Thalassemias: Genetic Disorders of Hemoglobin
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Questions and Answers

What percentage of Hemoglobin S (Hb S) would result in a positive solubility screening test?

  • 30%
  • 40%
  • 20% (correct)
  • 10%

    • Which hemoglobin types and percentages are typically shown in hemoglobin electrophoresis for someone with Hb S?

  • Hb A = 60%, Hb S = 40% (correct)
  • Hb A = 70%, Hb S = 30%
  • Hb A = 80%, Hb S = 20%
  • Hb A = 50%, Hb S = 50%

    • When are sickle cells typically seen in a peripheral blood smear?

  • During sickle cell crises (correct)
  • Never present
  • Only when there is severe dehydration
  • Always present in individuals with sickle cell trait

    • What amino acid replaces glutamic acid at the 6th position of the β chain in Hemoglobin C disease?

    <p>Lysine</p> Signup and view all the answers

    Which statement is true regarding hemoglobin electrophoresis of Hemoglobin C (Hb C) at alkaline pH?

    <p>Hb C migrates with Hb A₂</p> Signup and view all the answers

    What is the primary cause of alpha thalassemia?

    <p>Gene deletion</p> Signup and view all the answers

    Which type of thalassemia results from a defect in the rate of synthesis of beta chains?

    <p>Beta thalassemia</p> Signup and view all the answers

    How many genes are involved in making the alpha hemoglobin chain?

    <p>4</p> Signup and view all the answers

    Which thalassemia condition is also known as Cooley Anemia?

    <p>Beta Thalassemia Major</p> Signup and view all the answers

    Where is the gene for the beta chain located?

    <p>Chromosome 11</p> Signup and view all the answers

    What typically causes Beta Thalassemia?

    <p>Point mutation</p> Signup and view all the answers

    Why doesn't beta thalassemia manifest at birth?

    <p>Presence of predominant Hb F</p> Signup and view all the answers

    What characterizes the silent carrier state of beta thalassemia?

    <p>Mild mutation</p> Signup and view all the answers

    Which genotype is associated with β thalassemia major?

    <p>βο/βο</p> Signup and view all the answers

    What clinical severity is typically observed in individuals with the genotype β/βο?

    <p>Silent</p> Signup and view all the answers

    In the pedigree chart, which condition does the first child exhibit?

    <p>β thalassemia trait</p> Signup and view all the answers

    Which classification of β thalassemia is associated with moderate anemia?

    <p>β thal intermedia</p> Signup and view all the answers

    What is the expected clinical severity in an individual with the genotype β+/β+?

    <p>Moderate</p> Signup and view all the answers

    What genotype does the mother in the pedigree chart have?

    <p>β β+</p> Signup and view all the answers

    What is the characteristic genotype of a silent carrier of β thalassemia?

    <p>β/β+</p> Signup and view all the answers

    Which child in the pedigree chart does not have any form of anemia?

    <p>Third child</p> Signup and view all the answers

    What kind of anemia is characteristic of Beta-Thalassemia?

    <p>Microcytic, hypochromic anemia</p> Signup and view all the answers

    Which type of cells are most commonly seen in the peripheral blood of Beta-Thalassemia patients?

    <p>Target cells</p> Signup and view all the answers

    What is a common complication of regular transfusions in Beta-Thalassemia patients?

    <p>Iron overload</p> Signup and view all the answers

    Which hemoglobin type is most commonly elevated in Beta-Thalassemia patients?

    <p>Hb F</p> Signup and view all the answers

    What physical features are associated with Beta-Thalassemia?

    <p>Protrusion of upper teeth and mongoloid facial features</p> Signup and view all the answers

    Which of the following is not a hazard of transfusion treatment in Beta-Thalassemia?

    <p>Hyperproliferation of erythrocytes</p> Signup and view all the answers

    What is the predominant cause of alpha thalassemia?

    <p>Alpha globin chain gene deletion</p> Signup and view all the answers

    How many alpha globin chain genes are located on chromosome 11?

    <p>4</p> Signup and view all the answers

    What condition results from the presence of only one functional alpha globin gene?

    <p>Hemoglobin H disease</p> Signup and view all the answers

    Which clinical condition corresponds to the genotype aa/--?

    <p>Alpha thalassemia trait</p> Signup and view all the answers

    What results from the absence of alpha chains during fetal life?

