Lipoprotein(a): a genetically determined cardiovascular pathogen in search of a function.

Lipoprotein(a) (Lp(a)) is a genetically-determined lipoprotein variant with a lipid composition similar to that of low-density lipoproteins (LDL) and a protein moiety consisting of apolipoprotein B-100 (apoB100) linked covalently to apolipoprotein(a) (apo(a)), which is a glycoprotein with a striking structural similarity to plasminogen. One of the characteristics of plasma Lp(a) is to vary widely in concentration and to be heterogeneous in size and density. Apo(a) also exhibits an important size heterogeneity that is related to the number of kringle 4 domains under the control of the apo(a) gene. Epidemiologic studies have linked high plasma levels of Lp(a) to an increased prevalence of atherosclerotic cardiovascular disease by yet undefined mechanisms. It is possible that because of its unique structural features, Lp(a) may have both atherogenic and thrombogenic actions.