Scarce evidence of the causal role of germline mutations in UNC5C in hereditary colorectal cancer and polyposis
PI13-00285 PI11-01439 ; Germline mutations in UNC5C have been suggested to increase colorectal cancer (CRC) risk, thus causing hereditary CRC. However, the evidence gathered thus far is insufficient to include the study of the UNC5C gene in the routine genetic testing of familial CRC. Here we aim at providing a more conclusive answer about the contribution of germline UNC5C mutations to genetically unexplained hereditary CRC and/or polyposis cases. To achieve this goal we sequenced the coding region and exon-intron boundaries of UNC5C in 544 familial CRC or polyposis patients (529 families), using a technique that combines pooled DNA amplification and massively parallel sequencing. A total of eight novel or rare variants, all missense, were identified in eight families. Co-segregation data in the families and association results in case-control series are not consistent with a causal effect for 7 of the 8 identified variants, including c.1882_1883delinsAA (p.A628K), previously described as a disease-causing mutation. One variant, c.2210G > A (p.S737N), remained unclassified. In conclusion, our results suggest that the contribution of germline mutations in UNC5C to hereditary colorectal cancer and to polyposis cases is negligible. ; This work was funded by the Spanish Ministry of Economy and Competitiveness and co-funded by FEDER funds -a way to build Europe- [SAF2012-38885 (LV), SAF2013-45836-R (XSP), SAF2012-33636 (GC)]; Carlos III Health Institute [PI13-00285 (CL), PI11-01439 (VM)]; Red Tematica de Investigacion Cooperativa en Cancer [RTICC RD12/0036/0031, RD12/0036/0008, RD12/0036/0067], the Government of Catalonia [2014SGR338, 2014SGR647], and the Scientific Foundation Asociacion Espanola Contra el Cancer. We thank Tirso Pons from the Spanish National Cancer Research Center (CNIO) for his assistance. We are grateful to the researchers of the MCC-Spain study for providing the data to assess the identified UNC5C rare variants in the general population. ; Sí