Paired analysis of tumour-derived versus blood-derived DNA to determine the prevalence of deleterious somatic variants in OC predisposition genes (<i>ATM</i>, <i>BRCA1/2, BRIP1</i>, <i>MSH2/6</i>, <i>PALB2</i>, <i>RAD51C/D</i> and <i>TP53</i>) and the <i>PIK3CA</i> and <i>PTEN</i> genes in individuals with OC (AGO-TR1 study, NCT02222883).
There is ongoing debate whether pathogenic RAD51C alterations increase the relative risk for BC in addition to that for OC, which was estimated to be 5.88 (95% confidence interval = 2.91 to 11.88; P = 7.65 × 10(-7)).
The rare finding of a clearly truncating RAD51C mutation in an early-onset BC patient with a BC-only family history supports the notion that compromised RAD51C function may result in both BC and OC.
These results confirm that RAD51C and RAD51D are moderate ovarian cancer susceptibility genes and suggest that they confer levels of risk of EOC that may warrant their use alongside BRCA1 and BRCA2 in routine clinical genetic testing.
Deleterious mutations in the RAD51C gene, which encodes a DNA double-strand break repair protein, have been reported to confer high-penetrance susceptibility to both breast and ovarian cancer.
Population-based BRCA1/BRCA2/RAD51C/RAD51D/BRIP1/PALB2 testing can prevent 1.86%/1.91% of BC and 3.2%/4.88% of OC in UK/US women: 657/655 OC cases and 2420/2386 BC cases prevented per million.
An increased cancer risk has been firmly established for carriers of mutations in FANCD1/BRCA2, FANCJ/BRIP1, FANCN/PALB2, RAD51C/FANCO and link the FA pathway to inherited breast and ovarian cancer.
We evaluated homologous recombination deficient (HRD) phenotypes in epithelial ovarian cancer (EOC) considering BRCA1, BRCA2, and RAD51C in a large well-annotated patient set.
Deleterious and missense mutations of RAD51C have recently been suggested to modulate the individual susceptibility to hereditary breast and ovarian cancer and unselected ovarian cancer, but not unselected breast cancer (BrC).
In the Finnish population, we have identified two founder mutations in RAD51C that increase the risk of ovarian cancer but not breast cancer in the absence of ovarian cancer.
Our results support that RAD51C is a rare breast and ovarian cancer susceptibility gene and may contribute to a small fraction of families including breast and ovarian cancer cases and families with only breast cancer.
RAD51Cc.-13_14del27 was observed in one familial breast cancer case and c.774delT in one unselected ovarian cancer case, thus confirming that RAD51C mutations are implicated in breast and ovarian cancer predisposition, although their overall frequency seems to be low.
In index cases from 1,100 German families with gynecological malignancies, we identified six monoallelic pathogenic mutations in RAD51C that confer an increased risk for breast and ovarian cancer.
Although the cumulative frequency of RAD51C and RAD51D truncating mutations in our patients was lower than that of the BRCA1 and BRCA2 genes, it may explain OC susceptibility in approximately 3% of high-risk OC patients.
We have screened RAD51C sequence variants by HRMA in 492 breast cancer patients with family history of breast and/or ovarian cancer that were previously tested negative for BRCA1/2.
The analysis also showed a substantial difference in the profile of genes contributing to either BC or OC risk, including genes specifically associated with a high risk of OC but not BC (e.g., RAD51C, and RAD51D).