To further dissect the genetic architecture of colorectal cancer (CRC), we performed whole-genome sequencing of 1,439 cases and 720 controls, imputed discovered sequence variants and Haplotype Reference Consortium panel variants into genome-wide association study data, and tested for association in 34,869 cases and 29,051 controls. Findings were followed up in an additional 23,262 cases and 38,296 controls. We discovered a strongly protective 0.3% frequency variant signal at CHD1 . In a combined meta-analysis of 125,478 individuals, we identified 40 new independent signals at P <5×10 −8 , bringing the number of known independent signals for CRC to approximately 100. New signals implicate lower-frequency variants, Krüppel-like factors, Hedgehog signaling, Hippo-YAP signaling, long noncoding RNAs, somatic drivers, and support a role of immune function. Heritability analyses suggest that CRC risk is highly polygenic, and larger, more comprehensive studies enabling rare variant analysis will improve understanding of underlying biology, and impact personalized screening strategies and drug development.

Recent evidence indicate that small non-coding RNA molecules, called micro-RNAs (miRNAs), can bind to the 3' untranslated regions (UTRs) of messenger RNAs and interfere with their translation, thereby regulating cell growth, differentiation, apoptosis and tumorigenesis. Genetic polymorphisms can reside on miRNA-binding sites. Thus, it is conceivable that the miRNA regulation may be affected by polymorphisms on the 3' UTRs. Since gene deregulation is one of the key mechanisms by which cells can progress to cancer, we hypothesize that common polymorphisms within miRNA-target binding sites could play a role in the individual risk of cancer. In the present study, we selected the 3' UTRs of 104 genes candidate for colorectal cancer (CRC) and we identified putative miRNA-binding sites by specialized algorithms (PicTar, DianaMicroT, miRBase, miRanda, TargetScan and microInspector). Fifty-seven single-nucleotide polymorphisms (SNPs) were identified in miRNA-binding sites. We evaluated the SNPs for their ability to affect the binding of the miRNA with its target, by assessing the variation of Gibbs free energy between the two alleles of each SNP. We found eight common polymorphisms that were further investigated by a case-control association studies. The study was carried out on a series of cases and controls from Czech Republic, a population with the highest worldwide incidence of CRC. We found statistically significant associations between risk of CRC and variant alleles of CD86 [odds ratio (OR) = 2.74; 95% confidence interval (CI) = 1.24-6.04, for the variant homozygotes] and INSR genes (OR = 1.94; 95% CI = 1.03-3.66, for the variant homozygotes). These results are the first reporting positive association between miRNA-binding SNPs sequences and cancer risk.