Massive parallel sequencing in a family with rectal cancer.

Background: We have previously reported a family with a suspected autosomal dominant rectal and gastric cancer syndrome without any obvious causative genetic variant. Here, we focused the study on a potentially isolated rectal cancer syndrome in this family.

Methods: We included seven family members (six obligate carriers). Whole-exome sequencing and whole-genome sequencing data were analyzed and filtered for shared coding and splicing sequence and structural variants among the affected individuals.

Results: When considering family members with rectal cancer or advanced adenomas as affected, we found six new potentially cancer-associated variants in the genes CENPB, ZBTB20, CLINK, LRRC26, TRPM1, and NPEPL1. All variants were missense variants and none of the genes have previously been linked to inherited rectal cancer. No structural variant was found.

Conclusion: By massive parallel sequencing in a family suspected of carrying a highly penetrant rectal cancer predisposing genetic variant, we found six genetic missense variants with a potential connection to the rectal cancer in this family. One of them could be a high-risk genetic variant, or one or more of them could be low risk variants. The p.(Glu438Lys) variant in the CENPB gene was found to be of particular interest. The CENPB protein binds DNA and helps form centromeres during mitosis. It is involved in the WNT signaling pathway, which is critical for colorectal cancer development and its role in inherited rectal cancer needs to be further examined.