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Hemoglobin Savannah (B6(24) beta-glycine is greater than valine): an unstable variant causing anemia with inclusion bodies.

An abnormal hemoglobin, termed Hb Savannah, was found in red cell hemolysate of a young Caucasian girl with severe hemolytic anemia. The presence of this unstable variant became evident when inclusion bodies appeared rapidly upon exposure of red cells to redox dyes and a large percentage of hemoglobin in hemolysate precipitated on warming to 65 degrees C. Treatment of the hemoglobin with p-hydroxymercuribenzoate (PMB) caused a rapid dissociation into monomers; starch-gel electrophoresis of PMB-treated hemoglobin showed the presence of abnormal beta-chains. Data from structural studies of isolated beta-chains indicated substitution of a valyl residue for the normally occurring glycyl residue at position 24, which corresponds to helical residue B6. A similar substitution but with an arginine replacing the glycyl residue has been observed in Hb Riverdale-Bronx. The glycine to valine substitution will change the relationship of the B and the E helices which results in extensive conformational changes in the beta-chain. This change presumably causes an increased dissociation of the hemoglobin molecule into dimers and probably monomers, and a decreased stability of the alphabeta-dimers. The hemoglobin abnormality may be the result of a fresh mutation because the abnormality is not present in the parents nor in any of the seven siblings.

Amino Acid Sequence↗

[Rare hemoglobins in Guadeloupe and in the Lesser Antilles (author's transl)].

Screening of abnormal hemoglobins on 25 136 samples allowed us to detect from 1974-1979 rare or uncommon hemoglobins as N Baltimore, Korle Bu, Lepore, K Woolwich, J Broussais and J Baltimore. Hemoglobins N Baltimore, J Broussais, and J Baltimore are detected for the first time in Guadedoupe. The identification of these asymptomatic hemoglobins in this part of the Carribbean region provides information concerning the exact origin of the black population of these islands; e.g., hemoglobin K Woolwich and N Baltimore are found only in specific regions of West Africa.

Fetal Hemoglobin↗

Homozygosity for Hb E-Saskatoon [beta22(B4)Glu-->Lys] in a Turkish patient.

A 30-year-old female who is homozygous for a Hb E-like abnormal hemoglobin and her immediate relatives were studied. Clinical examination of the proband revealed no abnormality. Routine hematological analysis showed that her hemoglobin level was 12 g/dL, MCV 82 fL, MCH 28 pg, RDW 15%. DNA sequence analysis indicated the presence of a G-->A substitution at codon 22 corresponding to an abnormal hemoglobin, namely Hb E-Saskatoon [beta22(B4)Glu-->Lys (GAA-->AAA)]. Absence of any abnormalities in clinical and routine hematological investigations of the homozygous patient indicated that the phenotypical expression of the Hb E-Saskatoon is very mild. Using a reverse transcription-polymerase chain reaction technique, the alpha/beta and betaX/betaA-mRNA (X = Hb E-Saskatoon) ratios were determined. Normal alpha/beta and betaX/betaA-mRNA ratios were found in the homozygous patient and in all heterozygotes, indicating that the respective mutation did not alter the stability of the mRNA. FokI restriction enzyme analysis of the polymerase chain reaction products obtained from the genomic DNA and/or beta-globin mRNA made it possible for rapid diagnosis of Hb E-Saskatoon, and for its differentiation from Hb E [beta26(B8)Glu-->Lys (GAG-->AAG)]. Analysis of the restriction fragment length polymorphism (RFLP) in the beta-globin gene complex of the index patient and of another unrelated family with a compound heterozygosity for Hb E-Saskatoon and beta-thalassemia revealed that the Hb E-Saskatoon mutation shared a common allele.

Adult↗

[Primary structure of abnormal E-like hemoglobin].

