Among these, the AT-interacting domain-rich protein 1A (ARID1A), an accessory subunit, contains mutations in ∼50% of ovarian clear cell carcinoma cases, as well as in gastric cancer (∼20%), bladder cancer (∼20%), liver cancer (∼15%), colorectal cancer, and breast cancer [4–7]. The gene discussed is ARID1A; the disease is gastric cancer.