Portuguese c.156_157insAlu BRCA2 founder mutation: gastrointestinal and tongue neoplasias may be part of the phenotype

We have screened BRCA2 c.156_157insAlu founder mutation in a cohort of 168 women with diagnosis of breast cancer referred for genetic counseling because of risk of being carriers of hereditary breast and ovarian cancer syndrome. Portuguese founder mutation BRCA2 c.156_157insAlu was identified in three unrelated breast cancer probands. Genotyping identified a common haplotype between markers D13S260 and D13S171, and allele sizes were compatible to those described in the Portuguese families. Allele sizes of marker D13S1246, however, were concordant in two families, suggesting that the haplotype may be larger in a subset of families. Tumor phenotypes in Brazilian families seem to reinforce the high prevalence of breast cancer among affected males. However, an apparent excess of gastrointestinal and tongue neoplasias were also observed in these families. Although these tumors are not part of the phenotypic spectrum of hereditary breast and ovarian cancer syndrome, they might be accounted for by other risk alleles contained in the founder haplotype region.