The enhanced production of ROS causes endothelial dysfunction thus leading to atherosclerosis (Fig. 3).57 Moreover, it has also been reported that CYP1B1 contributes in the development of pulmonary arterial hypertension (PAH), a progressive disease of the pulmonary vasculature resulting in right heart failure and death. The gene discussed is CYP1B1; the disease is pulmonary arterial hypertension.