[Biological Markers in Epidemiology: Concepts, applications, Perspectives (Part II)].

The first part of this paper outlined terms and definitions in the context of the application of biological markers in epidemiological studies. Cardiovascular epidemiology served as an example for their historical development. The second part focusses on DNA-based biomarkers, practical and methodological dimensions of the use of biomarkers in analytic epidemiological studies as well as requirements in respect of validity and quality assurance. Most genetic polymorphisms have no impact on health. However, some can be used as biomarkers for individual sensitvity to exposures and susceptibility for specific diseases. The Human Genome Project has brought about a quantum leap in the development of genetic markers. The practical implications cannot presently be assessed with certainty. However, present and future research programmes of gene-environment interactions depend on "traditional" epidemiological study designs, methods, and concepts. Ethical principles and data protection requirements apply equally to genetic and molecular epidemiology as do the "Guidelines for Good Epidemiological Practice".