A genome-wide association study of colorectal cancer in Mexican mestizos suggest novel common tumor-risk variants

Background: Genome-wide association studies (GWAS) for colorectal cancer (CRC) have detected high-risk genetic variants associated with CRC in several ethnic groups, but Latin American communities are still underrepresented. The aim was to identify variants related to CRC in an admixed Latin American population. Methods: The study was performed in 831 cases and 881 controls from Mexico, who were genotyped for 1,006,703 autosomal SNPs. Logistic regression was carried out including covariants, such as sex, age and genetic ancestry. Lastly, we performed a sequence-kernel association test (SKAT) to consider the joint effect of several SNPs lying in genes.Results: Eight chromosomal regions reached genome-wide significance level ( p < 5×10 -8 ): 1p36.22, 1p31.1, 1q42.13, 6p22, 7p14.1, 12q24.32, 16q12.2 and 21q22.2 and 63 variants reached borderline statistical significance ( p < 1×10 − 6 ). SKAT analysis detected 13 loci associated with CRC, none of them previously associated with CRC. Conclusions: We found 8 SNPs and 13 loci associated with CRC. These signals may contribute to enrich the panoply of genes involved with CRC. Further analyses remain to be done to validate the associations in other Latin American populations. This study highlights the importance of conducting GWAS in poorly explored admixed populations.