What is the common characteristic of familial hypercholesterolemia?

Familial hypercholesterolemia is primarily characterized by a genetic defect in the low-density lipoprotein (LDL) receptors. This defect impairs the body's ability to clear LDL cholesterol from the bloodstream effectively, leading to elevated levels of LDL cholesterol. The condition is inherited in an autosomal dominant manner and results in significantly increased cholesterol levels, which contribute to early-onset atherosclerosis and related cardiovascular diseases.

The other options do not accurately describe familial hypercholesterolemia. Elevated levels of HDL are typically considered protective against cardiovascular risk and do not characterize this condition. A deficiency of Apo E is more related to disorders such as Type III hyperlipoproteinemia rather than familial hypercholesterolemia. Increased triglycerides without elevation of cholesterol would indicate different metabolic issues and does not align with the high LDL levels seen in familial hypercholesterolemia. Thus, the defect in LDL receptors leading to high LDL levels is the most defining and characteristic feature of this condition.