative examples.

Hb Treviso [α91(FG3)Leu→Phe (α2)]: a new slightly unstable hemoglobin variant with moderately decreased oxygen affinity

We report a new hemoglobin (Hb) variant, found in a North-East Italian family living in the city of Treviso. The proband, a non anemic 60-year-old male with a history of chronic rhinitis, allergy to Parietaria and suspected obstructive sleep apnea syndrome, was referred for blood gas analysis. Determination of the oxygen affinity revealed a p50 of 32.5 mmHg (control 27.5 mmHg) indicating a moderate decrease in oxygen affinity. An abnormal pattern compatible with an α Hb variant was observed on high performance liquid chromatography (HPLC); direct sequencing revealed a transition at codon 91 of the α2 gene (HBA2: c.274C>T) changing leucine into phenylalanine. Characterization and phenotype studies are reported.

Assessment of the red cell proteome of young patients with unexplained hemolytic anemia by two-dimensional differential in-gel electrophoresis (DIGE)

Erythrocyte cytosolic protein expression profiles of children with unexplained hemolytic anemia were compared with profiles of close relatives and controls by two-dimensional differential in-gel electrophoresis (2D-DIGE). The severity of anemia in the patients varied from compensated (i.e., no medical intervention required) to chronic transfusion dependence. Common characteristics of all patients included chronic elevation of reticulocyte count and a negative workup for anemia focusing on hemoglobinopathies, morphologic abnormalities that would suggest a membrane defect, immune-mediated red cell destruction, and evaluation of the most common red cell enzyme defects, glucose-6-phosphate dehydrogenase and pyruvate kinase deficiency. Based upon this initial workup and presentation during infancy or early childhood, four patients classified as hereditary nonspherocytic hemolytic anemia (HNSHA) of unknown etiology were selected for proteomic analysis. DIGE analysis of red cell cytosolic proteins clearly discriminated each anemic patient from both familial and unrelated controls, revealing both patient-specific and shared patterns of differential protein expression. Changes in expression pattern shared among the four patients were identified in several protein classes including chaperons, cytoskeletal and proteasome proteins. Elevated expression in patient samples of some proteins correlated with high reticulocyte count, likely identifying a subset of proteins that are normally lost during erythroid maturation, including proteins involved in mitochondrial metabolism and protein synthesis. Proteins identified with patient-specific decreased expression included components of the glutathione synthetic pathway, antioxidant pathways, and proteins involved in signal transduction and nucleotide metabolism. Among the more than 200 proteins identified in this study are 21 proteins not previously described as part of the erythrocyte proteome. These results demonstrate the feasibility of applying a global proteomic approach to aid characterization of red cells from patients with hereditary anemia of unknown cause, including the identification of differentially expressed proteins as potential candidates with a role in disease pathogenesis.

Identification of the First Japanese Family Harboring a Novel Hemoglobin Variant "Perpignan", Which Caused Low HbA1c Measurement During Diabetic Follow-Up

Hemoglobin A1c (HbA1c) is an important parameter for evaluating long-term (6-8 weeks) control of blood glucose levels in patients with diabetes mellitus. We report a Japanese diabetic case who harbored abnormal Hb and demonstrated falsely low HbA1c levels in the regular ion exchange HPLC-based assay. His abnormal β-globin chain had an amino acid replacement that corresponded to glycine to serine substitution at amino acid position 136 of the β-globin chain (Hb Perpignan). Accordingly, a heterozygotic point mutation replacing guanine by adenine at nucleotide position 406 (β136G > S) was identified in the β-globin gene of the proband and his son. These results indicate that the patient had Hb Perpignan, and this abnormal Hb interfered with the HPLC-based HbA1c assay commonly used in the clinic. The cases presented are the first report of patients in the Japanese population harboring Hb Perpignan (β136G > S).

