[A new hemoglobin C with sickling: hemoglobin C Ziguinchor. Its discovery and observation in an African Senegalese family].
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Adult↗
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Acceleration of hemoglobin C crystallization by hemoglobin S.
We previously reported that circulating hemoglobin (Hb) CC erythrocytes contain oxygenated HbC crystals with little or no HbF and that HbF inhibits in vitro crystallization of HbC. We now report that HbS accelerates in vitro crystallization of HbC. Crystals were formed in 1.8 mol/L potassium phosphate buffer, pH 7.4, at 30 degrees C and were counted in several time intervals with a hematocytometer. The hemoglobin composition of Millipore-isolated crystals and supernatant were also analyzed. Under the conditions selected, 100% HbS formed needle-shaped crystals only after two hours. Pure HbC does not form crystals within 15 minutes, whereas a ratio of 10% HbS:90% HbC forms 1,100 crystals/mm3, 20% HbS:80% HbC forms 370 crystals/mm3, and 30% HbS:70% HbC forms 5 crystals/mm3. Crystals formed in the presence of HbS are tetragonal, as are pure HbC crystals. As compared with 100% HbC, HbA or albumin mixed with HbC showed a decreased number of crystals as a result of dilution. Analysis of the Hb content of isolated crystals by citrate agar gel electrophoresis showed that HbS was rapidly incorporated into the crystal in the same ratio over time. These results demonstrate that HbS accelerates crystallization of HbC with respect to the rates of crystallization of any of these two Hbs separately, through a mechanism that involves cocrystallization. These results may be significant in understanding SC disease.
Crystallization↗
The inhibition of hemoglobin C crystallization by hemoglobin F.
We have reported that circulating CC erythrocytes containing HbO2 C crystals exhibit little or no Hb F suggesting that Hb F may inhibit the crystallization of Hb C. We report now that Hb F inhibits in vitro crystallization of HbO2 and HbCO C when compared to the effect of Hb A in a wide range of mixture proportions. For example, while HbCO C solutions form tetragonal C crystals within 25 min, no crystals form within 2 h with 30% Hb F, whereas 550 crystals/mm3 form with 30% Hb A. Furthermore, an increase in the percent of Hb A is correlated with a greater number of orthorhombic crystal formation rather than the tetragonal morphology observed with 100% Hb C. We also report that Hb A2 (containing delta chains that exhibit 10 sequence differences with beta chains) and Hb Lepore Boston-Washington (a fusion mutant of delta and beta chains that contains only six of these differences) both inhibit Hb C crystallization. By comparing the sequences of the three inhibitory hemoglobins, we conclude that position Gln-87 in the gamma chains is, at least partially, the cause of the inhibitory effect of Hb F on the crystallization of Hb C.
Amino Acid Sequence↗
Characteristics of the volume- and chloride-dependent K transport in human erythrocytes homozygous for hemoglobin C.
In human red cells homozygous for hemoglobin C (CC), cell swelling and acid pH increase K efflux and net K loss in the presence of ouabain (0.1 mM) and bumetanide. We report herein, that K influx is also dependent on cell volume in CC cells: cell swelling induces a marked increase in the maximal rate (from 6 to 18 mmol/liter cell X hr) and in the affinity for external K (from 77 +/- 16 mM to 28 +/- 3 mM) of K influx. When the external K concentration is varied from 0 to 140 mM. K efflux from CC and normal control cells is unaffected. Thus, K/K exchange is not a major component of this K movement. K transport through the pathway of CC cells is dependent on the presence of chloride or bromide; substitution with nitrate, acetate or thiocyanate inhibits the volume- and pH-dependent K efflux. When CC cells are separated according to density, a sizable volume-dependent component of K efflux can be identified in all the fractions and is the most active in the least dense fraction. N-ethylmaleimide (NEM) markedly stimulates K efflux from CC cells in chloride but not in nitrate media, and this effect is present in all the fractions of CC cells separated according to density. The persistence of this transport system in denser CC cells suggests that not only cell age, but also the presence of the positively charged C hemoglobin is an important determinant of the activity of this system. These data also indicate that the K transport pathway of CC cells is not an electrodiffusional process and is coupled to chloride.
Chlorides↗
Hemoglobin C in association with hereditary persistence of fetal hemoglobin.
Hemoglobin C and hereditary persistence of fetal hemoglobin (HPFH) are an uncommon combination of hemoglobinopathies. Several tests are needed to verify this condition, among them hemoglobin electrophoresis and Kleihauer-Betke staining of a peripheral blood smear. Family studies are useful in delineating the genetics of the hemoglobinopathy but could not be performed in our case. In more confusing cases or with an unusual subtype, more extensive testing may be required. HPFH, by itself, is without clinical manifestations. It may be confused with other conditions; therefore, its presence in patients with hematologic symptoms requires more precise definition of the hemoglobin abnormality.
