Anemias USMLE Step 1 Practice Question
A 9 month old boy of Mediterranean ancestry is brought for poor feeding and failure to thrive. Examination shows pallor, jaundice, and frontal bossing. Laboratory studies reveal severe microcytic anemia. Peripheral smear shows target cells, and hemoglobin electrophoresis shows markedly increased hemoglobin F with absent hemoglobin A. Which of the following is the most likely underlying defect?
Answer choices
- AAutoantibodies against red blood cell surface proteins
- BDeletion of all 4 alpha globin genes
- CPoint mutation causing reduced beta globin synthesisCorrect answer
- DDefective spectrin anchoring to the red cell membrane
- ESubstitution of valine for glutamate at position 6 of beta globin
- FDeletion of the beta globin gene with compensatory increase in gamma globin expression
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