An E-like abnormal hemoglobin was detected in a hematological patient and one of the members of her family. The composition of blood hemolyzates was characterized using acetate cellulose electrophoresis. The abnormal beta-chain was isolated by ion-exchange chromatography of total globin on CM-cellulose. Using peptide mapping of the abnormal beta-chain trypsin hydrolysates, it was shown that the amino acid substitution occurs in peptide beta T3. The amino acid analysis and determination of the abnormal fragment C-terminal amino acid allowed to establish the locus and type of this substitution. The first case of hemoglobin E(alpha 2 beta 2 26Glu leads to Lys) identification on the territory of the USSR is reported.

Amino Acid Sequence↗

The association of Hb Stanleyville II with alpha thalassemia and Hb S.

Two unrelated families are described which include two heterozygotes for Hb Stanleyville II, two compound heterozygotes for Hb Stanleyville II and Hb S, and one compound homozygote for the two abnormal hemoglobins. The homozygote did not produce normal alpha chains, the abnormal chains accounted for 32-35% of the total alpha chain of four heterozygotes, and the alpha/non-alpha synthetic ratios were in the range 0.59-0.77. These data demonstrate the presence of an alpha-thalassemia gene linked to the alpha-Stanleyville II mutation.

Adult↗

First observation of homozygous hemoglobin hamadan (B 56 (D7) GLY-ARG) and beta thalassemia (-29 G>A)- hemoglobin Hamadan combination in a Turkish family.

During screening surveys for beta thalassemia and abnormal hemoglobins in Mugla, a city located in the Aegean Region of Turkey, a hemoglobin variant was detected in two large families residing in two neigboring cities (i.e., Muğla and Aydin) without any clinical signs. Further analysis of the variant revealed it as Hb Hamadan (B 56 (D7) GLY-ARG). Family screening revealed the father of the propositus as homozygote Hb Hamadan. The grandfather of the index case was detected as combination of Hb Hamadan with beta thalassemia. The beta thalassemia carrier had a promotor mutation at -29 G>A, which is also a novel mutation. Furthermore, we described a simple and rapid restriction enzyme digestion protocol (Hha I) for the verification of Hb Hamadan. The clinical and hematologic data of the index case and his father showed that neither homozygous Hb Hamadan nor combination with beta thalassemia has clinical importance. This is also important especially from the prenatal diagnosis point of view.

DNA Mutational Analysis↗

Characterization of a new electrophoretically silent hemoglobin variant. Hb saale OR alpha 2beta 2 84(EF8)Thr --> Ala.

A new abnormal hemoglobin was detected in a young German anemic patient by cation-exchange high performance liquid chromatography (HPLC). Using a combination of electrospray mass spectrometry, HPLC, direct sequencing, and family screening with polymerase chain reaction/restriction digestion approach, we have characterized this hemoglobin variant as resulting from a Thr --> Ala replacement at beta84(EF8). It could be separated neither by electrophoresis nor by isoelectric focusing. Hb Saale is slightly unstable, exhibiting a moderate tendency to auto-oxidize. Functional properties and the heterotropic interactions are similar to those of Hb A.

Adult↗

Isoelectric focusing of human hemoglobin: its application to screening, to the characterization of 70 variants, and to the study of modified fractions of normal hemoglobins.

Isoelectric focusing on slabs of acrylamide gel was adapted for the screening of abnormal hemoglobins, the characterization of 70 human variants, and the study of minor fractions of normal hemoglobin. The screening method was as fast and inexpensive as conventional techniques, allowed the simultaneous analysis of some 50 samples of whole blood, and yielded resolution superior to that obtained by other methods with hemolysates. Among the 70 variants, 31 mutants could not be separated from HbS by cellulose acetate electrophoresis. The characterization technique of electrofocusing allowed us to distinguish between most variants. Only one mutant, Hb Galveston, could be confused with HbS. Hb Köln, the most frequent unstable mutant, exhibited a special pattern. HbA1C was separated from HbA. Preliminary results indicate that quantitation of HbA1C by gel scanning is feasible.

Electrophoresis, Cellulose Acetate↗

Heme structures of five variants of hemoglobin M probed by resonance Raman spectroscopy.