Hb Baden: structural and functional characterization

Hb Baden (β18Val→Met) is a rare variant hemoglobin that has never been functionally or clinically characterized. We describe a Hb Baden heterozygote who exhibits normal growth and development, as well as age- and gender-appropriate hematological values. Surprisingly, in vitro analyses demonstrate that Hb Baden is relatively unstable and exhibits an abnormally high affinity for O₂. These properties are likely to affect the physiologies of individuals who inherit the β(Baden) mutation in trans to a determinant for either a functionally relevant hemoglobinopathy or a mild thalassemia. The data also provide insights into the function of the A-helix/AB-segment of β globin, supporting a structural model in which this poorly understood region serves as a scaffold that fixes the positions of other helices that directly impact β-globin function.

History and current status of newborn screening for hemoglobinopathies

The impact of hemoglobinopathies on healthcare in the United States, particularly sickle cell disease (SCD), has been significant. Enactment of the Sickle Cell Anemia Control Act in 1972 significantly increased the federal interest in the SCDs and other hemoglobinopathies. Only since May 1, 2006, have all states required and provided universal newborn screening for SCD despite a national recommendation to this effect in 1987. In this article, we review the history of screening for SCD and other hemoglobinopathies, along with federal and state activities that have contributed to improved health outcomes for patients with SCD, as well as current newborn screening practices. We also chronicle the federal activities that have helped to shape and to refine laboratory screening and diagnostic proficiency. Finally, we review molecular testing strategies that have evolved and outline their possible future impacts on disease detection and outcome improvement.

Hemoglobinopathies: a longitudinal study over four decades

BACKGROUND

Hemoglobinopathies are among the most common hereditary diseases worldwide, with high prevalence in the Mediterranean basin, Africa, and Asia. Although they are rare in the indigenous central European population, they have become much more common in Germany recently through the immigration of millions of people from endemic regions.

METHODS

In a long-term study (1971-2007), 100,621 hemoglobin analyses were performed and retrospectively evaluated. Basic clinical and hematological information were provided by the participating physicians. The hemoglobin defects were characterized with hematological and biochemical methods, as well as by DNA analysis in selected cases (from the mid-1980's onward). 73% of the analyses were performed in patients with an immigration background, 27% in patients of German ethnic origin.

RESULTS

34,228 persons, or 34% of those studied, were found to have a hemoglobinopathy. Most cases involved thalassemia syndromes (25,798 cases, 25.6%); the second most common type was a structural abnormality of hemoglobin (8,430 cases, 8.4%). This study provides the first broad overview of the occurrence, spectrum, and geographical distribution of hemoglobinopathies in Germany.

CONCLUSIONS

These data show that hemoglobinopathies are a relevant health problem in the population of Germany today. This is not an epidemiological study, and thus it is unknown to what extent these data are representative. Because hemoglobin defects are of widely diverse genetic and clinical types, specialized laboratory analysis is needed to diagnose them correctly and provide a basis for proper therapeutic decisions.

Co-inheritance of Hb Hershey [beta70(E14) Ala-->Gly] and Hb La Pommeraie [beta133(H11)Val-->Met] in a Sicilian subject

OBJECTIVES

This report represents the first observation in Sicily of two rare beta-globin gene variants, Hb Hershey [beta70(E14) Ala-->Gly] and Hb La Pommeraie [beta133(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 beta- and alpha-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 GCC-->GGC (Hb Hershey) and at codon 133 GTG-->ATG (Hb La Pommeraie) in beta-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 beta-chain haemoglobin variant with increased oxygen affinity: Hb Roma [beta115(g17)Ala-->Val]

BACKGROUND

Haemoglobin Roma [beta115(G17)Ala-->Val] is a new adult haemoglobin variant found in a patient presenting a mild hypochromia and microcytosis. We studied this previously uncharacterised variant in order to evaluate the effect on the structural and funcional properties of the Ala-->Val substitution at the alpha1beta1 interface.

