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Keywords:

  • BRCA1;
  • BRCA2;
  • genetic testing;
  • pedigree analysis

Thousands of individuals have undergone mutational analysis of BRCA1 and BRCA2. The Ohio State University Clinical Cancer Genetics program has identified 466 individuals from 289 families with a mutation in BRCA1 or BRCA2. Excluding Ashkenazi Jewish founder mutations, we observed 9 deleterious BRCA mutations five or more times in ostensibly unrelated families and another 13 mutations in 3–4 families. We hypothesized that some of the rarer recurrent mutations observed in our population were due to different branches of the same family being tested independently without knowledge of previous testing of relatives. We examined 90 pedigrees for individuals with the same mutations that were seen three or more times for shared reported family medical history or surnames. Familial links were made in four instances out of a total of 22 shared mutations despite the fact that individuals were not aware that another family member had been tested. As more individuals undergo BRCA testing, we propose that this phenomenon will become more common. Being unaware of previous testing in a family not only affects the risk assessment but also likely increases the costs associated with the genetic testing and subsequent cancer screening in many cases.