Fast hemoglobin variant in Minahassan people of Sulawesi, Chinese and Thais: alpha-2-beta-2 56 Gly-Asp

Hemoglobin J Manado was found in 1957 in the father and two children of a Minahassan family originating from Manado, Northern Sulawesi, Indonesia. Present studies demonstrate that the structural anomaly in J Manado is located in the βT5 section of the hemoglobin molecule; the glycyl group normally found at the β-56 position, or the βD7 position of the D-helix, is replaced by an aspartyl group. Previous work had established that the same structural change occurs in Hemoglobin J Meinung, seen in Chinese residents of Taiwan, as well as in Hemoglobin J Korat or J Bangkok found in Thai subjects. The origins and ethnic background of the Minahassan people are obscure; their relatively large stature, light complexion, and language serve to set them from all other groups in Indonesia as well as Southeast Asia. They have no apparent ethnic connection either with Chinese or Thais, however, because of the relative geographical proximities of the three groups it appears likely that the occurrence of the same hemoglobin variant within all three can be explained by gene flow rather than by separate mutations.     

Hemoglobin New York in Chinese subjects in Taiwan

Hemoglobin K Kaohsiung has been found, during our population survey in Taiwan, in nine unrelated Chinese subjects with provincial origins from several parts of Mainland China and Taiwan. It also was seen in four relatives of the nine subjects. Present chemical structure studies indicate that it has the same structural anomaly as that previously reported in a variant found in members of a Cantonese Chinese family in New York. That variant, called Hemoglobin New York, has the structural change, β113 Valine→Glutamic acid. Preliminary evaluation suggests that this hemoglobin is one of the most common variants in Chinese population groups although it frequently may be undetected by the usual electrophoretic screening procedures. All of the subjects detected thus far were heterozygotes with nearly equal amounts of Hemoglobin A_o and K Kaohsiung. Hemoglobin K Kaohsiung exhibits slightly reduced heat stability compared with that of Hemoglobin A_o; however, its presence in the heterozygote apparently causes no more than mild anemia.     

Hemoglobin Athens-Georgia, or alpha 2 beta 2 40(C6)Arg replaced by Lys, a hemoglobin variant with an increased oxygen affinity.

A new hemoglobin variant, termed hemoglobin Athens-Georgia, has been found in a 23-year-old Caucasian student and three members of her family. The electrophoretic mobility of this variant at pH 9.0 is slightly less than that of hemoglobin-A. Arginyl residue in position 40 of the beta chain, corresponding to position 6 of the C helix, has been replaced by a lysyl residue. This amino acid substitution is at the alpha1-beta2 contact and slightly affects the oxygen binding properties of the hemoglobin molecule. Hemoglobin Athens-Georgia has an increased affinity for oxygen, a normal heme-heme interaction and a normal Bohr effect. Hematological abnormalities are not associated with this variant.     

Hemoglobin Fannin-Lubbock [alpha2 beta 2 119 (GH2) Gly replaced by Asp]. A new hemoglobin variant at the alpha1 beta 1 contact.

Hemoglobin Fannin-Lubbock was found in a 9-year-old Mexican-American female. The abnormal hemoglobin was detected as a fast-moving variant by electrophoresis on cellulose acetate at pH 8.4. Structural analysis indicated a substitution in the beta-chain of aspartic acid for glycine at position 119, a position involved in the alpha1beta1 contact of the hemoglobin tetramer. This contact between unlike chains is larger and undergoes a smaller shift during the process of oxygenation and deoxygenation that the alpha1beta2 contact (Perutz, M.F., Muirhead, H., Cox, J.M. and Goaman, L.C.G. (1968) Nature 219, 131-139). Mutations in this contact tend to cause slight or no changes in functional behavior. Apart from a mild anemia, the propositus did not exhibit any obvious clinical symptoms.     

