Mutant, unstable hemoglobins precipitate as Heinz bodies in circulating red blood cells resulting in their premature hemolysis. We stress that generally these hemoglobins contain amino acid substitutions in the β-chain of globin near the heme pocket, and demonstrate that heme binding suffers thereby. Four genetically unstable hemoglobins lost roughly half their heme content while precipitating into Heinz bodies. Conversely, repletion of hemes in vitro corrected the characteristically aberrant electrophoretic mobilities of these hemoglobins and concomitantly prevented their excessive denaturation into Heinz bodies. From the finding that heme-containing α-chains accumulate in solution during Heinz body formation, we propose that heme loss occurs predominantly from mutant β-chains, which then precipitate. This mechanism of Heinz body formation is valid in most, but not all, the unstable hemoglobinopathies.

Unstable Hemoglobins: The Role of Heme Loss in Heinz Body Formation (PDF)

“The presence of a haemoglobin variant with high oxygen affinity would usually lead to polycythaemia, unless the high-affinity haemoglobin is also very unstable, e.g. Hb Koln. In fact, about one-third of unstable haemoglobins show an increased oxygen affinity. However, since the dominant feature is haemolysis rather than polycythaemia, they are categorized as unstable haemoglobin rather than as high-affinity haemoglobin.”

http://www.fmshk.com.hk/hkabth/em/dec2001.htm

http://www.freepatentsonline.com/20050267032.html

“The term “sickle cell disease” means a red blood cell disorder characterized by the presence of one or more mutated hemoglobin genes. Exemplary mutated hemoglobin genes include, for example, .beta..sup.6Glu.fwdarw.Val (Hemoglobin S), .beta..sup.6Glu.fwdarw.Lys (Hemoglobin C), .beta.2.sup.6Glu.fwdarw.Val (Hemoglobin E), .beta..sup.98Val.fwdarw.Met (Hemoglobin Koln), .beta..sup.99Asp.fwdarw.Hi- s (Hemoglobin Yakima), .beta..sup.102Asn.fwdarw.Lys (Hemoglobin Kansas), or combinations thereof. Sickle cell diseases include, for example, sickle cell trait (the heterozygous state of hemoglobin S), sickle cell anemia (the homozygous state of hemoglobin S), hemoglobin SC disease (hemoglobin S present with hemoglobin C), hemoglobin SD disease (hemoglobin S present with hemoglobin D), S/.beta..degree. thalassemia (hemoglobin S with a .beta..degree. thalassemia mutation), and S/.beta..sup.+ thalassemia (hemoglobin S with a .beta..sup.+ thalassemia mutation). Current treatments for sickle cell diseases include, for example, administration of compounds such as antisickling agents (e.g. hydroxyurea), erythropoietin, and/or antibiotics (e.g. ceftriaxone and erythromycin), and allogenic bone marrow transplantation.”

“Most of the abnormal hemoglobins with increased oxygen affinity manifest themselves by causing polycythemia in the carrier. The increased oxygen affinity reduces tissue oxygen delivery, causing an increase in erythropoietin secretion and in red cell mass. The possibility of an abnormal hemoglobin with high oxygen affinity should be considered in those atypical patients with polycythemia in which the white blood cell and platelet counts are not elevated and splenomegaly is absent. The importance of establishing the correct diagnosis is mainly to protect the patient from the chemotherapeutic treatment of polycythemia. Family members should be advised that their children may be affected. The life expectancy of affected individuals is essentially normal, and most patients are symptom free. However, if such patients become symptomatic and their hematocrit rises towards 60%, then phlebotomy may be necessary to reduce blood viscosity.”

Structure - Function Relations of Human Hemoglobin

Link to the Web Article

Oxygen Affinity with Koln

LINK

Hemoglobin Köln Disease Occurring as a Fresh Mutation: Erythrocyte Metabolism and Survival
DENIS R. MILLER 1, ROBERT I. WEED 1, GEORGE STAMATOYANNOPOULOS 1, and AKIRA YOSHIDA 1

1 Department of Pediatrics, Division of Pediatric Hematology, Cornell University Medical College, New York, N.Y., the Departments of Pediatrics and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, N.Y., and the Department of Medicine, Division of Medical Genetics, University of Washington School of Medicine, Seattle, Wash.

Electrophoretic and fingerprinting studies in a patient with congenital hemolytic anemia revealed the presence of the unstable hemoglobin Köln (beta98 valrarrmet). Examination of parents and siblings gave normal results. Extensive blood group and isozyme studies were consistent with the thesis that Hb Köln disease in the propositus was the result of a fresh mutation in one of his parent’s gametes. In the propositus, the activities of enzymes of the Embden-Meyerhof and pentose phosphate pathways were increased, but the level of ATP was decreased. Methemoglobin reduction was delayed when the NADPH-dependent system was utilized with added methylene blue and gave a false-positive result in the glucose-6-phosphate dehydrogenase screening test. Methemoglobin reduction in the absence of methylene blue was normal. Increased methemoglobin and Heinz body formation, decreased osmotic fragility, decreased red cell deformability, and a disproportionate potassium loss without sodium gain occurred with metabolic depletion. The rate of decline of glutathione in propositus’ cells paralleled that in normal cells. Autologous survival of Hb Köln cells was decreased but was not compromised further by oxidant drugs. Marked splenic sequestration of Hb Köln erythrocytes was demonstrated, and an excellent response to splenectomy with improved erythrocyte survival was observed. The intracellular precipitation of unstable globin chains, intracellular dehydration, and increased membrane rigidity probably all contribute to the splenic entrapment of these erythrocytes.

