SOD2 and pulmonary arterial hypertension: For example, reduced expression of SOD2 in the fawn hooded rat (FHR) is thought to underlie the development of PH [89] and in human PAH, reduced SOD2 expression is also seen in hypertensive PAs as well as in plexiform lesions [53,85] and polymorphisms in the SOD2 gene can increase the risk of PAH [90].