A 35-year-old woman presents with crushing substernal chest pain and shortness of breath. A coronary artery is occluded due to an atherosclerotic plaque, and she is diagnosed with having a myocardial infarction. Her serum cholesterol level is 700 mg/dL. She has a family history of hypercholesterolemia. Which of the following is the inherited defect in individuals with familial hypercholesterolemia?
A) abnormal LDL receptors
B) high activity of HMG-CoA reductase
C) increased conversion of VLDL to LDL
D) low activity of 7-a hydroxylase
E) reduced plasma concentration of HDL

Question

A 35-year-old woman presents with crushing substernal chest pain and shortness of breath. A coronary artery is occluded due to an atherosclerotic plaque, and she is diagnosed with having a myocardial infarction. Her serum cholesterol level is 700 mg/dL. She has a family history of hypercholesterolemia. Which of the following is the inherited defect in individuals with familial hypercholesterolemia?
A) abnormal LDL receptors
B) high activity of HMG-CoA reductase
C) increased conversion of VLDL to LDL
D) low activity of 7-a hydroxylase
E) reduced plasma concentration of HDL

Quizplus · Accepted Answer

Familial hypercholesterolemia is caused by a genetic defect in the LDL receptor, leading to decreased clearance of LDL from the bloodstream and resulting in high cholesterol levels.  Familial hypercholesterolemia, FH (type II hyperlipoproteinemia), is an autosomal dominant disorder that results from mutations affecting the structure and function of the cell-surface receptor that binds plasma LDLs, removing them from the circulation. The defects in LDL-receptor (LDLR) interaction result in lifelong elevation of LDL-cholesterol in the blood. The resultant hypercholesterolemia leads to premature coronary artery disease and atherosclerotic plaque formation.

A 35-Year-Old Woman Presents with Crushing Substernal Chest Pain and Shortness