Genetic dissection of familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) is the most common genetic hyperlipidemia in man. FCHL is characterized by familial clustering of hyperlipidemia and clinical manifestations of premature coronary heart disease, i.e., before the age of 60. Although FCHL was delineated about 25 years ago, at present the FCHL phenotype and its complex genetics are not fully understood. Initially, the familial aggregation of high plasma total cholesterol and triglyceride levels, with a bimodal distribution of triglycerides, was taken as evidence of a dominant mode of inheritance. However, it is now clear that the genetics of FCHL is more complex, and it has been suggested that FCHL is heterogeneous. Several approaches can be taken to identify genes contributing to the disease phenotype in complex genetic disorders either by studying the disease in the human situation or by using animal models. Recent reports have shown that a combination of genetic linkage studies, association studies, and differential gene expression studies provides a useful tool for the genetic dissection of complex diseases. Therefore, the genetic strategies that will be used to dissect the genetic background of FCHL are reviewed.