Secondary outcomes included acute kidney injury (AKI), receipt of renal replacement therapy (RRT), duration of mechanical ventilation, length of intensive care unit stay, length of hospital stay, receipt of extracorporeal membrane oxygenation (ECMO), mean pulmonary artery pressure, partial pressure of arterial oxygen/fraction of inspiratory oxygen (PaO<sub>2</sub>/FiO<sub>2</sub>) ratio, elevated methemoglobin concentrations (> 5%), elevated nitrogen dioxide concentrations (> 3 ppm), extubation, and reintubation. The gene discussed is HBG2; the disease is acute kidney injury.