Hemoglobin

Hemoglobinopathy

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Hemoglobinopathy, Hemoglobin Disorder

  • See Also
  1. Red Blood Cell Physiology
  2. Hemoglobin Production
  • Physiology
  1. See Red Blood Cell Physiology
  2. Normal Hemoglobin is composed of 4 Protein-Heme complexes
    1. Two pairs of polypeptides (4 total)
      1. A pair of alpha chains are found in every normal Hemoglobin type
      2. A pair of other identical polypetides depending on Hemoglobin type (Gamma, Beta, Delta)
    2. Central iron-containing heme ring
      1. Attached to each of the 4 polypeptides
    3. Images
      1. hemoglobin.jpg
  3. Six types of normal Hemoglobin
    1. Embryonic
    2. Gower I
    3. Gower II
    4. Portland
    5. Fetal Hemoglobin (HbF): Alpha2-Gamma2
      1. Primary Hemoglobin in fetus
      2. Replaced by Adult Hemoglobin by age 6-12 months
    6. Adult Hemoglobin (HbA): Alpha2-Beta2
    7. Adult Hemoglobin (HbA2): Alpha2-Delta2
  4. Thalassemia related Hemoglobins
    1. Hemoglobin Bart's: Gamma4
      1. Seen in Alpha Thalassemia
    2. Hemoglobin H: Beta4
      1. Seen in Beta Thalassemia
  • Types
  • Sickle Cell Syndromes
  1. Sickle Cell Disease
    1. Sickle Cell Trait
    2. Sickle Cell Anemia
    3. Combination disorders
      1. Sickle B Thalassemia
      2. Sickle C Disease (SC)
      3. Sickle D Disease (SD)
  2. Sickle Cell Related Hemoglobin (Hb S)
    1. Hemoglobin S (Hb S) replaces the normal Hemoglobin A
      1. Deoxygenated Hemoglobin-S assumes a sickle shape deforming Red Blood Cells
      2. Deoxygenated HbS aggregates under low oxygen tension
        1. Molecules polymerize into a gelatinous network
        2. Deforms Red Blood Cells into a sickle shape
      3. Red cells with sickle shape are less deformable
        1. Results in microvascular Occlusion, ischemia and acidosis from sludging within arterioles
        2. Results in Hemolysis due to red cell fragility
    2. Chromosome 11 Mutation: Substitution of Amino AcidValine for Glutamic Acid
      1. Occurs at the 6th position of the Hemoglobin beta-chain
      2. Results in a "sticky" Hemoglobin that forms a rigid chain when deoxygenated
      3. Sickle cell gene is inherited in Autosomal Recessive pattern
        1. Heterozygotes have Sickle Cell Trait and Homozygotes have Sickle Cell Anemia
        2. Sickle Cell Trait is protective against Malaria, resulting in up to 40% trait Prevalence in some African regions
  1. Alpha Thalassemia (Hemoglobin Bart's: Gamma4)
  2. Beta Thalassemia (Hemoglobin H: Beta4)
    1. Beta Thalassemia minor
    2. Beta Thalassemia Major
  1. Congenital Heinz body Hemolytic Anemia
  2. Methemoglobinemia