Here, we report the frequency of the 999del5BRCA2 mutation in an Icelandic control population and four different groups of cancer patients diagnosed with (a) breast cancer; (b) ovarian cancer; (c) prostate cancer (patients younger than 65 years); and (d) other cancer types.
Germline mutations of BRCA2 are predicted to account for approximately 35% of families with multiple case, early onset female breast cancer, and they are also associated with an increased risk of male breast cancer, ovarian cancer, prostate cancer and pancreatic cancer.
Germline mutations of BRCA1 are also associated with ovarian cancer and mutations of BRCA2 are associated with an increased risk of male breast cancer, ovarian cancer, prostate cancer and pancreatic cancer.
The risk ratio of prostate cancer was 4.6 (1.9-8.8) in first-degree relatives and 2.5 (1.2-4.6) in second-degree relatives of the 16 BRCA2 positive breast cancer probands.
Genes underlying these cancers are now recognized in colorectal cancer (APC, mismatch repair genes, LKB1) and in breast cancer (BRCA1, BRCA2) whereas, in prostate cancer, a locus in chromosome 1 (HPC1) has been proposed on the basis of linkage analysis.
We tested for the BRCA1 185delAG frameshift mutation, found in 0.9% of Ashkenazi Jews, and the BRCA26174delT mutation, found in 1% of Ashkenazi Jews, in Ashkenazi Jewish men with prostate cancer.
These data suggest that microsatellite instability and loss of unidentified genes on chromosome 8p may be involved in carcinogenesis of the prostate; however, BRCA1 and BRCA2 may not be largely involved in the development of prostate cancer in the Japanese population.
Two known tumor suppressor genes, RB1 and BRCA2, map to chromosome 13; however, recent reports suggest that unknown genes on 13q are more likely to be involved in the development of prostate cancer.
In this study, 22 high-risk prostate cancer families (at least three cases of prostate cancer) were screened by conformation-sensitive gel electrophoresis (CSGE) for mutations in BRCA1 and BRCA2.
Blood DNA from affected individuals in 38 prostate cancer clusters was analyzed for germ-line mutations in BRCA1 and BRCA2 to assess the contribution of each of these genes to familial prostate cancer.
Germline mutations of BRCA1 and BRCA2 predispose to hereditary breast, ovarian, and possibly prostate cancer, yet structural mutations in these genes are infrequent in sporadic cancer cases.
Although BRCA2 is probably responsible only for a very small fraction of hereditary prostate cancers, this finding supports previous reports of an increased risk of prostate cancer in BRCA2 mutation carriers.
A second breast cancer susceptibility gene (BRCA2) operates in some of the same molecular pathways as BRCA1, and mutations of this gene predispose to breast and ovarian cancer and probably to other tumor types, including prostate cancer.
Early age at diagnosis of breast cancer, ovarian cancer, bilateral breast cancer, concomitant breast/ovarian cancer in a single patient and prostate cancer but not unilateral breast cancer were associated with BRCA1 and BRCA2 mutations.
Our results suggest that BRCA2 mutations alone are inadequate to explain all of the excess clustering of prostate cancer cases in families of breast cancer probands, and that additional genes conferring excess risk to both breast and prostate cancer may exist in this population.
These results confirm that BRCA2 is a high-risk prostate-cancer-susceptibility gene and have potential implications for the management of early-onset prostate cancer, in both patients and their relatives.