Hb S [β6(A3)Glu→Val, GAG>GTG] and β-globin gene cluster haplotype distribution in Mauritania

Of 1050 Mauritanian blood donors screened from the two main racial groups, i.e., the Moors and Black Africans, 60 were found to carry Hb S [β6(A3)Glu→Val, GAG>GTG], giving a global frequency of 5.71%. The prevalence observed in the Black African Mauritanians (10.69%) is almost five times that found in the Moor group (2.25%). Four of the five main β(S) haplotypes were detected in this study: Senegal (77.8%), Benin (8.8%), Arab-Indian (5.5%) and Bantu (4.4%). These data showed that Hb S is a serious public health problem in Mauritania. They also confirm the ethnic heterogeneity of the Mauritanian population.     

Hb S [β6(A3)Glu→Val, GAG>GTG] in Mexican Mestizos: frequency and analysis of the 5' β-globin haplotype

Between 1978 and 2009, we studied 1,863 Mexican Mestizo patients with clinical data compatible with a hemoglobinopathy. Of these patients, 382 had some hemoglobin (Hb) abnormality (20.5%), 128 had a sickle cell hemoglobinopathy, representing a general frequency of 6.9%, which is similar to the percentage observed in previous studies on Mexican Mestizos. We analyzed the 5' β-globin haplotype (5'Hp) in 79 unrelated β(S) chromosomes (26 β(S)/β(S), 14 β(S)/β(Thal), nine β(S)/β(A) and four β(S)/β(D)), and four haplotypes were observed: 72.2% CAR 24.1% Benin, 2.5% Senegal and 1.2% Cameroon; the last two are reported for first time in Mexico. In some Latin American populations such as Brazil, the Bantu haplotype predominates, while in others such as Jamaica, the Benin haplotype is the most frequent, showing heterogeneity of African genes as a consequence of different regions involved in the slave trade.     

The first case of Hb G-Honolulu [α30(B11)Glu→Gln (GAG>CAG); HBA2:c.91G>A] observed in association with Hb S [β6(A3)Glu→Val, GAG>GTG] in a healthy Italian child

We report the first observation of Hb G-Honolulu [α30(B11)Glu→Gln (GAG>CAG); HBA2:c.91G>A] in a Caucasian family and the first case of this variant to be found in association with Hb S [β6(A3)Glu→Val, GAG>GTG]. The proband was a healthy 4-year-old Italian boy. His chromatographic hemoglobin (Hb) pattern showed an abnormal peak having the typical retention time of Hb S (25.6% ), a second abnormal peak eluted soon after (13.6%) and a third minor peak eluted at the end of the run (6.5%). Identification of Hb variants were performed by peptide mapping using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Two abnormal peptides at m/z 765.1 and 922 were found, corresponding to the αT-4 and βT-1 peptides characteristic for Hb G-Honolulu and Hb S, respectively. The third minor abnormal peak presumably corresponded to the hybrid molecule (α(G-Honolulu)/β(S)). The concomitant presence of Hb G-Honolulu and Hb S does not seem to produce any relevant clinical manifestation.     

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.     

Surface Plasmon Resonance-Based Molecular Detection of Hb S [β6(A3)Glu→Val,GAG→GTG] at the Gene Level

The surface plasmon resonance (SPR) approach, being a relatively novel biophysical method, is used to detect many different targets by biomolecular interaction. The SPR system uses optical and evanescent wave phenomenon. This approach does not need any labels, such as enzymes or isotopes, and the monitored interactions are in real time. In DNA-DNA interaction, the SPR approach is Tm-independent. Here we report our preliminary results for the molecular detection of the Hb S (GAG →GTG) mutation at codon 6 of the human β-globin gene. Our preliminary results show that the SPR approach could be applied as an inexpensive and fast routine test system for the molecular diagnosis of abnormal hemoglobins (Hbs), especially in premarital screening programs.     

Compound Heterozygosity for Hb S [β6(A3)Glu→Val,GAG→GTG] and a New Thalassemic Mutation [β132(H10)Lys→Term,AAA→TAA] Detected in a Family from West Africa

We describe a Hb S/β-thalassemia (β-thal) mutation involving an A→T transition at codon 132 of the β-globin gene. The mutation, in the heterozygous state, unlike several other mutations in exon 3, shows no signs of dominant thalassemia but those of a typical β⁰ carrier. Compound heterozygosity with Hb S [β6(A3)Glu→Val, GAG→GTG] showed a severe clinical picture.     

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.     

Hb Agenogi [β90(F6)Glu→Lys (GAG>AAG) HBB: c.271G>A)] in a Pregnant Thai Woman

Hb Agenogi [β90(F6)Glu→Lys (GAG>AAG) HBB: c.271G>A)] is a very rare β-globin chain variant. We report for the first time this hemoglobinopathy in a pregnant 20-year-old Thai woman. She was seen by an obstetrician at her 14th week of gestation. She was pale and had an inflammatory lesion of her lower left leg. The hemoglobin (Hb) analysis by high performance liquid chromatography (HPLC) and low pressure liquid chromatography (LPLC) showed a peak of abnormal Hb at the C window. On capillary electrophoresis (CE), the abnormal Hb peak was observed at electrophoretic zone 4 that corresponded to the Hb E (HBB: c.79G>A) peak. Direct DNA sequencing revealed a GAG>AAG mutation at codon 90 of the β-globin gene. Thus, even though Hb Agenogi is very rare, it can be found in Thai people. The knowledge and understanding of this hemoglobinopathy will be used to assist in diagnosis, management and counseling for patients.     

