Thalassemia Flashcards
Define Thalassemia
Decreased production of one or more globin chains
Which chains are in the Alpha Family category
Alpha and Zeta chains
Which chains are in the Beta Family category
Beta, Delta, Gamma, and Epsilon chains
What are the normal adult hemoglobin and their compositions?
Hgb A (α2β2)
Hgb A2 (α2δ2)
Hgb F (α2γ2)
Which Hemoglobin type is affected by β-Thalassemia?
Hgb A (α2β2)
What are the two effects seen in β-Thalassemias?
Total Hgb reduced, more Hgb A2 and F produced to compensate.
Accumulation of free α-chains.
Which Thalassemia has precipitation of free chains leading to destruction within the bone marrow?
β-Thalassemia Major, resulting in free α-chains precipitation and destruction in the bone marrow, and bone marrow expansion.
What are the 4 types of α-Thalassemia?
Silent Carrier (-α/αα)
Heterozygous (–/αα) or (-α/-α)
Hemoglobin H Disease (–/-α)
Hydrops Fetalis (–/–)
Gamma 4 tetramers are called what?
Hgb Barts (γ4)
Beta 4 tetramers are known as what?
Hgb H (β4)
Which α-Thal is clinically and appears similar to β-Thal Minor?
α-Thal Minor - Mild microcytic hypochromic anemia
Which α-Thal is clinically similar to β-Thal Major (though generally tends to be milder)?
Hemoglobin H disease (–/-α)
Which α-Thal is incompatible with life?
Hydrops Fetalis (–/–)
What do Hemoglobin H inclusions look like in a supravital stain?
Golf Balls!
How are Hgb Barts tetramers unique?
Extremely high affinity for O2 and will not release in fetal tissue, leads to tissue hypoxia and death.
How is α-Thal hard to diagnose via Hgb Electrophoresis?
All normal Hgb levels proportionally decreased across the board, mainly ID abnormal Hgbs such as Hgb Barts or Hgb H
How is osmotic fragility affected by Thalassemia?
Decreased osmotic fragility
How is Hgb Electrophoresis critical to the diagnosis of β-Thal?
Diagnosed via decreased Hgb A and increased Hgb A2 and/or Hgb F
