The use of cases and a random cohort nested in EPIC enabled Interact partners to jointly ascertain and verify a total of 12,403 incident type 2 diabetes cases in a relatively short time frame, exceeding the originally estimated number. Extraction of DNA in cases and in the randomly selected subcohort and storage in a comPOUND® (TTP LabTech, Cambridge, UK) automatic DNA handling system allows rapid genotyping that together with standardised baseline information on participants’ clinical characteristics and health behaviour enables investigation of the interaction between genes and lifestyle factors. Genome-wide data on a stratified InterAct sample of 10,000 participants provides the opportunity for discovery of as yet unidentified variants whose larger subgroup effects may have introduced sufficient heterogeneity in non-stratified, conventional GWAS to prevent them from reaching the stringent significance levels required in this setting.
