Seven studies with 1030 patients investigated the prognostic value of claudin-4 on the gastric cancer patients, and the pooled results showed that over-expression of claudin-4 was associated with a poor survival in gastric cancer patients (HR: 2.01, 95 % CI: 1.62–2.50, P < 0.001). The gene discussed is CLDN4; the disease is gastric cancer.