Alpha thalassemia vs Beta thalassemia
How to tell Alpha thalassemia and Beta thalassemia apart when a board question makes them look alike.
Alpha is gene deletion with often normal electrophoresis in trait; beta is point mutation with increased HbA2 in trait and severe disease after infancy.
Side by side
Alpha-globin gene deletions on chromosome 16 with severity by number of deleted genes, normal electrophoresis in trait, HbH with three deletions, and hydrops with four deletions.
Beta-globin point mutations on chromosome 11 with beta-thal minor or major, elevated HbA2 in minor, severe anemia after infancy in major, and marrow expansion.
Deleted alpha genes reduce alpha-chain production, affecting fetal and adult hemoglobin because alpha chains are needed throughout life.
Beta-chain synthesis is reduced or absent, causing excess alpha chains and ineffective erythropoiesis after HbF declines.
Microcytosis with normal iron and often normal electrophoresis in alpha trait; HbH or Hb Bart patterns appear in severe deletion states.
Elevated HbA2 supports beta-thalassemia trait; severe beta major has high HbF, target cells, and marrow expansion.
The trap
Both are microcytic with normal iron, so genetics and electrophoresis timing separate them.
Watch it explained
The repair move
For thalassemia, ask whether electrophoresis is normal alpha trait or HbA2-high beta trait.
Try a free question
CoreA patient has lifelong microcytosis, normal iron studies, normal hemoglobin electrophoresis, and family members with mild anemia. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Alpha thalassemia trait. Microcytosis with normal iron and normal electrophoresis is a classic alpha thalassemia trait pattern.
Why the other choices are tempting
- B. Beta thalassemia trait usually increases HbA2 on electrophoresis.
- C. Iron deficiency has low ferritin and high TIBC.
- D. Sideroblastic anemia has ring sideroblasts and increased iron stores.
- E. Lead poisoning has exposure clues and basophilic stippling.
Flashcards
Tap a card to flip it.
What genetic mechanism points to alpha thalassemia?
Alpha-globin gene deletions point to alpha thalassemia.
What electrophoresis clue points to beta thalassemia trait?
Elevated HbA2 points to beta thalassemia trait.
Quick answers
What is the fastest way to tell Alpha thalassemia from Beta thalassemia?
Alpha is gene deletion with often normal electrophoresis in trait; beta is point mutation with increased HbA2 in trait and severe disease after infancy.
What is the key clue for Alpha thalassemia?
Alpha-globin gene deletions on chromosome 16 with severity by number of deleted genes, normal electrophoresis in trait, HbH with three deletions, and hydrops with four deletions.
What is the key clue for Beta thalassemia?
Beta-globin point mutations on chromosome 11 with beta-thal minor or major, elevated HbA2 in minor, severe anemia after infancy in major, and marrow expansion.
What is the common trap with Alpha thalassemia vs Beta thalassemia?
Both are microcytic with normal iron, so genetics and electrophoresis timing separate them.