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Hemoglobinopathy
Hematology and Coagulation
| True hemoglobinopathies | Abnormalities in the gene to produce the globin chains in hemoglobin and the defect is structural |
| Thallasemia | Both the alpha and beta chains are structurally normal. The defect is quantitative! |
| Disease | Manifestation of hemolytic condition. Homozygous or heterozygous dominant gene |
| Trait | Heterozygous and it has asymptomatic state |
| Sickle Cell Disease - Major Defect | Abnormal Hgb structure and function. A gene is inherited from one of the parents. Forms Hgb S |
| Sickle Cell Disease - Cause of defect | Substitution of valine for glutamic acid in the 6th position of the beta chain of the Hgb |
| Sickling occurs under | Low O2, low pH, increased 2,3DPG, low cell water, presence of Hgb C |
| Clinical Manifestations - Sickle Cell Disease | Painful, vascular occlusion, enlarged heart, stroke, arthritis, liver damage. |
| Lab Findings of Sickle Cell Disease | Decreased Hgb, decreased Hct and RBC |
| RBC morphology seen in Sickle Cell Disease | Moderate-significant poik, aniso and hypo. Microcytes, polychromatophilia, Basophilic stippling, Sickle cells, target cell, Howell Jolly Bodies |
| Sickle Cell Trait | Heterozygous for Beta HbS. Presence of HbS&A |
| Sickle Cell Traits can be detected on Elecrophoresis with the following results | 35-45% HbS. 55-65% HbA |
| Hemoglobin C Disease | Substitution of lysine for glutamic acid in the sixth position of the beta chain of HbA |
| Clinical Manifestation of HbC Disease | Decreased solubility.Forms crystals |
| Lab findings in HbC | Normochromic, normocytic > then 50% target cells, Mild hypochromasis |
| Hemoglobin SC Disease | Absence of HbA. Normal to increased HbF |
| Hb-SC Disease - Clinical Manifestation | Mild-moderate normocytic, normochromic hemolytic anemia. |
| Lab Finding of Hb-SC | 50% Target cells, Folded RBCs, Intracellular crystals, no sickle cells |
| Hemoglobin D Disease | Homozygous and heterozygous are asymptomatic |
| Lab findings in HbD Disease | Target cells |
| Electrophoresis of HbD Disease | In alkaline pH-HbD migrates with HbS+HbG. In acid pH-HbD migrates with HbA |
| Hemoglobin E Disease | Results from the substitution of lysine for glutamic acid in the 26th position on the beta globin chain |
| Clinical Manifestations of HbE Disease | Worldwide second most common abnormal hemoglobin. In US are discovered through prenatal testing of high risk populations |
| Thalassemia | The rate of synthesis of alpha or beta globin chains is decreased. Leads to an imbalance of globin chains available for hemoglobin dimer construction |
| Beta-Thalassemia | Most common. Single-gene disorder - Defect on chromosome 11 |
| Clinical Manifestation in Beta-Thalassemia | Decreased production of beta chain. Ineffective erythropoiesis. Shortened red cell survival |
| Thalassemia minor | ß+ chains are made in mildly reduced amounts |
| Thalassemia major | No ß chains (ßo) or very little is made (ß+) |
| Lab Findings in Thalassemia Major | Decreased Hgb, Hct, and RBCs,Anisocytosis & poikilocytosis. Polychromasia, microcytic, hypochromic.Target cells. Few nucleated RBCs. Increased reticulocytes. Decrease osmotic fragility. Increased Bilirubin, increased Iron |
| Alpha Thalassemia | Results from deletions that remove one or both alpha globin genes from chromosome 16 |
| Silent carrier state | One inactive alpha gene |
| Alpha Thalassemia trait | Two inactive genes. Imbalance of alpha and beta chains causes an excess of beta chains |
| Hemoglobin H disease | Three inactive genes. Tetrad of beta chains form |
| Lab Findings in HbH | Moderately-severe hemolytic anemia. Hgb 8-10 g/dl. Reticulocyte 5-10%. 4-30% Hgb H on electrophoresis |
| Hydrops fetalis with Hb Bart’s | Four inactive genes. Makes Gamma chains. Produces Gamma tetrads. Incompatible with life- fetus dies in utero or shortly after birth |
| Hemoglobin Constant Spring | Unusual form of silent carrier. Hemoglobin is formed from the combination of two structurally abnormal alpha chains |
| Sickle-beta Thalassemia | Sickle gene from one parent. B-Thalassemia gene from the other |
| Clinical manifestations of Sickle-Beta Thalassemia | Splenomegaly - 70% of the cases. Most severe manifestation in patients who cannot produce any HbA |
| Lab Finding of Sickle-Beta Thalassemia | Hypochromasia, Microcytosis with polychromasia. Target cells. Basophilic stippling |
| Methemoglobinemia | Elevated levels of methemoglobin in circulating blood |
| Hereditary Persistance of Fetal Hemoglobin | Persistance of HbF in adults. 15-30% of the total hemoglobin |
Created by:
liudka11
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