This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of lipid, Subject name: Biochemistry
Type 2 hypercholesterolemia occurs due to 
Select and explain. 
A. Lipoprotein lipase deficiency, B. Absence of LDL receptors on cells, C. Abnormality in apo E, D. LCAT deficiency
B: Absence of LDL receptors on cells
Answer: B: Absence of LDL receptors on cells 
Explanation: Type II A(Primary familial hypercholesterolemia) There is elevation of LDL. Patients seldom survive the second decade of life due to ischemic hea disease (Table 25.4). The cause is LDL receptor defect. Receptor deficiency in liver and peripheral tissues will result in the elevation of LDL levels in plasma, leading to hypercholesterolemia. The LDL receptor defect may be due to the following reasons:LDL receptor deficiency.Defective binding of B-100 to the receptor. A substitution of glutamine for arginine at 3500thamino acid results in poor binding to LDL receptors. This defect is known as B-3500 or familial defective apo-B.Receptor-LDL complex is not internalised. Secondary type II hyperlipoproteinemia is seen in hypothyroidism, diabetes mellitus, nephrotic syndrome and cholestasis