Fredrickson&;s type II hyperlipoproteinemia is due to excess amount of
**Core Concept**
Fredrickson's type II hyperlipoproteinemia is a genetic disorder characterized by an excess of low-density lipoprotein (LDL) cholesterol in the blood, leading to premature atherosclerotic cardiovascular disease. This condition is often associated with mutations in the LDL receptor gene, resulting in impaired clearance of LDL cholesterol from the bloodstream.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of Fredrickson's type II hyperlipoproteinemia. The condition is caused by a deficiency of functional LDL receptors on the surface of hepatocytes, which are responsible for removing LDL cholesterol from the blood. This deficiency leads to an accumulation of LDL cholesterol in the bloodstream, resulting in hypercholesterolemia. The impaired clearance of LDL cholesterol is due to mutations in the LDL receptor gene, which reduces the number of functional LDL receptors on the surface of hepatocytes.
**Why Each Wrong Option is Incorrect**
**Option A:** Apolipoprotein A-I is the primary protein component of high-density lipoprotein (HDL) cholesterol, which is involved in reverse cholesterol transport. It is not directly associated with Fredrickson's type II hyperlipoproteinemia.
**Option B:** Apolipoprotein B-48 is a component of chylomicrons, which are involved in the transport of dietary triglycerides from the intestines to the liver. While apolipoprotein B-48 is involved in lipid metabolism, it is not directly associated with Fredrickson's type II hyperlipoproteinemia.
**Option D:** Apolipoprotein E is a ligand for the LDL receptor and plays a role in the clearance of LDL cholesterol from the bloodstream. However, mutations in the apolipoprotein E gene are associated with a different type of hyperlipoproteinemia, known as type III.
**Clinical Pearl / High-Yield Fact**
Fredrickson's type II hyperlipoproteinemia is often associated with a family history of premature atherosclerotic cardiovascular disease, and individuals with this condition are at increased risk of developing coronary artery disease, stroke, and peripheral artery disease. Early diagnosis and treatment with statins or other lipid-lowering agents can help to reduce the risk of cardiovascular complications.
**Correct Answer:** C. Apolipoprotein B-100