Click HERE for Link

Comparison of hemoglobin Koln erythrocyte membranes with malondialdehyde-reacted normal erythrocyte membranes

DW Allen, CF Burgoyne, JD Groat, CM Smith and JG White

Splenectomized patients with hemoglobin (Hb) Koln have rigid RBCs with membrane polypeptide aggregates that are not dissociable with disulfide- reducing agents. Malondialdehyde (MDA) action on normal RBCs produced rigid RBCs with similar nondissociable aggregates. To test the hypothesis that Hb Koln RBC aggregates contained unsaturated MDA-type bonds, we reduced normal control RBC membranes, Hb Koln RBC membranes, and MDA-reacted membranes with [3H]NaBH4. Hb Koln RBC membranes and MDA- reacted membranes both had significantly more 3H incorporation than control membranes. Furthermore, 3H incorporation in both Hb Koln and MDA-treated membranes was located in the membrane polypeptide aggregates, presumably saturating the crosslinking bonds. After reaction of RBCs with [14C]MDA, the MDA label was similarly concentrated in the membrane polypeptide aggregates. Normal RBC membranes incubated with MDA were analyzed with and without reduction by NaBH4 prior to amino acid determination by high-performance liquid chromatography (HPLC). Reduction with NaBH4 after MDA treatment decreased the lysyl residues by 33% and the serine by 7% and increased by 10% the methionyl residues, but did not affect 12 other amino acids. Similar changes could be detected in NaBH4-reduced Hb Koln aggregates in methionine and serine content. MDA may also alter protein configuration, as evidenced by an increase in the protease susceptibility of membrane proteins from MDA-treated and Hb Koln RBCs. We conclude that Hb Koln RBC membranes, like MDA-treated membranes, have similar high molecular weight aggregates conferring decreased membrane deformability, [3H]NaBH4-reducible unsaturated bonds, changes in amino acid composition upon reduction, and protease-sensitive configurational changes.

Hemoglobin Koln erythrocyte membranes

Hemoglobin Koln occurring in association with a beta zero thalassemia: hematologic and functional consequences

F Galacteros, D Loukopoulos, P Fessas, J Kister, N Arous, B Bohn, A Loutradi, G Tsitrakis and C Poyart

INSERM U 91, Hopital Henri-Mondor, Creteil, France.

Hemoglobin (Hb) Koln-beta zero thalassemia compound heterozygosity was discovered in a young Greek patient. This gave us the unique opportunity for studying the functional properties of this unstable high-oxygen affinity hemoglobin variant in red cells containing almost pure Hb Koln. The red cells of the proposita exhibit morphological alterations and hematologic indices corresponding to the presence of an unstable Hb and beta thalassemia. Globin chain synthesis confirmed the association with a beta zero thalassemia gene. Oxygen-binding curves for these cells were biphasic, indicating the presence of both heme- saturated and of approximately 20% of non-cooperative Hb Koln. The major component exhibits an increased oxygen affinity, reduced cooperativeness, and normal alkaline Bohr effect. The 35-year-old proposita is active, has not been splenectomized, and has not been transfused in several years.

File: Beta Zero Thassalemia

LINK to Web Article

We report a case of severe priapism occurring in a patient with unstable hemoglobin, hemoglobin Köln, and underline several factors that may have contributed to this complication: abnormal plasticity of red cells, splenectomy, and cytomegalovirus Infection. Since emergency treatment may prevent impotence, patients and parents should be educated about this complication.

Read the article HERE

The history of Köln’s hemoglobin starts with a small notification delivered at a Hemoglobin Colloquium in Vienna. Pribilla (1962) reported that an abnormal hemoglobin component had been found on a family from middle Reno, which suffered from a condition similar to thalassemia. They did not have family relations with Mediterranean, African or Asian people. This component, which in electrophoresis formed a smaller band between hemoglobin A and hemoglobin A₂, and which comprised about 5% of total hemoglobin, appeared as a “new” hemoglobin and was called Köln’s hemoglobin. A more detailed description of the case in this family was given by Pribilla and colleagues (1965) with the title Hämoglobin-Köln-Krankheit: familiäre hupocrome hämolytische anämie mit hämoglobinamalie. Of the nine cases found in four generations, five were confirmed and four remained inconclusive. The patients were moderately anemic: hemoglobin 10.5-13.5g/dl, reticulocytes 190-270 x 10⁹/l, MCH 26-28pg, MCV 96-122fl, bilirubin 1.0-2.5mg/dl; there were anisocytosis and basophilic dots. The osmotic fragility were moderately reduced. All had splenomegaly. Physico-chemical studies led to the conclusion that the abnormal hemoglobin was characterized as an abnormality in its b-globin chain between residues 83 and 120. It was later demonstrated by Carrell, Lehmann and Pribilla (1967), in Cambridge, that the German Köln’s hemoglobin had the same abnormality (methionine instead of valine in position b 98) as had been previously found in two families in Great Britain (1).

the term unstable hemoglobins must only be used for those hemoglobins that produce Heinz inclusion bodies in patients with acute or chronic hemolytic anemia

Read the entire article HERE