Genetic disorders of hdl metabolism

Metabolism, function, and plasma levels of high-density lipoprotein (HDL) are influenced by genetic factors. Monogenic disorders causing very low and very high HDL levels, such as Tangier and fish-eye disease on one side, cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) deficiency on the other, are rare but important for the clinician to recognize. More common is an interaction between environment and heredity causing less drastic but clinically significant phenotypes. Recent development in our understanding of HDL biosynthesis, catabolism, and action, combined with the failure of trials with HDL-raising drugs, challenges the dogma that high HDL levels protect the vessel wall and low HDL syndromes lead to increased atherosclerosis. The novel concept of HDL functionality may take the place of HDL concentrations as predictor of coronary disease rates. It is not currently known whether HDL functionality is an inherited trait. This chapter reviews HDL metabolism, outlines known inherited aberrations, and considers the potential implications of current research.