Which of the following is increased in LCAT deficiency?
**Core Concept**
LCAT (Lecithin-Cholesterol Acyltransferase) is an enzyme that plays a crucial role in the formation of cholesteryl esters in the plasma. It is involved in the maturation of high-density lipoprotein (HDL) and the removal of excess cholesterol from peripheral tissues to the liver for excretion.
**Why the Correct Answer is Right**
LCAT deficiency leads to an accumulation of unesterified cholesterol in the plasma, resulting in an increase in levels of unesterified cholesterol. This condition is known as fish-eye disease due to the characteristic appearance of the corneas under slit-lamp examination. The increased unesterified cholesterol levels are due to the impaired conversion of unesterified cholesterol to cholesteryl esters, which is a key function of the LCAT enzyme.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because LCAT deficiency does not directly affect the levels of triglycerides in the plasma.
**Option B:** This option is incorrect because LCAT deficiency does not directly affect the levels of LDL cholesterol in the plasma.
**Option C:** This option is incorrect because LCAT deficiency does not directly affect the levels of HDL cholesterol in the plasma; rather, it impairs the maturation of HDL.
**Clinical Pearl / High-Yield Fact**
LCAT deficiency is a rare genetic disorder that can lead to premature atherosclerosis and increased risk of cardiovascular disease due to the accumulation of unesterified cholesterol in the plasma.
**Correct Answer: C. Unesterified cholesterol**