Recent work by Crabtree and coworkers even described an interplay of BH4 deficiency and eNOS S-glutathionylation in cells with diminished GTP-cyclohydrolase-1 expression providing a functional link between these two routes of eNOS uncoupling [120] that could be of relevance for the aging process as well. The gene discussed is NOS3; the disease is hyperinsulinemic hypoglycemia, familial, 4.