Genetic epidemiology in a molecular age

Abstract

In this issue we publish three genetic epidemiology papers (Agrawal et al. 2002; Johnson et al. 2002; Wichers et al. 2002). Psychological Medicine in recent years has had genetic epidemiology as one of its major themes. We also publish some molecular genetic papers. This is a time when the development of molecular genetic technologies, which have already enabled the sequencing of the entire human genome, has been widely and appropriately hailed as a major advance, promising to generate a revolution in the understanding of causes of all human disease, including psychiatric, and in the discovery of new drugs. Psychological Medicine now has a distinguished American Editor from the world of genetic epidemiology in the person of Kenneth Kendler. This editorial, by his British editorial counterpart, is deliberately non-expert, and a view of the psychiatric future of genetic epidemiology from outside the field.

The basic findings for heritability of major psychiatric disorders have become well established and replicated in some decades of research. Family studies were followed by twin studies and adoption studies which established on a much firmer basis that a substantial element in the familiality was genetic. Disappointingly, the genes still remain to be identified with certainty. That is the task of molecular genetics. It is becoming increasingly clear that the task will not be an easy one, because for the most part we seem to have multi-gene disorders, with a number of or many genes of small effect, requiring large samples and quantitative trait methods to elucidate (Plomin et al. 1994).