Although the Greek population is characterized by genetic heterogeneity, our extensive 15–year research on hereditary breast/ovarian cancer has highlighted the existence of 6 recurrent mutations including four founder (c.5266dupC, p.G1738R, delex20,delex24) accounting for 63% of all mutations identified in BRCA1/2 genes and 73% of mutations identified in BRCA1 only [17]–[21]. The gene discussed is BRCA1; the disease is ovarian cancer.