ARID1A mutations, including missense, nonsense and frame shift mutations led by small insertion and deletion, have frequently been detected in a series of human tumors, including ovarian clear-cell carcinoma [1, 2], gastric cancer [3, 4], breast cancer [3, 5, 6], pancreatic cancer [3, 7, 8], cholangiocarcinoma [9, 10], clear cell renal cell carcinoma [11], esophageal adenocarcinoma [12], neuroblastoma [13], diffuse large B-cell lymphoma [14] and transitional cell carcinoma of the bladder [15]. The gene discussed is ARID1A; the disease is gastric cancer.