In Abetaltipoproteinemia result in absence of:
**Core Concept**
Abetalipoproteinemia is a rare inherited disorder characterized by the inability to synthesize very-low-density lipoprotein (VLDL) and chylomicron particles due to a deficiency in the microsomal triglyceride transfer protein (MTTP). This results in the absence of apolipoproteins B-48 and B-100, leading to impaired lipid absorption and transport.
**Why the Correct Answer is Right**
The correct answer is D. All because Abetalipoproteinemia affects the production of all three lipoproteins: VLDL, chylomicrons, and LDL. This is due to the impaired assembly and secretion of lipoproteins from the liver and intestine. As a result, patients with Abetalipoproteinemia exhibit a complete absence of these lipoproteins in their plasma. The deficiency of apolipoprotein B-48 in chylomicrons and apolipoprotein B-100 in VLDL and LDL particles leads to impaired lipid transport and absorption, resulting in malabsorption of fats and fat-soluble vitamins.
**Why Each Wrong Option is Incorrect**
**Option A:** Chylomicrons are indeed affected in Abetalipoproteinemia, but the question is asking for the absence of all lipoproteins. Chylomicrons are only one of the three lipoproteins affected.
**Option B:** LDL is affected in Abetalipoproteinemia due to the impaired production of VLDL, which is the precursor to LDL. However, the question asks for the absence of all lipoproteins, and LDL is not the only affected lipoprotein.
**Option C:** VLDL is affected in Abetalipoproteinemia due to the impaired production of VLDL particles by the liver. However, the question asks for the absence of all lipoproteins, and VLDL is not the only affected lipoprotein.
**Clinical Pearl / High-Yield Fact**
Abetalipoproteinemia is a rare genetic disorder that highlights the importance of the microsomal triglyceride transfer protein (MTTP) in lipid metabolism. The impaired assembly and secretion of lipoproteins from the liver and intestine lead to a complete absence of VLDL, chylomicrons, and LDL particles in the plasma, resulting in malabsorption of fats and fat-soluble vitamins.
**✓ Correct Answer: D. All**