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Abstract P2-11-02: Mapping Mutations: Importance of Family Geographic Origin in Portuguese High-Risk Breast/Ovarian Cancer Families for BRCA Mutation Screening

2010; American Association for Cancer Research; Volume: 70; Issue: 24_Supplement Linguagem: Inglês

10.1158/0008-5472.sabcs10-p2-11-02

1538-7445

Sofia Fragoso, Patrícia Maria Abreu Machado, S. Santos, Paulo Rodrigues, Joana Parreira, S. Bento, A. Luís, Fátima Vaz,

Genetics, Bioinformatics, and Biomedical Research

Abstract Background: Hereditary breast/ovarian cancer is mainly related with BRCA1/2 mutations. The complete screening of both genes is long and expensive due to their large number of exons and the inexistence of hotspots. Besides our most frequent BRCA mutation, c.156_157insAlu in BRCA2, the Portuguese population has many other mutations in these genes, described over the years. Aim: to evaluate the importance of screening specific mutations, found in BRCA positive families, in other probands with the same geographic origin. Patients and methods: 407 high risk breast/ovarian cancer patients were screened for c.156_157insAlu in BRCA2 (the Portuguese founder mutation), BRCA1/2 point mutations and large rearrangements. All probands were questioned about their family origin. Mutations detected in families were studied in new probands with the same geographic origin. Results: we were able to draw a map with the geographic origin of our 87 BRCA positive families. Most of our BRCA families have origin in the centre of Portugal. While searching probands with the same geographic origin as others previously detected, we found three additional mutations without screening the whole genes: 1 family from Madeira island; 1 family from the south (Algarve) and 1 non-affected individual, without previous family testing, that was positive for c.156_157insAlu in BRCA2 (her family had origin in an area of high prevalence of this mutation). Our maps also allowed the linking of several families with the same mutation and family origin, but apparently unrelated. Conclusion: Mapping geographic origin of BRCA1/2 mutations may help in the quick identification of new BRCA1/2 carriers and, in some cases, reduce the screening time. Most importantly it permits the linking of apparently unrelated families. This link permits a more accurate estimation of BRCA1/2 positive families and a better understanding of all at-risk family members. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-11-02.