Exome sequencing of affected duos and trios uncovers PRUNE2 as a novel prostate cancer predisposition gene

Background: Prostate cancer (PrCa) is one of the most hereditable human cancers, however, only a small fraction of patients has been shown to carry deleterious variants in known cancer predisposition genes.

Methods: Whole-exome sequencing was performed in multiple affected members of 45 PrCa families to select the best candidate genes behind part of the PrCa missing hereditability. Recurrently mutated genes were prioritised, and further investigated by targeted next-generation sequencing in the whole early-onset and/or familial PrCa series of 462 patients.

Results: PRUNE2 stood out from our analysis when also considering the available data on its association with PrCa development. Ten germline pathogenic/likely pathogenic variants in the PRUNE2 gene were identified in 13 patients. The most frequent variant was found in three unrelated patients and identical-by-descent analysis revealed that the haplotype associated with the variant is shared by all the variant carriers, supporting the existence of a common ancestor.

Discussion: This is the first report of pathogenic/likely pathogenic germline variants in PRUNE2 in PrCa patients, namely in those with early-onset/familial disease. Importantly, PRUNE2 was the most frequently mutated gene in the whole series, with a deleterious germline variant identified in 2.8% of the patients, representing a novel prostate cancer predisposition gene.