**Question:** In case of LPL deficiency, which of the following will increase after a fat rich diet?

**Core Concept:** LPL (Lipoprotein Lipase) deficiency is a rare genetic disorder that affects the ability to break down triglycerides in the bloodstream, leading to hypertriglyceridemia. Triglycerides are a type of fat molecule found in blood and are broken down by an enzyme called LPL.

**Why the Correct Answer is Right:** After consuming a diet rich in fat, the body increases the production of triglycerides to store excess energy. However, in LPL deficiency, the enzyme LPL is not functioning properly, leading to an accumulation of triglycerides in the blood. As a result, the liver will try to compensate for the lack of LPL by increasing the production of VLDL (Very Low Density Lipoprotein) particles. VLDL particles contain triglycerides and are converted into other lipoproteins like LDL (Low Density Lipoprotein) and HDL (High Density Lipoprotein).

**Why Each Wrong Option is Incorrect:**

A. **Incorrect:** After consuming a fat-rich diet, the liver would normally increase the production of VLDL to remove excess triglycerides. In LPL deficiency, this compensatory mechanism fails, leading to increased triglycerides and VLDL production.

B. **Incorrect:** While the liver tries to remove excess triglycerides by increasing VLDL production, this option is incorrect because the liver also responds to increased triglycerides by secreting more ApoB, the protein that forms the basis of VLDL particles, rather than ApoE, which would lead to increased VLDL production.

C. **Incorrect:** The liver secretes ApoE, which is involved in the transport and removal of triglycerides and cholesterol from the bloodstream. This option is incorrect because ApoE is not involved in the increase of VLDL production, unlike ApoB, which is involved in the production of VLDL.

D. **Incorrect:** ApoB is involved in the production of VLDL particles to remove excess triglycerides from the bloodstream, but in LPL deficiency, this mechanism fails, leading to increased VLDL production.

**Clinical Pearl:**

Understanding the role of ApoE and ApoB in the liver's response to increased triglycerides is crucial for the proper management of patients with LPL deficiency. Knowing the correct mechanism helps in identifying and treating this rare genetic disorder, preventing complications like chylomicronemia and pancreatitis.