A 14-Year-Old Boy Is Brought to the Emergency Department After

question 75

Multiple Choice

A 14-year-old boy is brought to the emergency department after accidental ingestion of a chicken bone that lodged in his esophagus.  Upper endoscopy is performed and the bone is successfully removed.  However, the patient is incidentally found to have mild hypercalcemia on laboratory testing.  On follow-up with his primary care provider 2 weeks later, he has no symptoms and clinical examination is unremarkable.  Further questioning reveals that several of his family members also have mild hypercalcemia.  Subsequent laboratory studies show a borderline high parathyroid hormone concentration, very low urinary calcium level, and normal 25-hydroxyvitamin D level.  A mutation in which of the following receptors is most likely responsible for this patient's laboratory abnormalities?

• A)Intracellular receptor with a DNA-binding domain
• B)Membrane-bound receptor coupled with a G protein
• C)Transmembrane ligand-gated ion channel
• D)Transmembrane receptor associated with intrinsic tyrosine kinase activity
• E)Transmembrane receptor causing activation of Janus kinase/STAT pathway

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