Examples include mutations in the ARID1A gene occurring in a subset of ovarian cancers (Jones et al., 2010) and breast cancers (Mamo et al., 2012) along with mutations in the MLL2, MLL3, SMARCD1, NCOR1 and ARID1B genes found in a subset of breast cancers (Stephens et al., 2012; Cancer Genome Atlas Network, 2012; Kandoth et al., 2013). Here, ARID1A is linked to breast cancer.