ARID1A and ovarian cancer: In particular, the real precursor of ovarian cancer is represented by atypical endometriosis which is seen in 60–80% of ovarian cancers that result from endometriosis [2,4].In addition, the most common mutations in atypical endometriosis affect ARID1A, PIK3CA, genes coding for estrogen and progestogen receptors, KRAS and PTEN [2].