CYB5R3 and Schnyder corneal dystrophy: This study provides evidence that loss of CYB5R3 expression in adult male mouse cardiomyocytes causes SCD that is associated with Ca2+ mishandling, increased oxidative stress, decreased ATP production, and loss of redox regulation of myoglobin and CoQ, indicating that CYB5R3 is essential for maintaining cardiac redox equilibrium (Figure 9).