BRCA1 and BRCA2 germline mutations contribute to a significant number (10-15%) of familial and hereditary breast and/or ovarian cancers. The proportion of high-risk families with breast and/or ovarian cancer cases due to mutations in these tumor suppressor genes varies widely among populations.

In some population, a wide spectrum of different mutations in both genes are present, whereas in other groups specific mutations in BRCA1 and BRCA2 have been reported with high frequency. Most of these mutations are prevalent in restricted populations as a consequence of a founder effect.

The comparison of specific genetic units called haplotypes between families with the same mutation can distinguish whether high-frequency alleles derive from an older or more recent single mutational event or whether they have arisen independently more than once.

The identification of the presence of founder mutation in families undergoing genetic counseling enables the geneticist and oncologist to make more specific choices, leading to simplify the clinical approach to genetic testing carried out on members of high-risk families. Furthermore, the high frequency of founder mutations allows the laboratory scientists to analyze a large number of cases, with lower cost and this information will eventually provide accurate information for the genetic counselling and medical treatment.