Since 2005 (1), genomewide association studies (GWAS, “jē’ wōs”) have produced strongly significant evidence that specific common DNA sequence differences among people influence their genetic susceptibility to over 40 different common diseases. (2). Many of these findings implicate previously-unsuspected candidate genes and new pathophysiological hypotheses. The method is feasible because millions of human DNA sequence variations have been catalogued, and new technologies developed that can assay over one million variants rapidly and accurately. The first GWAS reports have appeared for psychiatric disorders, and close to 50 GWAS of attention-deficit hyperactivity disorder, autism, bipolar disorder, major depressive disorder and schizophrenia should be completed by the end of 2008, with more to come. The present authors have formed an international consortium of psychiatric GWAS investigators to carry out rapid meta-analyses of these five disorders to maximize power. Here we describe GWAS methods, their rationale and current results for non-psychiatric and psychiatric disorders, and discuss some limitations and uncertainties.
