Thus, assumptions about power and sample size required revision; studies which seemed well-powered when they began were too small. It became obvious that larger sample sizes were needed and groups working together were the only practical way to achieve this end. Consortia were thus an immediate solution. The concept of working together was influenced by the experiences of other biomedical disorders. For example, the initial three GWAS for type 2 diabetes mellitus were only modestly successful but joint analysis revealed many more strongly significant associations (Zeggini et al. 2008).
