ETHE1 and ethylmalonic encephalopathy: While elevated H2S levels have been implicated in the pathogenesis of multiple CNS diseases — including schizophrenia and amyotrophic lateral sclerosis [[240], [241], [242]] — perhaps the best example is ETHE1 deficiency, a rare, severe disease where an inactivating mutation in ETHE1 protein severely impairs the patients cells' ability to detoxify H2S. This rare autosomal recessive condition is known as ethylmalonic encephalopathy.