BRCA2 alteration is important in clear cell carcinoma of the ovary

BRCA2 has been shown to play a significant role in hereditary ovarian carcinoma. Several cases of clear cell carcinoma (CCC) of the ovary containing BRCA2 mutations have been identified. We hypothesize that sequence variants of the BRCA2 gene are common in CCC of the ovary. Multiple methods were utilized to detect BRCA2 genetic alterations in a cohort of 13 ovarian CCC. These included an LOH analysis for copy number, real-time and methylation-specific polymerase chain reaction (PCR) to probe for BRCA2 promoter methylation, in addition to protein truncation testing (PTT) gel screening for nonsense BRCA2 mutations, and finally direct gene sequencing to either confirm the nonsense mutations or to detect candidate missense mutations in the remaining tumor samples. Whenever a sequence variation was detected in a tumor sample, the corresponding region was sequenced from a blood sample to determine germline status. Seven BRCA2 sequence variations were identified in 6 of the 13 CCC (46%); three tumors contained an alteration in BRCA2 copy number. Only one subject carried a germline sequence variation that might alter BRCA2 function despite the fact that a family history of breast, ovarian or colon cancer was common in this population. The 5-year disease-specific survival probability for patients with a BRCA2 alteration is 87.5%, compared to only 40% for those patients without a BRCA2 alteration (p = 0.39). Alterations in BRCA2 gene sequence, copy number, or expression are extremely common in CCC and may contribute to a paradoxical better clinical outcome.