Ethylmalonic encephalopathy (EE) is a devastating infantile metabolic disorder that affects multiple body systems including the brain, gastrointestinal tract and blood vessels. It is caused by a defective enzyme that plays a part in production of energy for the body. Symptoms may include developmental delay, psychomotor regression, low muscle tone, abnormal movements of the arms and legs, seizures, skin rash, blue discoloration of the hands and feet and chronic diarrhea. Symptoms can be apparent at birth or appear within the first few months of life. Functions of the nervous system progressively worsen and most affected individuals only survive to early childhood. There is no cure for EE; however medical surveillance and care may help to improve some symptoms and overall condition of life. EE is caused by pathogenic variants in the ETHE1 gene.