Receiver operating characteristic (ROC) curve analysis established a cutoff value of >9.4 mg/L for serum cystatin C as a diagnostic marker for AKI, with 88.46% sensitivity, 75% specificity, 79.3% positive predictive value, and an 85.7% negative predictive value at an area under the curve (AUC) of 0.848 (Table 7, Figure 4). The gene discussed is CST3; the disease is acute kidney injury.