[General topics in abnormalities of lipoprotein metabolism]

Level of plasma cholesterol and triglycerides are regulated by a dynamic equilibrium between diet-derived exogenous supply and endogenous synthesis and degradation. The metabolism of lipoproteins such as chylomicron, VLDL, IDL, LDL and HDL, carrying cholesterol and triglycerides is regulated strictly by specific apoprotein constituents of these lipoprotein classes and its receptors. In addition, the metabolism of chylomicron and VLDL is also regulated by lipoprotein lipase on the surface of arterial wall. Current knowledge of the processes of lipid transport, such as cholesterol and triglycerides in the blood owes much to discoveries of major gene mutations affecting the apoproteins, key enzymes that control lipid transport, and cellular receptors that recognize specific apoproteins. It is, indeed, difficult to imagine how this field (lipoprotein metabolism) could have reached its present state in the absence of discoveries, which resulted from many clinical investigations of patients manifesting abnormalities of the plasma lipoproteins. General topics in lipoprotein metabolism and its abnormalities are summarized here.