A new hemoglobin variant. HB Yatsushiro alpha 2 A beta 2 60 Val replaced by Leu

This study was performed to establish the structural abnormality of a new hemoglobin variant discover-d in a Japanese patient with angina pectoris. The hybridization of the separated hemoglobin with canine hemoglobin revealed a beta-chain anomaly. Peptide betaTp-6 was found to be abnormally located on the peptide map of tryptic digests of the S-carboxymethylated beta-chain from the variant hemoglobin. A structural study on the abnormal betaTp-6 revealed that the variant hemoglobin differs from hemoglobin A by substitution of leucine for valine at residue 60 of the beta-chain. This new variant hemoglobin is designated as hemoglobin Yatsushiro after the name of the city where the propositus lived. The patient is hematologically healthy and his clinical history has nothing to do with this abnormal hemoglobin.     

Hemoglobin Atlanta or alpha 2 beta 2 75 Leu-Pro (E19): an unstable variant found in several members of a Caucasian family.

Hemoglobin Atlanta, alpha 2 beta 2 75 Leu-Pro (E19), has been found in several members of three generations of a Caucasian family living in metropolitan Atlanta. The abnormal hemoglobin is one of the nine unstable variants in which either a leucyl or an alanyl residue is replaced by a prolyl residue. These substitutions have been observed in the B, E, F, and G helixes of the beta chain and in the H helix of the alpha-chain. Hemoglobin Atlanta heterozygotes are mildly affected by the presence of this unstable hemoglobin.     

Hemoglobin Tilburg: alpha 2-beta 2 73 (E 17) Asp----Gly. A new hemoglobin with reduced oxygen affinity

A new hemoglobin variant has been found in a Dutch Caucasian girl and detected also in members of three generations of her family. This variant is characterized by the substitution of an aspartic acid at position 73 (E 17) of the beta-chain with a glycine residue. Hemoglobin Tilburg makes up to 42% of the total hemoglobin in the blood of the proposita, it is stable at the isopropanol test, and not associated with significant hematological abnormalities in heterozygous carriers. The oxygen dissociation curve of the purified variant, carried out at different pH values, shows a definite reduction of the affinity for oxygen and a normal alkaline Bohr effect. Three more hemoglobins with a single amino acid substitution at the same site have been previously described: Hb Korle-Bu (Asp----Asn), Hb Mobile (Asp----Val) and Hb Vancouver (Asp----Tyr). In all these proteins the affinity for oxygen is lowered to an extent which is variable and characteristic of each mutant. In this paper we discuss the possible mechanism responsible for the abnormal behaviour of hemoglobins substituted at beta 73.     

Alloalbuminemia in North India.

Electrophoretic screening of sera from 550 individuals from Punjab, North India, revealed four cases of alloalbuminemia. Two albumin variants migrated slower and two migrated faster than the common albumin A. These variants were further analyzed by electrophoresis of their cyanogen bromide fragments to localize their molecular differences. One of the slow variants appears similar to, if not identical with, albumin B, with an altered cyanogen bromide fragment CNBr VII. The other slow variant appears to be a new variant (proposed name albumin Punjab) differing from albumin A in an altered fragment CNBr VI (which also occurs in albumins Kashmir and Adana) and in an altered fragment CNBr I. Among the fast variants, one has the same altered fragment CNBr V as albumin Naskapi, while the other appears to be a new variant (proposed name albumin Patiala) having an altered fragment CNBr VI. The presence of albumin Naskapi in Punjabis, North American Indians, and Eti Turks (previously reported) is consistent with the existence of a common ancestral population in which the mutation to Naskapi occurred before the migrations eastward and westward.     

A new hemoglobin variant: HB yatsushiro α2Aβ260Val→Leu

This study was performed to establish the structural abnormality of a new hemoglobin variant discovered in a Japanese patient with angina pectoris.The hybridization of the separated hemoglobin with canine hemoglobin revealed a β-chain anomaly. Peptide βTp-6 was found to be abnormally located on the peptide map of tryptic digests of the S-carboxymethylated β-chain from the variant hemoglobin. A structural study on the abnormal βTp-6 revealed that the variant hemoglobin differs from hemoglobin A by substitution of leucine for valine at residue 60 of the β-chain.This new variant hemoglobin is designated as hemoglobin Yatsushiro after the name of the city where the propositus lived. The patient is hematologically healthy and his clinical history has nothing to do with this abnormal hemoglobin.     

Hemoglobin Dallas (alpha 97(G4)Asn-->Lys): functional characterization of a high oxygen affinity natural mutant.