METHODS AND RESULTS

The variant chain was identified by direct DNA sequencing of the beta-globin gene, which revealed a GCC-->GTC mutation in codon 115. This mutation was confirmed by mass spectrometric analysis of the tetramers and peptides. The oxygen-binding properties of the haemoglobin A/haemoglobin Roma mixture, in which the variant makes up 25% of the haemoglobins, showed a significant increase in oxygen affinity with respect to normal haemoglobin A, both in the absence and presence of 2,3-bisphosphoglycerate. The role of the betaG17 position, situated at the alpha(1)beta(1) interface, has been examined using computational models of haemoglobin Roma and other known betaG17 variants, in comparison with normal haemoglobin A.

CONCLUSIONS

This study suggests that the beta115(G17)Ala-->Val substitution at the alpha1beta1 interface is responsible for increased oxygen affinity and mild destabilisation of the haemoglobin Roma.

GENERAL SIGNIFICANCE

An amino acid substitution at the G17 position of the alpha1beta1 interface may result in stabilisation of the high affinity R-state of the haemoglobin molecule.

Description of two new alpha variants: Hb Canuts [alpha85(F6)Asp-->His (alpha1)] and Hb Ambroise Pare [alpha117(GH5)Phe-->Ile (alpha2)]; two new beta variants: Hb Beaujolais [beta84(EF8)Thr-->Asn] and Hb Monplaisir [beta147 (Tyr-Lys-Leu-Ala-Phe-Phe-Leu-Leu-Ser-Asn-Phe-Tyr-158-COOH)] and one new delta variant: Hb (A2)North Africa [delta59(E3)Lys-->Met]

We present here five new hemoglobin (Hb) variants which have been identified during routine Hb analysis before their genotypic characterization. Four of these result from a classical missense mutation: Hb Canuts [alpha85(F6)Asp-->His (alpha1)], Hb Ambroise Pare [alpha117(GH5)Phe-->Ile (alpha2)], Hb Beaujolais [beta84(EF8)Thr-->Asn] and HbA(2)-North Africa [delta59(E3)Lys-->Met]. The last one, Hb Monplaisir [beta147 (Tyr-Lys-Leu-Ala-Phe-Phe-Leu-Leu-Ser-Asn-Phe-Tyr-158-COOH)], results from a frameshift mutation at the stop codon of the beta-globin gene which leads to a modified C-terminal sequence in the beta-globin chain. None of these variants seem to have a particular clinical expression in the heterozygous state. The circumstances of the discovery of these five new Hb variants emphasize the fact that an association of techniques is necessary for a complete screening of Hb variants during routine Hb analysis. Globin chain separation by reversed phase liquid chromatography (RP-LC) appears to be the most relevant method.

Two Unstable β Chain Variants Associated with β-Thalassemia: Hb Miami [β116(G18)His→Pro], and Hb Hershey [β70(E14)Ala→Gly], and a Second Unstable Hb Variant at β70: Hb Abington [β70(E14)Ala→Pro]

We report on three previously undescribed unstable hemoglobin (Hb) variants: Hb Miami, Hb Hershey and Hb Abington. Hb Miami was associated with a beta(+)-thalassemia (thal) mutation [IVS-I-110 (G-->A)], whereas Hb Hershey was associated with a B0-thal mutation [IVS-I-1 (G-->A)]. Hb Hershey also has decreased oxygen affinity. These three Hb variants illustrate the range of clinical severity that can be seen with unstable Hb variants, particularly when combined with a thalassemic mutation.

Hemoglobin variants in Cyprus

Cyprus, located at the eastern end of the Mediterranean region, has been a place of eastern and western civilizations, and the presence of various hemoglobin (Hb) variants can be considered a testimony to past colonizations of the island. In this study, we report the structural Hb variants identified in the Cypriot population (Greek Cypriots, Maronites, Armenians, and Latinos) during the thalassemia screening of 248,000 subjects carried out at the Thalassaemia Centre, Nicosia, Cyprus, over a period of 26 years. A sample population of 65,668 people was used to determine the frequency and localization of several of the variants identified in Cyprus. The localization of some of the variants in regions where the presence of foreign people was most prevalent provides important clues to the origin of the variants. Twelve structural variants have been identified by DNA sequencing, nine concerning the beta-globin gene and three concerning the alpha-globin gene. The most common beta-globin variants identified were Hb S (0.2%), Hb D-Punjab (0.02%), and Hb Lepore-Washington-Boston (Hb Lepore-WB) (0.03%); the most common alpha-globin variant was Hb Setif (0.1%). The presence of some of these variants is likely to be directly linked to the history of Cyprus, as archeological monuments have been found throughout the island which signify the presence for many years of the Greeks, Syrians, Persians, Arabs, Byzantines, Franks, Venetians, and Turks.

