Ethylmalonic Encephalopathy

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This disorder is caused by a problem in the ETHE1 gene. The gene produces the ETHE1 enzyme, which helps to break down sulphide. This process is needed because sulphide helps to maintain normal cell functioning across the body. 

 If you have a problem in the ETHE1 gene, you will not produce enough of the ETHE1 enzyme. Therefore, you will be unable to break down sulphide and this causes a build-up in your system, which is toxic at high levels and can stop your cells from functioning properly. 

Ethylmalonic Encephalopathy is an extremely rare disorder, and only around 70 cases have been diagnosed worldwide. It appears to be more prevalent in Mediterranean and Arab populations.  

The symptoms of Ethylmalonic Encephalopathy typically appear from birth, or within the first few months of life. This disorder predominantly affects the functioning of your brain, digestive system, and circulation (specifically blood vessels).  

Symptoms get increasingly worse over time and include: 

• Delayed development 
• Loss of skills (developmental regression) 
• Weak muscle tone (hypotonia) 
• Seizures 
• Abnormal movements 
• Rash of red spots caused by bleeding under the skin due to weak blood vessels (petechiae) 
• Reduced oxygen circulation, causing a blue tinge to hands and feet (acrocyanosis) 
• Chronic diarrhoea 

 Life expectancy is short, and most children do not live beyond 10 years old. 

Your medical team will use specialised blood and urine tests to diagnose the disorder. They may also complete a genetic test. Sometimes an MRI scan of your brain is required. 

 Some cases of Ethylmalonic Encephalopathy are first diagnosed as a different neurological disorder, such as multiple acyl-CoA dehydrogenase deficiency (MADD) or short chain acyl-CoA dehydrogenase deficiency (SCADD). 

 Due to its tendency to be misdiagnosed, Ethylmalonic Encephalopathy may actually be under-diagnosed. There may, in fact, be more cases worldwide than we currently know. 

 Currently, newborn screening in the UK does not include Ethylmalonic Encephalopathy. However, it is available as part of the standard newborn screening process in some parts of the USA.  

There is currently no cure for Ethylmalonic Encephalopathy. However, there has been some success with supplement treatment to reduce the amount of sulphide in your body. This can help to reduce the severity of some symptoms and delay the onset of any serious health issues. This treatment is most effective when it is commenced early in life, so getting a quick diagnosis is important. 

 Your medical team will also offer you specialised dietary support, which is important to reduce the risks associated with dehydration and nutrition deficiency that may be caused by chronic diarrhoea. As well as this, you may be offered physical, speech, and occupational therapies. 

The prognosis for this disorder is poor. Most children do not live beyond 10 years old. 

Ethylmalonic Encephalopathy is inherited from both parents in an autosomal recessive inheritance pattern. This means that both parents are carriers of the disorder through their genes.  

All genes come in pairs. Carriers of Ethylmalonic Encephalopathy have one working ETHE1 gene and one faulty gene. Children inherit one gene from each parent to make their pair. Whether you have Ethylmalonic Encephalopathy depends on the genes you inherit: 

 There is a 50% chance that the child will inherit one faulty and one working gene, which means they will also be a carrier. 

• There is a 25% chance that the child will inherit two working genes and not inherit or carry the faulty gene. 
• There is a 25% chance that the child will inherit two faulty genes, which means they will have Ethylmalonic Encephalopathy. 

 If you think you, or somebody in your family, may have Ethylmalonic Encephalopathy, or that you may be a carrier, contact your medical team who may refer you for genetic testing. 

References are available on request. Please contact us by phoning 0845 241 2173 or emailing contact@metabolicsupportuk.org [Resource Library No: EEM043].