The WTCCC study has been described elsewhere7. Cases were recruited from pediatric and adult diabetes clinics at 150 National Health Service Hospitals across Great Britain as part of the Genetic Resource for Investigating Diabetes (GRID) collection (www.childhood-diabetes.org.uk/grid.shtml) of the JDRF/WT DIL9. Half of the controls were drawn from the British 1958 Birth Cohort21 and half from a group of blood donors recruited by the WTCCC in collaboration with the UK Blood Services7. The former group was subsequently genotyped on the Illumina 550K platform and was used as controls in the new T1DGC study reported here. Since the removal of this group from the WTCCC study left it somewhat short of controls, we used a group of 1,868 patients with bipolar disorder as additional reference samples — a group conspicuous in the WTCCC studies in its lack of significant differences from control allele frequencies7.
