Various factors could explain the difference in potency between NO and CO in inducing migraines: (1) NO has a greater potent effect on cGMP activation compared to CO [104], (2) CO’s strong binding to hemoglobin results in a small amount of free CO available for linking to sGC, and (3) the limitation on using higher concentrations of CO due to its toxicity. The gene discussed is SGCB; the disease is migraine disorder.