In primary familial hypercholesterolemia, there is defect in:

Ans. (a) LDL-receptorsRef: Harper's Biochemistry, 30th ed. pg. 275* Familial hypercholesterolemia is a genetic disorder characterized by high cholesterol levels, specifically very high levels of low-density lipoprotein in the blood and early cardiovascular disease.* These patients have mutations in the LDLR gene that encodes the LDL receptor protein, which normally removes LDL from the circulation.* The high cholesterol levels in FH are less responsive to the kinds of cholesterol control methods that are usually more effective in people without FH (such as dietary modification and statin tablets), because the body's underlying biochemistry is slightly different. However, treatment (including higher statin doses) can often be successful.* Heterozygous FH is normally treated with statins, bile acid sequestrants or other hypo-lipidemic agents that lower cholesterol levels.* Homozygous FH often does not respond to medical therapy and may require other treatments, including LDL apheresis (removal of LDL in a method similar to dialysis) and occasionally liver transplantation.