Abstract

               Ethylmalonic encephalopathy (EE) is a rare metabolic disorder caused by dysfunction of ETHE1 protein, a mitochondrial dioxygenase involved in hydrogen sulfide (H2S) detoxification. EE is usually a fatal disease with a severe clinical course mainly associated with developmental delay and regression, recurrent petechiae and chronic diarrhoea. Clinical symptoms may present from birth or several months after birth. Treatment includes antioxidants, antibiotics that reduce H2S level and antispastic medications, which are not curative. The mutations causing absence of the ETHE1 protein, as in the case for the described patient, usually entail a severe fatal phenotype. Although a few rare cases mild clinical findings were reported, the mechanism resulting in these milder cases is also unclear. In this article, we describe a 5-year-old boy with a mutation in the ETHE1 gene, with chronic diarrhea, microscopic hematuria, motor and language retardation, who is on a “low methionine and cysteine” diet and in consideration of changing into oral medications.