Which of the following is/are true regarding cholesterol?

a. Cholesterol ester rich LDLs are removed from the circulation primarily by the liver utilizing the apo B-E receptor

b. Receptor mediated clearance reduces de novo cholesterol synthesis

c. Elevations of LDL alone constitute Type IIa familial hypercholesterolemia

d. Elevated LDLs and VLDLs constitute Type IIb (familial combined)

Receptor mediator clearance of cholesterol rich LDL are accomplished by means of apo B-E receptors. This clearance reduces the de novo production of cholesterol by inhibiting the activity of hydroxymethylglutaryl co-enzyme A (HMG CoA) which catalyzes the rate limiting step in cholesterol synthesis. Isolated LDL elevations constitute Type IIa hypercholesterolemia whereas elevated LDLs and VLDLs constitute Type IIb. Both are associated with coronary artery disease and peripheral vascular lesions. Type IIa exists in heterozygous form in the population in 1:500 individuals and Type IIb may occur in as many as 1:50 people.