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Hemoglobinopathies
UMDNJSOM
| Question | Answer |
|---|---|
| What are the three types of hemoglobin | HbA(a2b2), HbF(a2y2), HBA2(A2D2) |
| Zeta globin and Epsilon Globin | Only prenatal. |
| Hemoglobinopathies | Genetic defect that results in abnormal structure of one of the globin chains of the hemoglobin molecule. |
| Thalassemia | Genetic defect that results in production of an abnormally low or zero quantity of a given hemoglobin chain or chains |
| Beta^o thalassemia, Cooley's anemia, thalassemia major | no production of Beta Chain. Only produce HBA2(a2D2) and HBF(a2y2) and unstable a4 tetramers |
| B+ thalassemia, Thalassemia minor | only one copy of normal beta globin gene. carries genetic trait for thalassemia, usually experience no help problems other than mild anemia. |
| Why is beta thalassemia dangerous? | Body cant make enough B chains, compensates by making more delta chains.Some of the excessive a chains used to make HbA2.Remaining a chains precipitate in cells, reacting with membrane,intervening with cell divison,act as foreign bodies,destruction of RBC |
| Alpha Thalassemia | Hb Bart Syndrome is the more severe type. HbH is the milder form. |
| Hemoglobin Bart hydrops fetalis | no alpha globin. inactivation of all four alpha globin chains. these fetuses have Hb barts (y4) primarily. Cant deliver o2 to tissues, unstable. Severely anemic. All fetuses succumb to severe fetal hypoxia. |
| Hemoglobin H disease | milder form of alpha thalassemia. loss of 3 of the four alpha alleles. results in hemoglobin H, B4. |
| Sickle Cell Disease | mutation in B-globin chain of Hb. Changes 6th AA in B-Chain, from glutamic acid to valine. A to T. HbS. aaBsBs or aaBBs. Valine results in Hb tetramers that aggregate into arrays upon deoxygenation in tissues. |
| What causes irreversible sickling in Sickle Cell Disease | Repeated cycles of oxygenation and deoxygenation. During sickle cell "crisis", often pain in bones because they are affected by reduced blood flow due to clogging of capillaries. |
| Why does HbS sickle? | Valine is hydrophobic. valine-6 is now a sticky patch on outside of Hb. now it interacts with Phe and Leu from another Hb molecule. As fibers form, cause shape of RBC to become sickle shaped. |
| Sickle/Beta Thalassemia | Gene from HbS from one parent, Bthalassemia from other. HbSBo = no normal hemoglobin. same as sickle cell disease. HbSb+ = small amt of Hb normal. called B+ thalassemia. less severe. |
| Malaria + sickle cell | Plasmodium parasite. Sickled cells are sent to spleen and destroyed ASAP, so is parasite in cells. Parasite thrives on Hb. mutated HbS polymerizes, parasite cant ingest Hb. RBC sickle under low O2.Malarial Parasite reduces O2 in RBC by using up O2.Sickles |
| continued from previous card | Also, cell membrane of sickled RBC stretched, becomes porous, leaks nutrients like K+ that parasite needs, so it does. Person with HbS is resistant to malaria. |
| Hemozoin | Digestion of Hb, releases Heme. Free heme, toxic, destabilize+lyse membranes, inhibit enzymes. Turning heme into hemozoin(malarial pigment), detoxifies it. |
| Hemoglobin C | common mutation at codon 6, conversions from glutamic acid to lysine in B globin gene. REsults in HbC. miild hemolytic anemia. unstable Hb forms crystals. decrease RBC deformity, increase viscosity. spleen removes them. Impairs malaria growth+development |
Created by:
nady
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