A Physician Is Providing Care for a Number of Patients

A physician is providing care for a number of patients on a medical unit of a large, university hospital. The physician is discussing with a colleague the differentiation between diseases that are caused by abnormal molecules and diseases that cause disease. Which of the following patients most clearly demonstrates the consequences of molecules that cause disease?

A) A 31-year-old woman with sickle cell anemia who is receiving a transfusion of packed red blood cells
B) A 91-year-old woman who has experienced an ischemic stroke resulting from familial hypercholesterolemia
C) A 19-year-old man with exacerbation of his cystic fibrosis requiring oxygen therapy and chest physiotherapy
D) A 30-year-old homeless man who has Pneumocystis carinii pneumonia (PCP) and is HIV positive.