    <p>Increase in gamma chains</p> Signup and view all the answers

    Which genotype corresponds to Bart's hydrops fetalis syndrome?

    <p><em>--/--</em></p> Signup and view all the answers

    What is a key characteristic of Beta-thalassemia?

    <p>Less hemoglobin is made resulting in too few red blood cells</p> Signup and view all the answers

    Which of the following is NOT a lifestyle tip for managing thalassemia?

    <p>Engage in strenuous physical exercise</p> Signup and view all the answers

    Which type of red blood cells are affected in Sickle Cell Disease?

    <p>Stiff and misshapen red blood cells</p> Signup and view all the answers

    When is World Thalassemia Day celebrated?

    <p>8th May</p> Signup and view all the answers

    Which disorder involves a gene deletion affecting only delta and beta genes?

    <p>Delta Beta Thalassemia</p> Signup and view all the answers

    What is the hemoglobin type predominantly found in homozygous cases of Delta Beta Thalassemia?

    <p>Hb F</p> Signup and view all the answers

    Which condition is characterized by a gene deletion causing hemoglobinopathy and Bart's hydrops fetalis?

    <p>Hemoglobin Lepore</p> Signup and view all the answers

    Which type of thalassemia results from the presence of two altered HBB genes?

    <p>Sickle Cell</p> Signup and view all the answers

    What physical examination finding indicates hemolysis in thalassemia patients?

    <p>Jaundice</p> Signup and view all the answers

    Which of the following is a common symptom of thalassemia?

    <p>Dark urine</p> Signup and view all the answers

    Which parameter differentiates thalassemia from iron deficiency anemia in carrier states?

    <p>Elevated RBC count with decreased MCV, normal RDW</p> Signup and view all the answers

    What does a PB stained smear typically show in thalassemia major?

    <p>Many target cells and basophilic stippling</p> Signup and view all the answers

    What is a key clinical feature of beta thalassemia major?

    <p>Skeletal deformity</p> Signup and view all the answers

    Which lab finding is typical in thalassemia minor or trait?

    <p>Normal to slightly decreased MCHC</p> Signup and view all the answers

    What happens when brilliant cresyl blue stain is used for a prolonged period?

    <p>Hb H precipitates</p> Signup and view all the answers

    Which staining method is based on the Kleihauer-Betke procedure?

    <p>Acid elution stain</p> Signup and view all the answers

    Which of these conditions is diagnosed with the presence of only one gene producing alpha chains?

    <p>Hemoglobin H Disease</p> Signup and view all the answers

    What is a characteristic feature of the silent carrier state for β thalassemia?

    <p>Only a small decrease in production of beta chains</p> Signup and view all the answers

    Which condition results in a baby born with hydrops fetalis?

    <p>Bart's Hydrops Fetalis Syndrome</p> Signup and view all the answers

    Which of the following hemoglobins remains in cells when subjected to acid elution staining?

    <p>Hb F</p> Signup and view all the answers

    What is the typical hemoglobin range observed in individuals with beta thalassemia minor?

    <p>10-13 g/dL</p> Signup and view all the answers

    Which of the following is characterized by mild microcytic, hypochromic anemia?

    <p>Alpha Thalassemia Trait</p> Signup and view all the answers

    Which feature is useful for differentiating HPFH from beta thalassemia?

    <p>Acid elution stain</p> Signup and view all the answers

    Which characteristic appearance do RBCs exhibit in Hb H disease when stained with brilliant cresyl blue?

    <p>Golf ball appearance</p> Signup and view all the answers

    What is the typical hemoglobin composition for an adult with Hemoglobin H Disease?

    <p>10-20% Hemoglobin H (beta4)</p> Signup and view all the answers

    Which type of beta thalassemia can occur with either heterozygous or homozygous mutations?

    <p>Beta thalassemia intermedia</p> Signup and view all the answers

    Which condition is the most severe form of alpha thalassemia and is incompatible with life?

    <p>Bart's Hydrops Fetalis Syndrome</p> Signup and view all the answers

    Which diagnostic method is used to differentiate various forms of thalassemia and hemoglobinopathies?

    <p>Hemoglobin electrophoresis</p> Signup and view all the answers

    Which hemoglobin types are increased in beta thalassemia intermedia?

    <p>Hb A2 and Hb F</p> Signup and view all the answers

    Which of the following is NOT typically seen in a peripheral blood smear of someone with thalassemia major?