Adult↗
A case with both hemoglobins C and N-Baltimore.
Hemoglobins C and N-Baltimore were detected in a 75-year-old black man. Although mild anemia and abnormal erythrocyte morphology resembling thalassemia were present, detection of this combination of hemoglobins at an advanced age suggests that it does not limit normal activities.
Aged↗
Vasoocclusion with homozygous hemoglobin-C disease.
Hemoglobin-CC is a relatively uncommon hemoglobinopathy, seen primarily in the black population. These patients usually have a mild clinical course, without significant risk of vasoocclusive crises. There are no routine recommendations for preparation prior to surgery. We present a patient who developed a clinical picture suggestive of major vasoocclusion after cardiac by-pass surgery. In retrospect, these signs appear to be the result of hemodynamic instability and cardiogenic shock instead of vasoocclusion.
Aortic Valve Stenosis↗
Low proportions of glycosylated hemoglobin associated with hemoglobin S and hemoglobin C.
Using a cation-exchange chromatographic method, we found normal or subnormal values for glycosylated hemoglobin in a few diabetic patients with persistent hyperglycemia. Subsequent investigations revealed that these unexpected results had originated from black patients with diabetes. In view of common occurrence of abnormal hemoglobins in the Negro population, we subjected blood preparations to electrophoresis on cellulose acetate and acrylamide gel. The results have shown the presence of hemoglobin S or hemoglobin C in each patient. When allowance was made for the percentage of the abnormal hemoglobin, the "corrected values" of glycosylated hemoglobin increased to the diabetic range. Furthermore, the corrected values agreed well with the "expected values" calculated from a regression line correlating fasting blood glucose concentrations and proportions of glycosylated hemoglobin in more than 300 diabetics with no evidence of hemoglobinopathy. We conclude that in diabetic patients presenting with hemoglobin S or hemoglobin C, there is a considerable decrease in the values for glycosylated hemoglobin as measured by cation-exchange chromatographic methods, and that this decrease is proportional to the percentage of the abnormal hemoglobin.
Blood Glucose↗
Hemoglobin J Guantanamo [alpha 2 beta 2 128 (H6) Ala----Asp] in association with hemoglobin C and alpha-thalassemia in a family from Benin.
Hemoglobin J (HbJ), Guantanamo, which had been described but once in the literature, was found in a family originating from Benin; this second case was found to be in association with hemoglobin C (HbC) and alpha-thalassemia. High-performance liquid chromatography (HPLC) procedures and microsequencing were used for characterization of the aminoacid substitution. The main hematological disorder, in relation with the instability of Hb J Guantanamo, seems to be a worsening of the rheological properties of the red blood cells (RBC), as demonstrated by ektacytometric studies. Oxygen-binding properties of the RBC were almost normal, but a slight decrease in cooperativity and lowered Bohr and 2,3-diphosphoglycerate (DPG) effects were observed for pure stripped Hb J Guantanamo. The expression of the electrophoretic charge difference was partly masked, as is often observed when the structural abnormality is situated in or near a contact area.
Amino Acid Sequence↗
The distinct pathobiology of sickle cell-hemoglobin C disease. Therapeutic implications.
The data available clearly establish that the hyperconcentration of hemoglobin C and S inside SC cells is the main and driving mechanism for the pathologic behavior of these cells. It facilitates the polymerization of Hb S, but it also favors the tendency of Hb C to induce the formation of crystals and aggregates, abnormal morphologic shapes, and abnormally dense reticulocytes, through a particularly active K:Cl cotransport. Why these cells are endowed with a particularly active K:Cl cotransport is still a mystery; it is disproportionate with the extent of the hemolysis and the number of young cells. Is there an abnormal interaction between Hb C and the K:Cl cotransport protein in the inner aspect of the membrane? Are there abnormal interactions between Hb C and the other transport mechanisms that balance the shrinking capacity of K:Cl cotransport (as Na/H exchange)? Only future work will tell. In any case, SC disease is unique among the hemoglobinopathies in that a single intervention could correct all abnormalities: the restitution of the normal MCHC, as proven experimentally by Fabry et al. Hence, effort should be centered on looking for compounds that increase red cell volume, because in SC cells, increases in volume will not distort the cell, but restore it to the normal red cell volume and the normal red cell shape. This luxury is not available for cells with normal MCHC (the majority of the red cells in SS blood), because increasing their volume will progressively turn them into spheres, a rheologically disadvantaged shape.
