The BRCA1 exon 13 duplication: clinical characteristics of 22 families in Northern Sweden.

The clinical management of BRCA1/2 mutation carriers requires accurate cancer risk estimates. Cancer risks vary according to type and location of the mutation and since there is limited information about mutation-specific cancer risks, genotype-phenotype correlation studies are needed. This is a report of 22 families with the same mutation, BRCA1 duplication exon 13, a mutation that is found world-wide, with the objective to describe the cancer history found in these families. We studied 69 confirmed carriers, 53 women and 16 men, and additionally 29 women who were clinically expected carriers. Among the confirmed carriers, 27 women (51%) were diagnosed with breast cancer, 10 (19%) with ovarian cancer, 5 (9%) with breast and ovarian cancer and 17 (32%) without cancer. Nine women (17%) with breast cancer were 35 years or younger at diagnose. Also, two cases of early onset colon cancer were found, and 37,5% of the male carriers were diagnosed with prostate cancer. These data may have implications for risk assessment and cancer prevention decision making for carriers of the BRCA1 duplication exon 13 mutation.