BRCA2 and breast cancer: However, several smaller studies examined these polymorphisms in BRCA1 and BRCA2 mutation carriers (Martin et al, 2003; Tommiska et al, 2005; Copson et al, 2006; Osorio et al, 2006; Wasielewski et al, 2007; Yarden et al, 2008), and some suggested an association between the TP53 Pro72 and the MDM2 309G alleles with an earlier age at breast cancer diagnosis (Martin et al, 2003; Tommiska et al, 2005; Osorio et al, 2006; Yarden et al, 2008).