Mitochondrial Neurogastrointestinal Encephalomyopathy

Mitochondrial neurogastrointestinal encephalopathy (MNGIE) syndrome is a condition that mainly affects the digestive system and nervous system. Almost all people with MNGIE have gastrointestinal dysmotility, in which the muscles and nerves of the digestive system do not move food through the digestive tract efficiently and result in early satiety, nausea, dysphagia, gastroesophageal reflux, vomiting after eating (postprandial emesis), episodic abdominal pain and/or distention, and diarrhea . Affected people may also have cachexia, dropped eyelids or weakness of other muscles of the eyes, peripheral neuropathy (manifesting as tingling, numbness, and pain (paresthesias) symmetric weakness, that mainly affect the lower extremities) and hearing loss. Leukoencephalopathy, which is the deterioration of a type of brain tissue known as white matter, is a hallmark of MNGIE; however it does not usually cause symptoms in people with this disorder. MNGIE is caused by variations in the TYMP gene, important for allowing adequate levels of thymidine in the mitochondria. Inheritance is autosomal recessive. Diagnosis is confirmed by detecting the TYMP gene variations or the increased levels of thymidine and deoxyuridine in blood.

Genetic Mutations: Mitochondrial neurogastrointestinal encephalomyopathy is caused by genetic mutations, also known as pathogenic variants. Genetic mutations can be hereditary, when parents pass them down to their children, or they may occur randomly when cells are dividing. Genetic mutations may also result from contracted viruses, environmental factors, such as UV radiation from sunlight exposure, or a combination of any of these.

If you suspect you may have this disease, you may want to start collecting your family health history. Information such as other family members who have had similar symptoms, when their/your symptoms first appeared, or exposures to any potential disease-causing environmental factors should be discussed with your medical team.

Known Genetic Mutations: Mitochondrial neurogastrointestinal encephalomyopathy is caused by genetic mutations in the following known gene(s):

LIG3, TYMP, RRM2B, POLG

Given these known genetic mutation(s), you may want to ask your health care team if genetic testing is right for you. Genetic tests are laboratory tests that use samples of blood, saliva, or other tissues to help identify changes in genes, chromosomes, or proteins. Genetic testing can help confirm or rule out a suspected genetic disease, or can provide other useful information to your health care team.

Disruption in Metabolism: Mitochondrial neurogastrointestinal encephalomyopathy is caused by a disruption in a person’s metabolism. Metabolism is the series of chemical reactions in our body that turns the food we eat into energy and removes toxins. Hormones and specific proteins, called enzymes, help make the right chemical reactions happen in the right order. However, genetic changes can prevent hormones or enzymes from working properly, which can lead to a disruption in metabolism such as energy not being created for the body or toxins not being removed from the body.

Impaired Mitochondrial Function: Mitochondrial neurogastrointestinal encephalomyopathy is caused by an impairment, or issue, in mitochondrial function. Mitochondria make the energy needed for cells to work properly. When mitochondria are unable to produce enough energy for a cell, the cell can become damaged or can die. Depending on the location and number of damaged cells, different organs and body systems can be affected. 

Yes. It is possible for a biological parent to pass down genetic mutations that cause or increase the chances of getting this disease to their child. This is known as inheritance. Knowing whether other family members have previously had this disease, also known as family health history, can be very important information for your medical team.

There are multiple ways, or patterns, a disease can be inherited depending on the gene(s) involved. Based on GARD’s current data, this disease can be inherited in the following pattern(s):

Autosomal Recessive: Autosomal means the gene involved is located on one of the numbered chromosomes. Recessive means that a child must inherit two copies of the mutated gene, one from each biological parent, to be affected by the disease. A carrier is a person who only has one copy of the genetic mutation. A carrier usually doesn’t show any symptoms of the disease.

If both biological parents are carriers, there is a 25% chance their child inherits both copies of the mutated gene and is affected by the disease. Additionally, there is a 50% chance their child inherits only one copy of the mutated gene and is a carrier.