Hb Koln [β98(FG5) [GTG → ATG,Val → Met]: The first report from India

Background

The group of unstable hemoglobins are associated with congenital non-spherocytic hemolytic anemia due to instability of the hemoglobin molecule. They often lead to formation of the characteristic inclusion bodies or Heinz bodies.

Aim

To identity the cause of mild anemia, reticulocytosis, and hepatosplenomegly in a case of non-spherocytic hemolytic anemia.

Materials and methods

A 34-year-old female patient originating from Maharashtra, western India presented with mild anemia and jaundice which had persisted since childhood. Investigations included a complete blood count, screening for red cell membrane protein defects, Hb analysis by high-performance liquid chromatography (HPLC) and cellulose acetate electrophoresis (pH 8.9), heat instability test and DNA sequencing.

Results

Hemoglobin analysis by HPLC showed an abnormal peak in the Hb C window (9.8%) with a retention time of 4.90 minutes. Cellulose acetate electrophoresis (pH 8.9) showed a slow moving band (6.15%) between Hb A₂ and Hb S. The heat instability test was positive. DNA analysis of α globin genes showed absence of both deletional and non- deletional α thalassemia. DNA sequencing of the β globin gene revealed heterozygosity for a mutation at codon 98 [GTG → ATG, Val → Met], which gives rise to Hb-Koln.

Conclusion

Hb Koln is the commonest unstable Hb variant reported from many populations in the world. However, this is the first report of this unstable Hb variant from India.     

Compound heterozygosity for Hb S [β6(A3)Glu→Val] and Hb Kenya (Aγ81Leu-β86Ala) in a Ugandan woman

Hb Kenya is a hemoglobin (Hb) tetramer composed of two normal α- and two non α-globin chains. The latter are the product of a fusion gene in which the 5' end is (A)γ and the 3' end is β. The crossover point is between codon 81 of the (A)γ gene and codon 86 of the β gene. Like the other non α genes, the hybrid protein product ((A)γ81Leu-β86Ala) has 146 amino acids. The purpose of this report is to highlight the laboratory findings of Hb Kenya and to emphasize the pitfalls in misdiagnosis, particularly when associated with another variant such as Hb S [β6(A3)Glu→Val].     

Hb L'Aquila [β106(G8)Leu→Val,CTG→GTG]: A Novel Thalassemic Hemoglobin Variant

A new β-globin variant at codon 106 (CTG→GTG), and which we named Hb L'Aquila [β106(G8)Leu→Val], was detected by DNA analysis. The proband and her father presented with the features of a mild β⁺-thalassemia (thal), confirmed by their α/β-globin chain biosynthesis ratios.     

Complex interaction of hemoglobin (Hb) Nakhon Ratchasima [α63(E12)Ala→Val], a novel α2-globin chain variant with Hb E [β26(B8)Glu→Lys] and a deletional α(+)-thalassemia

Objectives: To describe the hematological and molecular features as well as diagnostic aspects of a complex hemoglobinopathy caused by interaction of a novel α2‐globin chain variant with hemoglobin (Hb) E and α⁺‐thalassemia. Methods: Blood specimen of a 41‐yr‐old Thai man was transferred to our center for the analysis of unknown Hb variant. Hb analysis was carried out using automated high‐performance liquid chromatography (HPLC) and capillary electrophoresis system. Mutation was identified by PCR and related techniques. Results: RBC analysis revealed a mild anemia but blood indices were within normal ranges. Hb‐HPLC analysis demonstrated, in addition to the Hb E and Hb A, two abnormal peaks not fully separated from Hb A and Hb E, but capillary electrophoresis showed a pattern of Hb E heterozygote with 4.0% Hb A₂. DNA analysis of the α2 globin gene identified a novel mutation (namely Hb Nakhon Ratchasima), GCC (Ala)→GTC (Val) at codon 63 in trans to the α⁺‐thalassemia (3.7‐kb deletion). Association of this novel α‐chain variant with β^E globin chain leads to the formation of another novel Hb derivative with different HPLC characteristics. Conclusion: Although Hb Nakhon Ratchasima might be clinically innocuous, differential diagnosis from other clinically relevant hemoglobinopathies is essential in routine setting. This could be made by using a simple PCR–restriction fragment length polymorphism assay or allele‐specific PCR assay developed in this study.     

Combination of Hb Heze [β144(HC1)Lys→Arg; HBB: c.434A>G] and β0-Thalassemia in a Chinese Patient with β-Thalassemia Intermedia

We first report a novel β chain variant, Hb Heze [β144(HC1)Lys→Arg; HBB: c.434A>G], in a Chinese family. Heterozygous inheritance of the mutation results in a mild β-thalassemia (β-thal) phenotype, whereas compound heterozygosity of Hb Heze with β⁰-thal appears as the cause of β-thal intermedia (β-TI) in our case.     

