[Integration of genetic factors into epidemiological studies]

Abstract

During the last two decades, genetic epidemiology has been established in parallel to the area of classical epidemiology. This paper presents some essentials of the epidemiology of genetic factors. It begins with a discussion of complex diseases that are characterized by an involvement of several genes. The problems that are attached to modeling gene-gene and gene-environment interactions and their integration into causal pathways are elucidated and the role of genetic factors in the etiology of complex diseases is investigated. Classical and new epidemiological study designs that allow an integration of genetic data are introduced. The introduction of this data is partly motivated by the danger of bias due to genetic heterogeneity (population stratification) in classical designs. The problem of replication of study results is discussed and the concept of Mendelian randomization is presented.