NOS2 and asthma: In a study of the relationships among the expressions of NO-related enzymes (i.e., iNOS2 and ARG2), asthma severity, FeNO, and eosinophilic inflammation, the index of iNOS to ARG2 mRNA was reported to be a valuable marker to differentiate severe from milder asthma, despite a tendency for ARG2 mRNA levels to decrease with asthma severity [76].