Animals↗
Sickle cell trait, hemoglobin C trait, and Burkitt's lymphoma.
In a controlled study in Ghana, the hemoglobin electrophoretic pattern in 112 patients with Burkitt's lymphoma was compared to that of their nearest neighbor controls of the same age, sex, and tribe, as well as their sibling controls. Analysis of the data obtained did not show any statistically significant protective advantage for sickle cell trait against Burkitt's lymphoma. Hemoglobin C trait appeared to offer a slight protective advantage (p less than 0.1), but this did not reach statistical significance. These results do not disprove the malaria co-factor hypothesis in the etiology of 0urkitt's lymphoma, but deprive it of an additional indirect evidence in its favor.
Anemia, Sickle Cell↗
Use of specific fluorescent antibodies for the identification of hemoglobin C in erythrocytes.
Antibodies against hemoglobulin C (alpha2beta2 6Glu leads to Lys) were produced by immunizing horses and were purified by affinity chromatography. As expected from the bivalency of both the antibody and the antigen, the purified antibodies failed to produce immunoprecipitates upon reaction with the corresponding antigens. Identification of hemoglobin C in individual erythrocytes was achieved by reacting the fluorescein isothiocyanate-conjugated antibodies with the hemoglobin antigen in fixed smears of peripheral blood. Red cells from persons having a hemoglobin C gene were labeled strongly upon reaction with anti-Hb C-FITC; there was no labeling of red cells containing normal hemoglobins or Hb S, suggesting that the anti-Hb C antibodies recognize only the amino-terminal segment of the beta chains that contain lysine in position beta6.
Animals↗
The role of hemoglobins C, S, and Nbalt in the inhibition of malaria parasite development in vitro.
The host cell competence of hemoglobin C (HbC)-containing erythrocytes for Plasmodium falciparum was studied by in vitro culture. HbC homozygous red cells did not support the growth of the intracellular parasite. Heterozygous cells, however, were competent. In addition, HbC increased the resistance of sicle cell hemoglobin (HbS) red cells when present in the double heterozygote, SC, cultured at low oxygen tension. This effect most likely resulted from the ability of HbC to enhance the sickling of HbS-containing red cells. Oxygenated SC cells were indistinguishable from normal and AS cells in host cell competence. Another double heterozygote, SNBalt, showed decreased sickling and decreased resistance to malaria parasite growth. The evolutionary significance of these results is discussed.
Animals↗
Rheological evaluation of hemoglobin S and hemoglobin C hemoglobinopathies.
The concept of optimum hematocrit was used to compare the rheology of bloods from patients with various hemoglobin S and hemoglobin C hemoglobinopathies. The technique involved the utilization of cone and plate viscometric data to predict average flow rates under representative physiological-fluid mechanical conditions. The shape of the curve relating optimum hematocrit to oxygen tension, rather than the absolute magnitude of the optimum hematocrit at fixed oxygen tension, is shown to give an indication of clinical severity of the disease.
Adolescent↗
Hemoglobin C--G-Georgia double heterozygosity: a case report.
A 12-month-old black female with an unremarkable past medical history was admitted to the hospital with respiratory distress and fever without identified sepsis. Despite mechanical ventilation, the patient died as a result of respiratory insufficiency secondary to severe necrotizing bronchitis and bronchiolitis with pneumonia. Electrophoretic and biochemical analyses of the patient's hemoglobin showed the patient to be a double heterozygote for hemoglobin C (a beta chain variant) and hemoglobin G-Georgia (an alpha chain variant). This is the first report of this combination of hemoglobin variants.
Electrophoresis↗
Severe mycoplasma pneumonia with pleural effusions in a patient with sickle cell-hemoglobin C(SC) disease. Case report and review of the literature.
We describe a patient with sickle cell hemoglobin C(SC) disease in whom severe pneumonia developed complicated by large bilateral pleural effusions and respiratory failure. Mycoplasma infection was not initially suspected but was subsequently proved serologically. The course of the illness was unusually long. A review of the literature showed occurrence of large pleural effusions to be infrequent for pulmonary infection with Mycoplasma in adults, with only eight such cases previously reported. The possibility of Mycoplasma pneumonia should not be dismissed merely because of the severity of the illness or the presence of pleural effusions.
Adolescent↗
[Hemoglobin C associated with beta thalasemia and familial eosinophilia: study of a Chilean kindred (author's transl)].
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Adult↗
Hematuria and hemoglobin C trait.
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Female↗