The alpha-abnormal hemoglobin (Hb) M variants show physiological properties different from the beta-abnormal Hb M variants, that is, extremely low oxygen affinity of the normal subunit and extraordinary resistance to both enzymatic and chemical reduction of the abnormal met-subunit. To get insight into the contribution of heme structures to these differences among Hb M's, we examined the 406.7-nm excited resonance Raman (RR) spectra of five Hb M's in the frequency region from 1700 to 200 cm(-1). In the high-frequency region, profound differences between met-alpha and met-beta abnormal subunits were observed for the in-plane skeletal modes (the nu(C=C), nu(37), nu(2), nu(11), and nu(38) bands), probably reflecting different distortions of heme structure caused by the out-of-plane displacement of the heme iron due to tyrosine coordination. Below 900 cm(-1), Hb M Iwate [alpha(F8)His --> Tyr] exhibited a distinct spectral pattern for nu(15), gamma(11), delta(C(beta)C(a)C(b))(2,4), and delta(C(beta)C(c)C(d))(6,7) compared to that of Hb M Boston [alpha(E7)His --> Tyr], although both heme irons are coordinated by Tyr. The beta-abnormal Hb M variants, namely, Hb M Hyde Park [beta(F8)His --> Tyr], Hb M Saskatoon [beta(E7)His --> Tyr], and Hb M Milwaukee [beta(E11)Val --> Glu], displayed RR band patterns similar to that of metHb A, but with some minor individual differences. The RR bands characteristic of the met-subunits of Hb M's totally disappeared by chemical reduction, and the ferrous heme of abnormal subunits was no longer bonded with Tyr or Glu. They were bonded to the distal (E7) or proximal (F8) His, and this was confirmed by the presence of the nu(Fe-His) mode at 215 cm(-1) in the 441.6-nm excited RR spectra. A possible involvement of heme distortion in differences of reducibility of abnormal subunits and oxygen affinity of normal subunits is discussed.

Carbon↗

Isolation and functional characterization of hemoglobin Casper: beta106(G8) Leu replaced by Pro.

Hemoglobin Casper (beta106Leu replaced by Pro) can be separated from hemoglobin (Hb) A by isoelectric focusing on polyacrylamide gel. This abnormal hemoglobin was estimated to be 30% of teh total by both isoelectric focusing and heat lability kinetics. Its oxygen equilibrium curves indicate a high oxygen affinity, low degree of subunit interaction, and a decreased Bohr effect. Mixtures of Hb Casper and Hb A appear to bind oxygen as if no hybrid molecules exist.

Diphosphoglyceric Acids↗

Hemoglobin Roseau-Pointe a Pitre alpha 2 beta 2(90) (F6) Glu----Gly: a new hemoglobin variant with slight instability and low oxygen affinity.

A Dominican neonate carrying a new abnormal hemoglobin, hemoglobin Roseau Pointe-à-Pitre alpha 2 beta 2(90)(F6) Glu----Gly, was detected in Guadeloupe during application of a cord blood screening program. This variant behaved in isoelectrofocusing as an Hb D, and displayed instability and low whole blood oxygen affinity. In the affected family it was present, either isolated, or in association with a beta+ thalassemia trait.

Electrophoresis, Polyacrylamide Gel↗

A fusion gene in man: DNA sequence analysis of the abnormal globin gene of hemoglobin Miyada.

An abnormal globin gene from a patient heterozygous for Hemoglobin Miyada was cloned and sequenced. The results indicated that the 5' flanking region and the 5' side of the gene were identical to those of a beta-globin gene and that the 3' side was identical to that of a delta-globin gene. The part of the gene identical to a beta-globin gene shifted to the part identical to the delta-globin gene somewhere in a homologous sequence region between the third nucleotide of the 17th codon and the second nucleotide of the 22nd codon of these two genes. Thus, results of analysis of the nucleotide sequence support the idea that the abnormal globin gene of Hemoglobin Miyada was generated as a fusion gene by unequal crossing over between a beta- and a delta-globin gene.

