Novel recurrently mutated genes in African American colon cancers

Significance Colorectal cancer is a leading cause of cancer-related deaths world-wide. African Americans exhibit the highest colon cancer incidence and mortality among all ethnic groups in the United States. Despite this finding, there is a dearth of knowledge on the genetic mechanisms underlying colon carcinogenesis in African Americans. We thus initiated this study to characterize the mutational landscapes of African American colon cancers. We identified new genes that are significantly mutated in colon cancer and that are highly preferentially targeted for mutations in colon cancers arising in African Americans as compared with Caucasians. These findings suggest differences in routes of colon carcinogenesis between the different ethnic groups and also may have implications for the ethnicity associated differences in tumor incidence and outcome. We used whole-exome and targeted sequencing to characterize somatic mutations in 103 colorectal cancers (CRC) from African Americans, identifying 20 new genes as significantly mutated in CRC. Resequencing 129 Caucasian derived CRCs confirmed a 15-gene set as a preferential target for mutations in African American CRCs. Two predominant genes, ephrin type A receptor 6 ( EPHA6 ) and folliculin ( FLCN ), with mutations exclusive to African American CRCs, are by genetic and biological criteria highly likely African American CRC driver genes. These previously unsuspected differences in the mutational landscapes of CRCs arising among individuals of different ethnicities have potential to impact on broader disparities in cancer behaviors.