In summary, our results on the entire Sardinian population demonstrated that: a) prevalence of BRCA1 and BRCA2 mutations is 10% in familial breast-ovarian cancer; b) the spectrum of mutations among Sardinians is unique; c) some specific phenotypic features may be predictive for the presence of BRCA1-2 germline mutations and should be therefore considered when counselling Sardinian patients about undergoing genetic testing. This evidence concerns the gene BRCA1 and Hereditary breast and ovarian cancer syndrome.