The Georgia Cardiovascular Twin Study is a longitudinal study of biobehavioral antecedents of cardiovascular disease in youth. It includes roughly equal numbers of African Americans and European Americans, with a total of > 500 twin pairs. Focus of the study is the change in relative influence of genetic and environmental factors on development of risk factors for cardiovascular disease. Future work will explore the influence of polymorphic variation in candidate genes and their potential interaction with the environment on these risk factors.

This paper describes the Pittsburgh Registry of Infant Multiplets (PRIM; Pittsburgh, Pennsylvania), the results of pilot research conducted in this registry, and the plans for future studies. The main focus of the registry is on psychological development and the risk for behavioral disorders. Particularly, characteristics associated with antisociality and the risk for substance use disorders (e.g., aggressivity, hyperactiv-ity/impulsivity), as well as language development and other traits (e.g., dental health) are among the research targets.

The Wisconsin Twin Panel was initiated in 1994 to serve a study of the development of childhood mood and behavioral disorders. Families who give birth to twins within the state of Wisconsin are recruited within 6 months of the birth. The panel currently supports three ongoing, longitudinal research projects. Research foci include studying epigenetic contributions to emotional, physical, cognitive, and motoric development of infant and toddler twins; physiological concomitants of childhood temperament; and early risk and resiliency factors related to child psychopathology. All three studies include videotaped observational assessments and biological measures.