Combined treatment with oral metronidazole and N-acetylcysteine is effective in ethylmalonic encephalopathy.

Ethylmalonic encephalopathy is caused by mutations in ETHE1, a mitochondrial matrix sulfur dioxygenase, leading to failure to detoxify sulfide, a product of intestinal anaerobes and, in trace amounts, tissues. Metronidazole, a bactericide, or N-acetylcysteine, a precursor of sulfide-buffering glutathione, substantially prolonged the lifespan of Ethe1-deficient mice, with the combined treatment being additive. The same dual treatment caused marked clinical improvement in five affected children, with hardly any adverse or side effects.