Welcome to MedSmarter’s USMLE Style Question Break Down of the Week. For those preparing for the USMLE Step 1, this week we break down a high-yield Biochemistry question. As always you want to begin with reading the last sentence of the vignette first to get an understanding of what the question is asking for.
Question Break Down of the Week:
A 40-year-old woman presents to a new physician because of the recent onset of fatigue, arthralgias, discomfort in her right upper quadrant, and polyuria. On physical examination, her skin seems somewhat browner than would be expected. Laboratory tests are remarkable for an elevated glucose level, indications of hemolysis, and increased transferrin saturation. Cardiac testing shows moderate restrictive cardiomyopathy. She mentions that she regularly requires blood transfusions. Which of the following is the cause of this patient’s condition?
A) Mutations resulting in copper accumulation
B) Absence of the hemoglobin α chain
C) Mutation of the hemoglobin β chain
D) Mutation resulting in increased absorption of dietary iron
E) Mutations in the gene encoding ankyrin
The correct answer choice is C: This woman suffers from β-thalassemia major. Clinically, β-thalassemia major manifests as severe hemolysis and ineffective erythropoiesis. These individuals are transfusion-dependent and frequently develop iron overload. The consequences of iron overload due to transfusion dependency or secondary hemochromatosis are described in the question stem. These manifestations are due to iron deposition in various tissues, including the pancreas, heart, and skin.
Did you think the answer was different?
Did you think that the correct answer choice was other than B? You can view this video for a deeper discussion of why A, C, D, and E are not the correct answer choices.
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