[Mutations in the BRCA1 gene in young Spanish women with breast cancer]. / Mutaciones en el gen BRCA1 en mujeres españolas jóvenes con cáncer de mama.

BACKGROUND: Germline mutations in the BRCA1 gene have been associated with familial breast/ovarian cancer. Furthermore, women diagnosed of early-onset breast cancer have a higher probability of being carriers of BRCA1 mutations. Our aim was to know prevalence of BRCA1 mutations in women with breast cancer diagnosed before 40 years. PATIENTS AND METHODS: We analyzed genomic DNA samples of 159 women with early-onset breast cancer. Ten fragments of BRCA1 gene covering the 36% of cases with mutations described in the literature were screened. Analysis involved polymerase chain reaction (PCR), single-strand conformation polymorphisms (SSCP) and direct sequencing. RESULTS: Three germline BRCA1 mutations were identified, one of them not previously described. Two mutations were found in women with familial history of breast cancer. Five additional rare variants and polymorphisms were also detected. CONCLUSIONS: The absence of recurrent mutations or mutations detected in other countries, except for the 185delAG mutation, present in Ashkenazim population, shows the influence of ethnic and geographic origin of population studied, and illustrates the difficulties of establishing DNA-based screening tests for hereditary breast cancer.