BRCA1 and breast cancer: In total, 5% of breast cancer cases are believed to be due to inherited genetic mutations (Lynch et al, 1984); 10–11.7% of ovarian cancer cases (Landis et al, 1999; Risch et al, 2001; Malanders et al, 2004) are believed to be the result of breast cancer susceptibility one and two (BRCA1/2) mutations (Miki et al, 1994; Wooster et al, 1995).