Mutational analysis of BRCA1 and BRCA2 genes in women with familial breast cancer from different regions of Colombia.

PURPOSE

The main risk factor for familial breast cancer is the presence of mutations in BRCA1 and BRCA2 genes. The prevalence of mutations in these genes is heterogeneous and varies according to geographical origin of studied families. In Colombia mutations in these genes have been mainly studied on patients from Andean region. Bogotá and Medellin presented its own battery of mutations. This study aims to identify mutations in BRCA1-2 genes in women with familial breast cancer from different regions of Colombia.

METHODS

One hundred four families with a history of breast cancer were sampled in different regions of Colombia, and the BRCA1 gene and exon 11 of the BRCA2 gene were sequenced. To predict the possible effects of sequence alterations found in protein function, different bioinformatics tools were used.

RESULTS

A total of 33 variants were found; 18 in BRCA1 and 15 in BRCA2, of which 15 are unique variants of Colombia. In silico analysis established that alterations p.Thr790Ala, p.Arg959Lys and p.Glu1345Lys in the BRCA1 gene and variants p.Leu771Phe, p.Asn818Lys, p.Val859Ser*22 and p.Lys1032Ile in the BRCA2 gene are considered likely pathogenic. Both the mutations as the variants of unknown clinical significance, in their great majority, presented a specific region distribution and they were different from those reported in previous studies.

CONCLUSIONS

In this study we report the BRCA1 and BRCA2 spectrum of mutations and their distribution by regions in Colombia. Our results may help to design a diagnostic test including recurrent mutations for screening high risk to breast cancer families in Colombia.