Amino Acid Sequence↗

Diminished synthesis of an alpha chain mutant, hemoglobin I (alpha-16 lys leads to glu).

In patients heterozygous for abnormal hemoglobins there is usually less than 50% of the mutant hemoglobin present in peripheral blood. The synthetic rates of alpha-chain mutants compared to alpha(A) have not been reported to date. In this study the production of alpha(A)- and alpha(I)-chains has been measured in peripheral blood and bone marrow of two patients with approximately 30% hemoglobin I, an alpha-chain abnormality (alpha(16 lys --> glu)). The results suggest that the decreased amount of alpha(I) compared to alpha(A) is due solely to diminished biosynthesis of the alpha(I)-chains. The relative rates of synthesis of alpha(I)- and alpha(A)-chains are similar in both nucleated red cells and reticulocytes indicating that no change occurs during erythroid cell maturation which preferentially affects either alpha(I) or alpha(A) production.

Adult↗

Comparative analysis of glycosylated hemoglobins by ion-exchange column chromatography and high-performance liquid chromatography in patients with hemoglobinopathies.

Cation-exchange chromatography gives falsely decreased values for glycosylated hemoglobins (GHbs) in patients with abnormal hemoglobins (Hbs) such as S, D, G, C, E, and O. This decrease is thought to be proportional to the percentage of abnormal Hb present. In the authors' study, cation-exchange column chromatographic GHb values on 84 nondiabetic patients heterozygous for Hb S, 28 AS diabetic patients, and 23 nondiabetic patients heterozygous for Hb C were calculated to account for the percentage of abnormal Hb, and the resulting values were compared with the GHb values obtained by high-performance liquid chromatography (HPLC). There existed a good correlation between the calculated GHb and the GHb obtained by HPLC (r = 0.92 for AS and r = 0.94 for AC). In patients with elevated Hb F, chromatographic GHb values are falsely high. In such cases, correction can be made by subtracting the Hb F value from the observed GHb. In laboratories where cation exchange chromatography is used, accurate determination of GHb can be made by adjusting observed values for portion of the abnormal Hb present.

Chromatography, High Pressure Liquid↗

Hemoglobin Setif and in vitro pseudosickling noted in a family with co-existent alpha and beta thalassemia.

A Turkish Cypriot family was investigated for suspected heterozygous sickle cell disease, which had been reported in a maternal branch of the family resident in England. Two maternal grandparents were of African Negro origin. Pseudosickling was noted in members of the family who were found to have an abnormal hemoglobin fraction. This abnormal fraction proved to be Hemoglobin Setif (alpha 94 Asp leads to Tyr). Family studies demonstrated the presence of this hemoglobin in varying proportions in the mother and 2 of the 4 children. alpha and beta thalassemia traits are also present in several family members.

Adolescent↗

Expression of hemoglobin E in newborn.

Hemoglobin E(HbE) is an abnormal hemoglobin resulted from a point mutation in codon 26 (GAG-AAG) of beta-globin gene. The mutation causes an amino acid substitution (Glu-Lys) and abnormal splicing in exon 1 that reduce the amount of beta E chain synthesis. While in adult, the HbE can easily be diagnosed, its level in newborn is usually underrepresent. In this study, we examined a relationship between genotype of HbE and the amount of HbE in cord blood. 145 Cord blood specimens were analysed by starch gel electrophoresis and the amounts of HbE were determined by microcolumn chromatography. The zygosity of beta E globin gene was determined by the polymerase chain reaction. The levels of HbE were 3.17 +/- 1.79% for 59 heterozygotes, 8.55 +/- 2.52% for 3 homozygotes and 0.48 +/- 0.22% in 83 normal newborns. This result provides useful data for a neonatal screening program and implies that expression of HbE in newborn dependent on a copy number of beta E globin gene in each individual.

Adult↗