Genotyping of the magnitude required for a consortium such as GENEVA, which includes data on over 80,000 individuals from 16 disparate studies, does not take place on all studies simultaneously. One study's genotyping results arrive for cleaning and quality control checks while other studies' samples are being prepared for or are undergoing genotyping. Therefore genotyping timelines become a critical consideration when planning cross-study analyses. WGs must consider that GWAS results are emerging in the context of sharp competition among various research groups for publication, and there should be an ongoing process to decide when sufficient numbers are available to conduct a study that represents a meaningful advance. WGs may decide to proceed with data analyses when only a few studies are complete and if statistical thresholds are achieved because discoveries relating to the phenotype of interest are emerging so rapidly. The data from studies whose genotype results will be completed later can be used for replication analyses. Alternate strategies might be to wait until more studies' genotype results are available, refine the phenotype definitions so the group can conduct more specific, stratified analyses of key phenotypes, or collaborate with outside consortia doing similar investigations.
