Merging genetics and epidemiology: What is in it for public health?

Abstract

The results of the human genome project were published and celebrated at the turn of the millennium as a milestone in our understanding of human biology [1,2]. Genetics has drawn enormous attention from the research community, the general population, media, policy-makers, gene-ethics activists, and investors over the last 15 years. Expectations are high concerning future diagnostic and treatment opportunities, although it is not at all clear when preventive measures and treatments will materialize as a result of new genetic knowledge. Sceptics claim that the ethical problems, social and political considerations, environmental factors, prevention, and public health perspectives are neglected, and that the aetiological significance of genetic factors is wildly exaggerated to promote genetics. Why should people in public health be interested in genetics? What can epidemiologic research gain from integrating genetics? And what can epidemiology provide for genetic research? Historically it is the rule, rather than the exception, that new knowledge is met by scepticism and fear on one hand, and is exaggerated and oversold on the other hand. Also, in most cases it takes a long time between the identification of causes of diseases and the development of technologies (i.e. drugs and vaccines) and political ability to implement treatment or prevention practices that are efficient (i.e. regulation against smoking). Susser and Susser [3] divide the history of epidemiology into three eras: the sanitary era (approximately 1840–90), the infectious disease era (approximately 1890– 1950), and the era of risk factor epidemiology (approximately 1950–2000). The sanitarians were socially and politically concerned with all aspects of society, and had some success in improving sanitary conditions. However, some of the leaders believed so strongly in miasma that they fought hard against the competing theory on germs as the cause of infectious diseases. In the infectious disease era the central paradigm was germs. Public health institutions developed into laboratories. Germs were seen as the only causal factors of interest, while other environmental, societal, and political factors where sometimes ignored. As infectious diseases came under control in Europe and North America, and cancer and cardiovascular diseases became the major causes of death, risk factor epidemiology developed with‘ a focus on environmental factors related to lifestyle, behaviour, and social class. The question is: What era are we moving into now? Some will say that we are already well into the genomic or postgenomic era, and that this era has similarities to the infectious disease era with its limited monocausal views and ignorance of other aetiological factors. I hope that the era we are moving into will be a result of merging epidemiology and genetics to accomplish scientific achievements that are impossible without both.