    <p>High RBC count</p> Signup and view all the answers

    Which clinical condition is related to the observation of marked bone changes due to expansion of marrow space?

    <p>Beta thalassemia major</p> Signup and view all the answers

    In which condition are there usually no hematologic abnormalities and the diagnosis requires genetic mapping?

    <p>Silent Carrier State</p> Signup and view all the answers

    What is a common differential diagnosis for beta thalassemia minor?

    <p>Iron deficiency anemia</p> Signup and view all the answers

    Which beta thalassemia type typically requires transfusions only under stress conditions like pregnancy or infection?

    <p>Beta thalassemia intermedia</p> Signup and view all the answers

    What differentiates Alpha Thalassemia Trait from iron deficiency anemia?

    <p>Low MCV and elevated RBC count</p> Signup and view all the answers

    Which of the following is a common presentation in infants with beta thalassemia major?

    <p>Failure to thrive and pallor</p> Signup and view all the answers

    Study Notes

    Thalassemias

    • Diverse group of disorders that manifest as anemia of varying degrees
    • Result in defective production of globin chain of Hb molecule
    • Distribution is worldwide
    • May be either homozygous defect or heterozygous defect
    • Globin chains are structurally normal, but have imbalance in production of the two types of globin chains
    • Results in overall decrease in amount of Hb produced and may induce hemolysis

    Types of Thalassemias

    • Alpha (α) thalassemia: caused by defect in rate of synthesis of alpha chains
    • Beta (β) thalassemia: caused by defect in rate of synthesis of beta chains

    Genetics of Thalassemia

    • Adult hemoglobin is composed of two alpha and two beta chains
    • Alpha thalassemia usually caused by gene deletion; Beta thalassemia usually caused by point mutation

    Alpha Thalassemia

    • 4 genes are involved in making the alpha hemoglobin chain
    • Classification of alpha thalassemia:
      • Silent carrier state: deletion of one alpha gene
      • Alpha thalassemia trait: deletion of two alpha genes
      • Hemoglobin H disease: deletion of three alpha genes
      • Bart's hydrops fetalis syndrome: deletion of four alpha genes

    Beta Thalassemia

    • 2 genes are involved in making the beta hemoglobin chain
    • Classification of beta thalassemia:
      • Beta thal minor/trait: heterozygous genotype
      • Beta thal intermedia: homozygous genotype
      • Beta thal major: homozygous genotype with two mutated beta-globin genes

    Characteristics of Beta Thalassemia

    • Severe microcytic, hypochromic anemia
    • Peripheral blood smear shows:
      • Markedly hypochromic, microcytic erythrocytes
      • Extreme poikilocytosis
      • Target cells, teardrop cells, and elliptocytes
      • Basophilic stippling and numerous NRBCs
    • High reticulocyte count (2-8%)
    • Most of hemoglobin present is Hb F with or without slight increase in HbA2

    Complications of Beta Thalassemia

    • Excessive number of transfusions results in iron overload and hemosiderosis
    • Without iron chelation, patients develop cardiac disease

    Treatment of Beta Thalassemia

    • Transfusion is the main line of treatment
    • Carries the following hazards:
      • Development of iron overload
      • Development of alloimmunization
      • Risk of transfusion-transmitted diseases

    Lifestyle Tips for Thalassemia

    • Avoid excessive iron
    • Eat a healthy diet
    • Avoid infections
    • Get annual flu shots and Hepatitis B vaccines

    Other Defects in the Beta-Cluster Gene

    • Delta Beta Thalassemia
    • Hemoglobin Lepore
    • Hereditary Persistence of Fetal Hemoglobin (HPFH)

    Delta Beta Thalassemia

    • Group of disorders due to gene deletion that removes or inactivates only delta and beta genes
    • Clinically similar to beta thalassemia minor when heterozygous and beta thalassemia intermedia when homozygous

    Hemoglobin Lepore

    • Rare class of thalassemia caused by a gene deletion in a beta locus on the chromosome
    • Characterized by a silent carrier, alpha thalassemia, hemoglobinopathy, and Bart's hydrops fetalis

    World Thalassemia Day

    • Celebrated on May 8th

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    Description

    Learn about thalassemias, a group of genetic disorders that affect the production of hemoglobin, leading to anemia and other complications. Understand the causes, types, and characteristics of thalassemias.

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