During the past decade, a substantial shift has emerged from investigating genetic vulnerability or environmental risk factors underlying severe mental disorders, to a combination of both – in other words, a shift towards gene x environmental interactions studies. Recently, international genome wide association studies (GWAS) have identified novel disease-susceptibility genes in schizophrenia and bipolar disorder (Ripke et al., 2011;Sklar et al., 2011). Still, the identified genetic variants explain only a small fraction of disease susceptibility (Maher, 2008). In addition to the interaction between different genetic factors (i.e. epistasis), it is most probably also due to moderation by environmental risk factors, such as obstetric complications, early childhood trauma, migration, and the effect of cannabinoids.
The goal of this Research Topic is to bring together a wide range of research on the field of gene x environmental interactions in severe mental disorders. We will mainly focus on early trauma and other stressors; however other environmental risk factors will also be included. This Research Topic will contribute by expanding the knowledge on gene x environmental interactions in schizophrenia spectrum and bipolar disorders, with the goal of providing new insights into the etiology of severe mental disorders. We plan a broad scope of subjects for this unique volume and we welcome original research and review papers from both basic science and clinical studies. We are certain that our Topic is both timely and important, and that it will have a clear scientific, as well as clinical relevance.

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.