Lipoprotein(a): a link between thrombosis and atherosclerosis?

Lipoprotein(a) (Lp(a)) represents a class of plasma lipoproteins similar to low-density lipoprotein (LDL), but containing an unique apolipoprotein(a) with striking homology to plasminogen. Plasma Lp(a) is inherited as a quantitative genetic trait, with a continuous distribution in Caucasian populations (< 10-2000 mg/l), where high levels are associated with an increased risk of atherosclerotic disease. The physiological role of Lp(a) is unknown, and the metabolism is obscure. Plasma Lp(a) is apparently resistent to diets and drug therapy, and LDL-apheresis is currently the most effective way of reducing plasma Lp(a). However, clinical benefits of lowering plasma Lp(a) have not been demonstrated, and specific therapeutic goals cannot be recommended at present. The structural similarity between apo(a) and plasminogen has generated several experimental observations indicating a prothombogenic and proatherogenic role of Lp(a), but the exact pathophysiological mechanisms have not been determined.