The area under the receiver operating characteristic (ROC) curve to identify the risk of cardiac death according to serum BDNF levels in patients with ChC was 0.74 (95% CI: 0.56-0.93) (Fig. 1) and the concentration of 2.5 ng/mL was the optimal cut point value, with 75% sensitivity and 70% specificity. The gene discussed is BDNF; the disease is cryohydrocytosis.