For instance, accumulation of hydrogen sulfide in patients with ethylmalonic encephalopathy (a disease caused by mutations in the ethylmalonic encephalopathy protein 1 (ETHE1) gene coding for a sulfur dioxygenase) may be reduced by the combined application of N-acetylcysteine and metronidazole [117,118,119]. This evidence concerns the gene ETHE1 and ethylmalonic encephalopathy.