The Avon Longitudinal Study of Parents and Children (ALSPAC): a resource for genetic epidemiology.

The Avon Longitudinal Study of Parents and Children (ALSPAC) has collected detailed phenotypic and environmental information from pregnancy onwards on approximately 14 000 babies born in 1991-1992. A DNA bank on over 10 000 mothers and children has been established with generic consent for (undisclosed) genetic analysis, and cell lines on both children and parents are planned. As a multigenerational population cohort unselected by disease, trait or exposure, ALSPAC is uniquely placed to explore the genetic and environmental determinants of adverse developmental responses and common disease. Added value for genetic epidemiology generally is the ability to detect distortion of the expected Mendelian 50:50 transmission of alleles to study subjects (e.g. due to differential loss of embryos of one genotype) or to test for heterosis, i.e. whether heterozygotes have a greater or lesser effect than either homozygote. Finally, phenome scans (a fixed format analysis of the associations between a genotype of interest and thousands of outcome variables from the cohort database) could be used as a screening tool to test whether certain classes of genetic variation have more impact than others on human health and development.