Lipoprotein, a (Lpa)

Lipoprotein(a) consists of an LDL-like particle and the specific apolipoprotein(a) , which is covalently bound to the apoB of the LDL like particle. Lp(a) plasma concentrations are highly heritable and mainly controlled by the apolipoprotein(a) gene located on chromosome 6q26-27. Apo(a) proteins vary in size due to a size polymorphism , which is caused by a variable number of so called kringle IV repeats in the LPA gene. This size variation at the gene level is expressed on the protein level as well, resulting in apo(a) proteins with 10 to > 50 kringle IV repeats . These variable apo(a) sizes are known as "apo(a) isoforms". There is a general inverse correlation between the size of the apo(a)isoform and the Lp(a) plasma concentration which is caused by a variable rate of degradation before the apo(a) protein has matured for Lp(a) assembly.