Analysis Of Genomic Ancestry In A Sample Of High-Risk Patients With Hereditary Breast Cancer From Bahia, Brazil.

1515 Background: Many diseases, including cancer, have prevalence related to race and/or to ethnics or geographics aspects. Admixture mapping has been done in several populations including Brazilian people. Muniz et al (2008) observed an ancestry of 62% European, 26% African and 12% Natives in Brazilian afrodescendents. According to IBGE (Brazilian Institut of Geography and Statistic) data the people from Bahia is predominantely made by afrodescendent (77,5%) but this information is based on pheonotype analysis. There is no information about the association between this admixture and hereditary breast/ovary cancer (HBOC) in patients from Bahia- Brazil. The primary objective of this work is to study the genomic ancestry of HBOC high risk patients from Bahia’s (Brazil) ethnically diverse population. Methods: Charts of 109 patients referred to the Oncogenetics Service were reviewed and the blood samples were collected and submitted to molecular studies for the following ancestry informative markers (AIMs): AT3-I / D, PDB SB19.3, PV92, FY-null, LPL, CKMM, GC1S and GC-1F. Admixture mapping was analyzed using the program ADMIX. Results: Ancestry as reported by the patients: 49% referred “Brazilian” (they do not know to specify); 38% referred European and only 5.5% reported African ancestries. Genomic ancestry analysis showed the following contribuition: 66% of European and 34% of African. South American natives contribuition it was not detected in this sample. Conclusions: The genomic ancestry analysis shows a high European contribuition which agrees with the literature that reports a higher prevalence of breast cancer among Caucasian women. So, although the Bahia’s population has a well known large African ancestry, the sample of HBOC high risk patients studied has a larger European than African ancestry contribuition.