The inherent complexities of gene-environment interactions.

The article outlines the complexities of gene-environment interactions in the determination of human disease, especially as they relate to aging, and stresses the importance of continuing such studies, in spite of their inherent difficulties. First, a capsule review of the literature pertaining to studies of gene-environment interactions is presented, and designs and methodologies used to detect these interactions are briefly discussed. Second, research questions and problems that can be addressed as outcomes of gene-environment interaction studies are exemplified. Third, a number of illustrative examples of gene-environment interactions are presented. Fourth, various types of gene-environment interactions are briefly discussed. Fifth, concluding remarks are offered, and possibilities of studying gene-environment interaction within social and biological research on aging are outlined.