Large-scale, collaborative meta-analysis has the potential to clarify complex scientific questions by increasing sample size, harmonizing variables, and conducting uniform analyses. In this paper, we describe the protocol for a collaborative, consortium-based meta-analysis to increase understanding of the role of 5-HTTLPR variation and stress in depression. The publication of this protocol serves several important purposes. First, we document our study protocols, design, and primary analysis decisions prior to conducting and publishing our study of 5-HTTLPR variation, stress, and depression, which will avoid biased reporting later. Second, publication of these details will improve the ability of other researchers to interpret the results of this specific meta-analysis upon its completion. Finally, publishing our detailed protocol may be helpful to future consortia by detailing key analysis strategies and as a standard for transparency and commitment to analytic plans set prior to meta-analysis.