Five variants of the beta-globin gene without clinical or hematological effects: Hb Maryland [beta 47(CD6)Asp-->His], Hb Kent [beta 37(C3)Trp-->Cys], Hb Visayan [beta 136(H14)Gly-->Cys], Hb Cutlerville [beta 138(H16)Ala-->Val] and Hb Hornchurch [beta 43(CD2)Glu-->Lys]

We report on five hemoglobin (Hb) beta chain variants that were initially identified either by electrophoretic, chromatographic or isoelectric focusing (IEF) methods. These variants do not appear to be associated with clinical or hematological abnormalities. All variants were confirmed by DNA sequence analysis.

Novel hemoglobin alpha chain elongation resulting from a 15-residue insertion and tandem duplication of the F helix

OBJECTIVES

To determine the cause of an unusual hemoglobin pattern with two novel components eluting after HbA(2) on cation exchange HPLC. This variant was detected during HbA1c measurement and was associated with a normal blood count and a positive isopropanol test.

DESIGN AND METHOD

Whole hemolysate and isopropanol precipitates were analysed by ESI MS, and individual components were purified by reverse phase and cation exchange HPLC. Tryptic peptide mapping of isopropanol precipitates was used to detect the molecular lesion and DNA sequencing was used to characterise the precise rearrangement.

RESULTS

ESI MS showed a mass increase of 1614Da in 9% of the alpha globin chains and sequence analysis of the alpha2 gene revealed the heterozygous insertion of 45 nucleotides after codon 93. The predicted in phase incretion of ALSALSDLHAHKLRV (+ 1613Da) is a direct repeat of residues alpha79-93 and signature ions from the new peptide were clearly visible in peptide maps of the unstable hemoglobin.

CONCLUSION

The insertion probably results from replication slippage during DNA synthesis and the 15-residue repeat results in full repetition of the heme-linked F helix. The nature of the inserted sequence explains the molecular instability and the electrophoretic mobility, but not the twin peaks observed on cation exchange HPLC. These components had the same chain composition, (alpha(L) beta), the same number of heme groups per chain, were not in rapid equilibrium with each other, and probably represent hemoglobin species with different conformers of the elongated alpha(L) chain.

Hb J- Meerut [alpha 120 (H3) Ala ->Glu (alpha1)] in a Turkish male

Hb J Meerut is an infrequently found alpha-globin variant. It has previously been reported in various populations around the world. One particular case reported in 1994 included a Turkish family. In this report, details of a second case of Hb J Meerut in a Turkish male who is unrelated to the first family are described. In the present case a slight increase in the oxygen affinity of Hb J Meerut, relative to that of the normal control, has been observed as detected by low p50 values in arterial whole blood. Additionally, a slight increase in red blood cell count, as compared against a normal individual, was observed.

A family with hemoglobin Hirosaki

A 48-year-old man had a 30-year history of hemolytic anemia of undetermined cause. Spherocytes were not observed, osmotic fragility was normal, and red cell enzyme activities were normal. His brother and daughter also had hemolytic anemia. The brother had previously undergone splenectomy, and the anemia had been ameliorated. In the proband and daughter, no abnormal hemoglobin was apparent in the results of isoelectric focusing and DEAE anion-exchange high-performance liquid chromatography analyses. On evaluation with the isopropanol test, unstable hemoglobin was not observed in the proband but was detected in the daughter. There was also a decreased ratio of 3 globin/3 globin chain production. Analysis of the 32 gene demonstrated the presence of a mutation (alpha43 [CE1] Phe --> Leu), hemoglobin Hirosaki.