Hemoglobin Dallas, an alpha-chain variant with a substitution of lysine for asparagine at position 97(G4), was found to have increased oxygen affinity (p1/2 = 1 mmHg at pH 7.3 and 20 degrees C), diminished cooperativity (n, the Hill coefficient = 1.7) and reduced Bohr effect (about 50%). Addition of allosteric effectors (such as 2,3-diphosphoglycerate, inositol hexakisphosphate and bezafibrate) led to a decrease in oxygen affinity and increase in cooperative energy. Kinetic studies at pH 7.0 and 20 degrees C revealed that (i), the overall rate of oxygen dissociation is 1.4-fold slower than that for HbA and (ii), the carbon monoxide dissociation rate is unaffected. The abnormal properties of this hemoglobin variant can be attributed to a more 'relaxed' T-state.     

Hemoglobin types of Brazilian Indians

Starch gel and paper electrophoresis determinations were performed in the bloods of 532 Indians and 123 Mestizos. The individuals tested belong to the Aweikoma, Caingang, Guarani, Xavante and Cayapo tribes and live in several places in Southern, Central and Northern Brazil. No abnormal types were observed in the putatively “pure blood” individuals; among the Mestizos only one AS person was found. Data concerning the hemoglobin types of Indians living in eight other South American countries are also reviewed.     

gamma-Aminobutyric acid transaminase (GABAT) polymorphism among ethnic groups in Singapore--with report of a new allele.

gamma-Aminobutyric acid transaminase (GABAT, E.C.2.6.I.19) was phenotyped by starch-gel electrophoresis in post-mortem liver samples from 650 unrelated subjects of either sex, comprising 289 Chinese, 177 Indians, 140 Malays, and 44 from other racial groups from Southeast Asia. The estimated gene frequencies of GABAT1 and GABAT2 were found to be .5779 and .3806 in Chinese, .5678 and .3955 in Indians, and .6214 and .3250 in Malays. The frequency of GABAT1 was .5909 in the mixed group of other races. There was no significant difference in the phenotypic distribution between sexes. A new slow (less anodal) variant (GABAT3) has been observed in low frequency in all the groups (.0415, .0367, 0536, and 0536, and .0568 in Chinese, Indians, Malays, and the mixed-group, respectively). The distribution of GABAT phenotypes was at Hardy-Weinberg equilibrium in all the ethnic groups studied.     

MICA polymorphism in South American Indians

We have studied the MICA alleles of 196 unrelated subjects from three South American Indian tribes (Toba, Wichi and Terena). They are members of isolated tribes located in the Gran Chaco area in northeastern Argentina and in Mato Grosso do Sul in South Central Brazil. Of 55 previously known alleles, nine were observed in South American Indians, compared with 16 that were found in North American Caucasians, suggesting a more restricted allelic distribution of MICA in these tribes. In South American Indians, MICA*00201 was the most frequent allele, with a gene frequency of 33% in Toba, 47% in Wichi and 44% in Terena. MICA*00201, MICA*027 (external domain sequence like MICA*008/TM allele A5) and MICA*010 accounted for more than 90% of all the MICA genes in South American Indians. In North American Caucasians, MICA*00801 (*008/A5.1) accounted for 42% of the genes and was the most common allele. We observed a high degree of linkage disequilibrium between certain alleles of MICA and of HLA-B in the South American Indian populations. Phylogenetic trees constructed using gene frequencies of the transmembrane short tandem repeats in the populations reported here, and in other populations taken from published reports, suggest that South American Indians are more closely related to Asians than to Europeans.     

Properties of hemoglobin G. Ferrara (beta57(E1) Asn replaced by Lys).

Hemoglobin G. Ferrara is an abnormal human hemoglobin in which an asparagine residue is replaced by a lysyl residue at position beta57 (beta57 Asn replaced by Lys). Oxygen equilibria show that cooperativity and alkaline Bohr effect are maintained to normal levels while the acid Bohr effect appears increased; in addition, a smaller effect of diphosphoglycerate is also observed. Flash photolysis experiments performed as a function of protein concentration show that the fraction of quickly reacting form is always higher than that of human hemoglobin A. This fact, together with the increase of the oxygen affinity observed at acid pH values, may be related to an enhanced dissociation of the molecule into dimers. Several attempts to isolate the native chains by treatment of the protein with p-chloromercuribenzoate were unsuccessful due to the great instability of the isolated variant beta-chains, which precipitated completely during incubation with p-chloromercuribenzoate. Therefore, although the substitution is on the surface of the molecule, there are several properties of hemoglobin G. beta Ferrara which are clearly different from hemoglobin A.     

