In a recent metaanalysis of 19 studies evaluating the predictive value of cystatin in diagnosing AKI in mixed ICU population (cardiac surgery, pediatric, and critically ill), serum cystatin C appeared to be a good biomarker in the prediction of AKI, whereas urinary cystatin C excretion had only moderate diagnostic value [83]. The gene discussed is CST4; the disease is acute kidney injury.