Our findings suggest that several cancer-associated genes may have a role in FCCTX, such as the known hereditary cancer gene CHEK2, the previously FCCTX candidate genes OGG1 and FAN1 and, other cancer-related genes such as ATR, ASXL1, PARK2, SLX4 and TREX1, bringing novel insights into the genetic risk factors for familial colorectal cancer type X. Nevertheless, more studies (in vitro and/or in vivo), such as functional assays, segregation, and loss of heterozygosity, are necessary to ascertain more conclusive hypotheses about their role in FCCTX predisposition. This evidence concerns the gene CHEK2 and familial colorectal cancer type X.