Metabolism USMLE Step 1 Practice Question
A 3-week-old female infant (46,XX) presents with ambiguous genitalia, poor feeding, and lethargy. Vital signs show BP 78/52 mmHg, HR 148/min, RR 32/min, temp 36.8°C. Laboratory studies reveal serum potassium 6.8 mEq/L, sodium 128 mEq/L, and elevated 17-hydroxyprogesterone. Abdominal ultrasound shows normal adrenal glands without hemorrhage. 21-hydroxylase deficiency is confirmed. The adrenal steroid hormones that cannot be synthesized in this patient normally bind to receptors with which of the following characteristics?
Answer choices
- ATyrosine kinase activity
- BHelix-loop-helix motif with dyad symmetry
- CSeven transmembrane helices
- DGuanylate cyclase activity
- EZinc finger motifCorrect answer
- FLeucine zipper motif
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