Avon Longitudinal Study of Parents and Children ALSPAC : A national resource for the elucidation of environmental and genetic influence on health and development. (360G-Wellcome-062199_Z_00_Z)

Most determinants of human health and development arise from interactions between genetic variation and environmental pressures. The classification of many diseases is currently based primarily on descriptions of symptoms or biochemical abnormalities, but there is now increasing evidence that these definitions mask substantial heterogeneity of underlying traits . Susceptibility or resistance to pre-morbid changes in these traits and the common disorders to which they contribute, is likely to be bestowed by one or more (common) genetic polymorphisms, the impact of which will change as various environmental and developmental stresses change. As the Western world has become more affluent there has been a decrease in prevalence of many severe infections. However this has been counterbalanced by an increase in many disorders such as asthma and allergies, obesity, and a variety of behaviour disorders. Although there are clear family clusters within each of these outcomes, indicating a genetic susceptibility, changes in the environment must be the main causes of these increases. There are good reasons why the strategy to determine the genetic and environmental features that are currently important should incorporate genetic variation and other direct biological information into longitudinal, population-based epidemiological studies of common disorders. In the same way that efficient early progress in constructing maps of the human genome required integration within a master set of families, so data on gene/environment and gene/gene interactions in common disorders or physiological/behavioural traits needs integration within a single population sample if maximum information is to be gained from a major investment in genetic epidemiology.