On laboratory investigations in a patient, LDL was highly elevated but the level of LDL receptors was normal. Which of the following is most probable cause?
Phosphorylation of LDL receptors
Lipoprotein lipase deficiency
Apo B-100 mutation
Cholesterol Acyl Co-A transferase deficiency
Ans: C. Apo B-100 mutationIn Type Ila Familial hypercholesterolemia:Highly elevated levels of LDL with normal level of LDL receptors.Characterized mutation in ligand region of apoB-100.Differential diagnosis:"Familial Defective apoB-100 (FDB)"/"Autosomal dominant hypercholesterolemia (ADH) type 2":Dominantly inherited disorder.Clinically resembles heterozygous familial hypercholesterolemia (FH) with elevated LDL-C levels and normal TGs.FDB - Caused by mutations in gene encoding apoB-100, specifically in LDL receptor-binding domain of apoB-100.Ref (Harrison 19/e p2438-2447, 18/e p3148)