Meta-analysis of gene-environment interactions in developmental psychopathology.

As studies of measured gene-environment interactions (G x E) in developmental psychopathology gain momentum, methods for systematically and quantitatively summarizing effects across multiple studies are urgently needed. Meta-analyses of G x E findings are critical for evaluating the overall statistical and theoretical significance of any given G x E based on cumulative and systematically combined knowledge. Although meta-analytic methods for the combination of study findings based on single effect measures such as odds ratios and mean differences are well established, equivalent methods for the meta-analysis of studies investigating interactions are not well developed. This article describes one simple approach to the meta-analysis of G x E effects using, as a contemporaneous example, the interaction of the monoamine oxidase A (MAOA) gene and the impact of childhood maltreatment on risk for developing antisocial behavior.