In addition, CSE catalyzes the formation of the products lanthionine and homolanthionine from substrate combinations Cys/Cys and Hcy/Hcy, respectively, both of which produce H2S. Thioether metabolites lanthionine and homolanthionine have been proposed as biomarkers of hydrogen sulfide generation in patients with CBS deficiency [73]. The gene discussed is CBS; the disease is hyperinsulinemic hypoglycemia, familial, 4.