Functional and subunit assembly properties of hemoglobin Alberta (alpha 2 beta 2(101) Glu----Gly)

Hemoglobin Alberta has an amino acid substitution at position 101 (Glu----Gly), a residue involved in the alpha 1 beta 2 contact region of both the deoxy and oxy conformers of normal adult hemoglobin. Oxygen equilibrium measurements of stripped hemoglobin Alberta at 20 degrees C in the absence of phosphate revealed a high affinity (P50 = 0.75 mm Hg at pH 7), co-operative hemoglobin variant (n = 2.3 at pH 7) with a normal Bohr effect (- delta log P50/delta pH(7-8) = 0.65). The addition of inositol hexaphosphate resulted in a decrease in oxygen affinity (P50 = 8.2 mm Hg at pH 7), a slight increase in the value of n and an enhanced Bohr effect. Rapid mixing experiments reflected the equilibrium results. A rapid rate of carbon monoxide binding (l' = 7.0 X 10(5) M-1 S-1) and a slow rate of overall oxygen dissociation (k = 15 s-1) was seen at pH7 and 20 degrees C in the absence of phosphate. Under these experimental conditions the tetramer stability of liganded and unliganded hemoglobin Alberta was investigated by spectrophotometric kinetic techniques. The 4K4 value (the liganded tetramer-dimer equilibrium dissociation constant) for hemoglobin Alberta was found to be 0.83 X 10(-6) M compared to a 4K4 value for hemoglobin A of 2.3 X 10(-6) M, indicating that the Alberta tetramer was less dissociated into dimers than the tetramer of hemoglobin A. The values of 0K4 (the unliganded tetramer-dimer equilibrium dissociation constant) for hemoglobin Alberta and hemoglobin A were also measured and found to be 2.5 X 10(-8) M and 1.5 X 10(-10) M, respectively, demonstrating a greatly destabilized deoxyhemoglobin tetramer for hemoglobin Alberta compared to deoxyhemoglobin A. The functional and subunit dissociation properties of hemoglobin Alberta appear to be directly related to the dual role of the beta 101 residue in stabilizing the tetrameric form of the liganded structure, while concurrently destabilizing the unliganded tetramer molecule.     

Hemoglobin tilburg: α2-ß2 73 (E 17) Asp→Gly: A new hemoglobin with reduced oxygen affinity

A new hemoglobin variant has been found in a Dutch Caucasian girl and detected also in members of three generations of her family. This variant is characterized by the substitution of an aspartic acid at position 73 (E 17) of the ß-chain with a glycine residue. Hemoglobin Tilburg makes up to 42% of the total hemoglobin in the blood of the proposita, it is stable at the isopropanol test, and not associated with significant hematological abnormalities in heterozygous carriers. The oxygen dissociation curve of the purified variant, carried out at different pH values, shows a definite reduction of the affinity for oxygen and a normal alkaline Bohr effect. Three more hemoglobins with a single amino acid substitution at the same site have been previously described: Hb Korle-Bu (Asp→Asn), Hb Mobile (Asp→Val) and Hb Vancouver (Asp→Tyr). In all these proteins the affinity for oxygen is lowered to an extent which is variable and characteristic of each mutant. In this paper we discuss the possible mechanism responsible for the abnormal behaviour of hemoglobins substituted at ß 73.     

Letter: Equilibrium and kinetic studies of hemoglobin I: a functionally silent amino acid substitution at an invariant residue;

Hemoglobin I is an uncommon hemoglobin variant in which the lysine residue at position 16 of the a chain has been replaced by glutamic acid. Lysine is the invariant residue in all myoglobin and hemoglobin subunits that have been sequenced, with the exception of the hemoglobin of the lamprey. Replacement of invariant residues is generally reflected in altered functional properties of the hemoglobin molecule and such invariance may be indicative of a unique functional role. However, a study of the oxygen equilibrium and kinetic properties of hemoglobin I showed the functional properties of this hemoglobin to be indistinguishable from those of normal adult hemoglobin.     

