iCOGS is a custom Illumina iSelect genotyping array specifically designed to evaluate genetic variants for association with three hormone related cancers: breast, ovarian and prostate cancer. The Illumina Infinium array included 211,155 SNPs. The array was genotyped in more than 250,000 subjects from case-control studies for breast cancer (through BCAC), ovarian cancer (through OCAC), prostate cancer (through PRACTICAL) and in BRCA1 and BRCA2 carriers (through CIMBA).
The array includes SNPs putatively associated with the risk of these cancers in genome-wide association studies (GWAS), SNPs associated with breast or ovarian cancer risk in BRCA1 or BRCA2 carriers, SNPs associated with subsets of disease (for example, ER-negative breast cancer, serous ovarian cancer and aggressive prostate cancer), SNPs associated with survival after diagnosis, a dense set of SNPs across more than 50 regions known to harbour susceptibility variants for one of the target diseases, SNPs associated with related quantitative traits (e.g. age at menarche, breast density), and functional candidate variants, including rare variants in known cancer susceptibility loci (e.g. BRCA1, PALB2).
Funding for the genotyping has come from multiple sources, with the largest contributors being the European Union Seventh Framework and Cancer Research UK.
The first papers describing the results were published in a series of 13 papers in April 2013, summarised by Nature Genetics in an iCOGS Focus.