What mechanism causes elevated plasma levels of beta lipoproteins in familial hypercholesterolemia?

Familial hypercholesterolemia is primarily associated with a defect in the receptor for Apo B-100, which is involved in the uptake of low-density lipoprotein (LDL) cholesterol from the bloodstream. Apo B-100 is a crucial component of LDL particles, and its receptor specifically mediates their clearance from circulation by the liver.

In individuals with familial hypercholesterolemia, mutations in the LDL receptor gene lead to a dysfunctional receptor that cannot effectively bind to LDL particles. As a result, these particles remain in the bloodstream for an extended period, leading to an accumulation of beta lipoproteins, particularly LDL. This accumulation is what causes the elevated plasma levels of beta lipoproteins seen in this condition.

The other choices relate to different lipid metabolism mechanisms and disorders, but they do not specifically account for the mechanism underlying familial hypercholesterolemia. For instance, Apo E receptor defects impact chylomicron and intermediate-density lipoprotein metabolism but not specifically the beta lipoprotein level increase associated with familial hypercholesterolemia. Apo A-1 deficiency is primarily associated with low high-density lipoprotein (HDL) levels, affecting cholesterol transport in the opposite way. Increased hepatic lipase activity generally would not lead