Dissecting the genetic architecture of lipids, lipoproteins, and apolipoproteins lessons from twin studies

We review the ways in which twin studies have been used to investigate the genetic architecture of lipids, lipoproteins, and apolipoproteins. We focus on the age dependency of genetic effects and the importance of pleiotropy for the lipid system. Finally, consequences are discussed of age dependency and pleiotropy for the design and power of twin studies aimed at detecting the actual quantitative trait loci (QTLs) involved. It is concluded that t win studies have played an important role and will remain highly valuable f or the elucidation of the genetic architecture of lipids, lipoproteins, and apolipoproteins. Twins can efficiently be used to identify the location an d function of QTLs. Taking account of pleiotropy and age-dependent gene exp ression in study design and data analysis will improve the power and effici ency to find these QTLs for components of the lipid system.