Hemoglobin S and some other hemoglobinopathies in Eti-Turks

Frequencies of various hemoglobinopathies were examined in a total of 1,922 individuals of Eti-Turk origin by electrophoretical techniques. Hemoglobin A2 (Hb A2) and hemoglobin F (Hb F) determinations were also performed in 651 and 1,642 cases, respectively. Mean hemoglobin S (Hb S) frequency was found to be 15.3%. Variations among the different age groups were insignificant. Hemoglobin E (Hb E) and beta-thalassemia frequencies wer 0.47 and 1.23%, respectively. Hemoglobin Hacettepe and hemoglobin D were found once. Red cell glucose-6-phosphate dehydrogenase (G6PD) deficiency was found in 6.5% of males.     

The interleukin-6 (-174) G/C promoter polymorphism is associated with type-2 diabetes mellitus in Native Americans and Caucasians

Chronic low-grade activation of the immune system may play a role in the pathogenesis of type-2 diabetes mellitus (T2DM). Interleukin-6 (IL6), a powerful inducer of hepatic acute phase response, has been implicated in the etiology of insulin resistance and T2DM. Recently, an IL6 promoter polymorphism (G/C) at position -174 was found to be associated with measures of insulin sensitivity. Because we have previously found an association between high IL6 levels and insulin resistance in both Pima Indians - a population with high rates of insulin resistance and T2DM - and Caucasians, we aimed to assess whether the IL6 promoter polymorphism is associated with T2DM in these populations. We genotyped the IL6 (-174) G/C polymorphism using pyrosequencing in 463 Native Americans and by PCR-RFLP in 329 Spanish Caucasians. Among the Spanish Caucasian subjects, there was a significant difference in genotypic distribution between diabetic and non-diabetic subjects (P=0.028); the GG genotype was more common in diabetic (0.40) than in non-diabetic (0.29) subjects. The G allele was much more frequent in the Native American sample, and among a sample of 143 cases and 145 controls, the GG genotype was significantly more common in diabetic subjects (P=0.019). When this sample population was stratified according to ethnic heritage, all 211 subjects who were of full Pima Indian heritage had the GG genotype, whereas in the 77 American Indian subjects with non-Pima admixture, T2DM was associated with IL6 genotype (P=0.001). These findings are consistent with a role for genetic determinants of inflammation in the development of T2DM in both Native Americans and Caucasians.     

Structural, functional, and subunit assembly properties of hemoglobin Attleboro [alpha 138 (H21) Ser----Pro], a variant possessing a site maturation at a critical C-terminal residue

Hemoglobin Attleboro, a new alpha-chain variant with a substitution of proline for serine at position 138 (H21), was found to be a noncooperative high-affinity hemoglobin (P50 = 0.26 mmHg at pH 7 and 20 degrees C) which lacked an alkaline Bohr effect. Addition of 2,3-diphosphoglycerate (DPG) or inositol hexaphosphate (IHP) led to a decrease in oxygen affinity but to no alteration in either Bohr effect or cooperativity. Ligand binding kinetics studies revealed an overall rate of oxygen dissociation at pH 7.0 and 20 degrees C that was 2.7-fold slower than that for Hb A. At pH 8.5, the kinetic profile was identical with that at pH 7, confirming the absence of a Bohr effect for this variant hemoglobin. Measurement of the rate of oxygen dissociation with carbon monoxide replacement indicated a lack of cooperativity. Sedimentation velocity experiments yielded s20,w values of 2.8 and 4.3 for 65 microM solutions of oxyhemoglobins Attleboro and A, respectively (indicating an enhancement in the oxy dimer population of this variant). Studies of the carbon monoxide combination of this variant revealed an association rate 20-fold faster than that for Hb A; only in the presence of a 1000-fold molar excess of IHP was there a significant reduction in the overall rate. Rapid-scan and traditional stopped-flow experiments conducted in the Soret Soret region demonstrated an alteration in the structure and rate of assembly of the deoxy tetramer of Hb Attleboro relative to that of Hb A. The abnormal properties of this hemoglobin variant can be attributed to major perturbations in the C-terminal region.