Dominant-negative pathogenic variant BRIP1 c.1045G>C is a high-risk allele for non-mucinous epithelial ovarian cancer: a case-control study

BRIP1 is a moderate susceptibility epithelial ovarian cancer (EOC) gene. Having identified the BRIP1 c.1045G>C missense variant in a number of families with EOC, we aimed to investigate the frequency of this and BRIP1.2392C>T pathogenic variant in patients with breast cancer (BC) and/or EOC. A case-control study of 3,767 cases and 2,043 controls was undertaken investigating the presence of these variants using Sanger sequencing and gene panel data. Individuals with BC and/or EOC were grouped by family history. BRIP1 c.1045G>C was associated with increased risk of BC/EOC (OR = 37.7; 95% CI 5.3-444.2; P=0.0001). The risk was highest for women with EOC (OR=140.8; 95% CI 23.5-1723.0; P<0.0001) and lower for BC (OR = 11.1; 95% CI 1.2-106.5; P=0.1588). BRIP1 c.2392C>T was associated with smaller risks for BC/EOC (OR=5.4; 95%CI 2.4-12.7; P=0.0003), EOC (OR=5.9; 95% CI 1.3-23.0; p=0.0550), and BC (OR=5.3; 95%CI 2.3-12.9; P=0.0009). Our study highlights the importance of BRIP1 as an EOC susceptibility gene, especially in familial EOC. The variant BRIP1 c.1045G>C, rs149364097, is of particular interest as its dominant-negative effect may confer a higher risk of EOC than that of the previously reported BRIP1 c.2392C>T nonsense variant. Dominant-negative missense variants may confer higher risks than their loss-of-function counterparts.