Genetic Aspects of High Variability of Lipoprotein(a) Levels

Overview

Increased levels of lipoprotein(a) are supposed to be an independent risk factor for atherosclerosis. Apolipoprotein(a) determines structural and functional characteristics of the lipoprotein particle. The lipoprotein(a) concentration is almost entirely genetically determined at the apolipoprotein(a) gene locus, nevertheless it varies widely between individuals in all populations studied so far. Large part of the variance is correlated to the apolipoprotein(a) gene length polymorphism. Some of the variance could be additionally related to polymorphic sites either in the coding sequence or in the transcription regulatory regions. Only a few functional variants were discovered in the coding sequence of apolipoprotein(a) gene so far. Moreover, analyses of relevant regulatory regions (promoter, DHII and DHIII enhancers) have revealed less variability than was expected. Despite the lipoprotein(a) levels are under dominant control of a single locus its genetic determination is quite complex. The basic role belongs to the apolipoprotein(a) gene length polymorphism and to a panel of sequence variants affecting apolipoprotein(a) gene expression and lipoprotein(a) particle production rate. Besides, minor impact of other locuses and modulation by non–genetic factors should be considered. 

Key words:
apolipoprotein(a), lipoprotein(a), polymorphism, promoter, enhancer.