Five Variants of the β-Globin Gene without Clinical or Hematological Effects: Hb Maryland [β47(CD6)Asp→His], Hb Kent [β37(C3)Trp→Cys], Hb Visayan [β136(H14)Gly→Cys], Hb Cutlerville [β138(H16)Ala→Val] and Hb Hornchurch [β43(CD2)Glu→Lys]

We report on five hemoglobin (Hb) β 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.     

Hb Extremadura [β64(E8)Gly→Ser;β133(H11)Val→Leu]: a new molecular analysis

Unstable hemoglobin (Hb) variants account for 9.5% of structural hemoglobinopathies. The majority of these unstable variants are the result of gene point mutations resulting in the substitution of a single amino acid by another. The presence of two mutations in the same allele is infrequent: of the 781 variants of the β-globin cluster described, only 32 are due to two point mutations (4.1%). Hb Extremadura is a structural variant that is included within the so-called unstable Hb anomalies. It was first described in 1989, employing the most up-to-date techniques available at that time, reversed phase high performance liquid chromatography (HPLC) to separate the abnormal chain (β(X)) digesting it with trypsin and analysis of the fragments with an automatic analyzer.     

Hb Hinwil [β38(C4)Thr→Asn,ACC>AAC] Associated with β0-Thalassemia in a Sicilian Child

Hemoglobins (Hbs) with high oxygen affinity play a well-known role among the causes of erythrocytosis. In 1996, a new Hb called Hb Hinwil or β38(C4)Thr→Asn was described. In carriers, it causes an increase in the number of red blood cells, total Hb, and hematocrit. Here we report the case of a patient, aged 10 months, whom we observed because of severe erythrocytosis. The family history of β-thalassemia (β-thal) inheritance, and the evidence in the patient of marked microcytosis, prompted us to perform molecular analysis to detect β gene mutations that revealed a codon 39 (C>T) (β⁰) mutation in the heterozygous state and the presence of the Hb Hinwil mutation on the other allele. We discuss diagnostic, clinical, prognostic, and therapeutic aspects of this rare condition, underlining the extreme difficulty in choosing therapeutic options because of a lack of similar reports in the literature.     

A Novel β-Globin Gene Mutation: Hb Shenzhen [β90(F6)Glu→Ala,HBB: c.272A>C]

Abstract

We report a novel β-globin chain variant, Hb Shenzhen [β90(F6)Glu→Ala, HBB: c.272A>C], in a 52-year-old Chinese individual. The hemoglobin (Hb) variant takes the position of the Hb D zone using capillary electrophoresis. Sanger sequencing revealed a novel base mutation on the β-globin gene, HBB: c.272A>C, that resulted in a transition of glutamic acid to alanine at exon 2 of the β-globin gene. We named this novel variant Hb Shenzhen for the geographic origin of this proband.     

Hemoglobin Hofu or αβ [126 (H4) Val → Glu] Found in Combination with Hemoglobin S

Hb Hofu, αβ[126 (H4) Val → Glu], was found in 10 members of 2 apparently unrelated Valmiki families in central India. None showed evidence of hemolysis and hemoglobin levels were normal in most. In two individuals, Hb Hofu occurred in combination with Hb S, but neither had clinical manifestations of sickle cell disease. In samples containing Hb Hofu, the isopropanol precipitation test was positive. Quantitation of the hemoglobin fractions by DEAE-cellulose chromatography showed that Hb Hofu constituted a mean of 23-25% of the total whether in combination with Hb A or Hb S.     

Complex Interaction of Hb E [β26(B8)Glu→Lys], Hb Korle-Bu [β73(E17)Asp→Asn] and a Deletional α-thalassemia-1 in Pregnancy

A pregnant Thai woman with mild hypochromic microcytic anemia caused by α- and β- globin defects is described. The proband was a 26-year-old pregnant woman discovered through our ongoing thalassemia screening program. Initial hemoglobin (Hb) high performance liquid chromatography (HPLC) analysis revealed a homozygosity for an unknown variant at the D window, inconsistent with results of family analyses. Further Hb analysis using automated capillary zone electrophoresis identified that the proband was in fact a compound heterozygote for Hb E [β26(B8)Glu→Lys, GAG>AAG] and another β chain variant. DNA analysis demonstrated that she carried the Hb Korle-Bu mutation [β73(E17)Asp→Asn (GAT>AAT)] in trans to the Hb E and an α-thalassemia-1 (α-thal-1) with the Southeast Asian (? ?^SEA) deletion. Family studies identified that her father and sister were double heterozygotes for Hb Korle-Bu and α-thal-1, whereas her mother was a double heterozygote for Hb E/Hb Constant Spring [Hb CS; α142, Term→Gln (TAA>CAA in α2)]. The genotype-phenotype relationship observed in this Thai family with complex hemoglobinopathies and methods for characterization are presented.