Ethylmalonic encephalopathy
OMIM number: 602473
Comments closing date: 13/07/2026
Ethylmalonic encephalopathy is a rare hereditary (genetic) condition which affects the nervous
system, blood vessels, and other parts of the body. It is caused when a person is born with
mutations (also called “pathogenic variants”) in both of their ETHE1 genes. When the ETHE1
gene is working, it produces an enzyme which breaks down a molecule called sulfide. If someone
has Ethylmalonic encephalopathy, they cannot break down sulfide, which builds up in the body.
This can damage the brain, muscles, blood vessels, and intestines, leading to the symptoms
of the condition. Sadly, this condition is very lifelimiting,and babies usually do not survive past
early childhood. Symptoms include failing to achieve developmental milestones, low muscle
tone, seizures, bleeding under the skin, and chronic diarrhoea. If two carriers of this condition
conceive together, there is a 1 in 4 (25%) chance of passing it on at each conception. There is no
cure for the condition, but affected babies are made as comfortable as possible before passing.
