On the other hand, reduced NO production is a well-recognized marker of endothelial dysfunction and aging, which could originate from decrease eNOS expression, decrease availability of NO precursor (L-arginine), decrease availability in eNOS cofactor (BH4), and/or increase in endogenous NO inhibitor ADMA (Novella et al., 2012). The gene discussed is NOS3; the disease is endothelial dysfunction.