A high prevalence of BRCA1 mutations among breast cancer patients from the Bahamas

Sylvester Comprehensive Cancer Center, University of Miami, Miami, FL, USA.
Breast Cancer Research and Treatment (Impact Factor: 3.94). 01/2011; 125(2):591-6. DOI: 10.1007/s10549-010-1156-9
Source: PubMed


The Bahamas is a group of islands in the Caribbean with a high incidence of early onset breast cancer. In isolated populations, the identification of founder mutations in cancer predisposing genes may facilitate genetic testing and counseling. To date, six distinct BRCA1 mutations have been found in patients from cancer families from the Bahamas. The frequencies of these mutant alleles have not been measured in a large series of unselected breast cancer patients from Bahamas. We studied 214 Bahamian women with invasive breast cancer, unselected for age or family history of cancer. All patients were screened for six mutations in the BRCA1 gene that have previously been reported in cancer patients from the Bahamas. A mutation was identified in 49 of the 214 breast cancer patients (23%). The mutation frequency was particularly high in women diagnosed before age 50 (33%) in women with a first-degree relative with breast or ovarian cancer (41%) and in women with bilateral breast cancer (58%). Approximately 23% of unselected cases of breast cancer in the Bahamian population are attributable to a founder mutation in the BRCA1 gene-this is the highest reported mutation prevalence for any country studied to date. Genetic testing for these mutations is advisable for all women diagnosed with breast cancer in the Bahamas.

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    • "Genetic testing could be made accessible to women in developing countries if common BRCA founder mutations in the two genes can be discovered or if the cost of genetic testing is reduced. Populations with a large proportion of genetically associated cancers attributable to founder mutations include the Ashkenazi Jewish [12,13], Bahamian [14], Polish [15], Mexican American [16-18], and French-Canadians [19]. The presence of founder effects within these ethnic groups has enabled rapid and low cost screening compared to the cost of complete sequencing of both BRCA genes [20]. "
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    ABSTRACT: Approximately 5% of all breast cancers can be attributed to a mutation in the BRCA1 or BRCA2 gene. The genetic component of breast cancer in Colombia has been, for the most part, studied on cases from the Bogota region. Five different founder mutations were in two studies of breast cancer patients in the Bogota region. It is important that the frequency of mutations be established among unselected cases of breast cancer of other regions of Colombia in order to estimate the genetic burden of this cancer in Colombia and to plan genetic services. The aim of this study was to establish the mutation frequencies of the BRCA genes in breast cancer patients unselected for family history or age, from Medellin, Colombia. We enrolled 280 unselected women with breast cancer from a large public hospital in Medellin, Colombia. A detailed family history from each patient and a blood sample was obtained and processed for DNA analysis. Mutations in BRCA1 and BRCA2 were sought using a combination of techniques including a panel of recurrent Hispanic BRCA mutations which consists of fifty BRCA1 mutations and forty-six BRCA2 mutations, including the five recurrent Colombian BRCA mutations. All mutations were confirmed by direct sequencing. Genetic testing was successfully completed for 244 of the 280 cases (87%). Among the 244 cases, three deleterious mutations were identified (two in BRCA1 and one in BRCA2) representing 1.2% of the total. The average age of breast cancer in the mutation-positive cases was 34 years. The two BRCA1 mutations were known founder mutations (3450del4 in exon 11 and A1708E in exon 18). The BRCA2 mutation was in exon 11 (5844del5) and has not been previously reported in individuals of Colombian descent. Among the three mutation-positive families was a breast cancer family and two families with no history of breast or ovarian cancer. The frequency of BRCA mutations in unselected breast cancer cases from the Medellin region of Colombia is low and is approximately 1.2%.
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    ABSTRACT: Genetic testing for BRCA1 and BRCA2 mutations is gaining acceptance in clinical oncology worldwide and may help target unaffected high-risk women for prevention and for close surveillance. Annual screening with MRI seems to be an effective surveillance strategy, but the long term follow-up of women with small MRI-detected breast cancers is necessary to establish its ultimate value. Women with cancer and a BRCA mutation may benefit from tailored treatments, such as cisplatin or olaparib. The treatment goals for a woman with a BRCA-associated breast cancer should be to prevent recurrence of the initial cancer and to prevent second primary breast and ovarian cancers. Mutations in BRCA1 and BRCA2 are presented throughout the world and it is important that the benefits of genetic testing and of targeted therapies be extended to women who live outside of North America and Western Europe.
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