This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
[{'content': 'A 25-year-old man requests cholesterol screening because of a family history of premature coronary artery disease (CAD). His lipid levels reveal an elevated total and LDL cholesterol. The high-density lipoprotein (HDL) and triglyceride values are normal. His physical examination is completely normal. Which of the following is the most common cause of genetic dyslipidemia? \nSelect and explain. \nA. familial combined hyperlipidemia, B. familial hypercholesterolemia, C. familial defective Apo B, D. Apo C-II deficiency', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Familial combined hyperlipidemia has an incidence of 1/100. It is an autosomal dominant disorder and different affected family members may display different dyslipidemic phenotypes. Familial hypercholesterolemia (1/500) and familial defective Apo B (1/1000) are also common. The other two disorders (Apo C-II deficiency and lipoprotein lipase deficiency) are extremely rare.', 'role': 'assistant'}]