Among the less-frequently studied markers, HE4 showed high specificity though with limited sensitivity, ATX was associated with advanced-stage ovarian cancer and reduced disease-free survival, with one study reporting an AUC of 0.842 [18], while a microRNA ratio (miR-21/miR-223) achieved an AUC of 0.982 for differentiating malignant from non-malignant ascites [38]. The gene discussed is ENPP2; the disease is ovarian cancer.