Mitochondrial neurogastrointestinal encephalopathy syndrome

What tests can be performed to diagnosis mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE)?

MNGIE can be diagnosed by measuring concentrations of thymidine and deoxyuridine in the blood. Elevated levels of plasma thymidine and deoxyuridine are sufficient to make the diagnosis. In addition, the activity of an enzyme called thymidine phosphorylase can be measured in white blood cells (leukocytes). If the activity of this enzyme is less than 10 percent of normal, the diagnosis of MNGIE is confirmed.

Genetic testing can also be performed for MNGIE, and it is typically used to identify unaffected carriers of the condition. First, a DNA sample from an affected individual is tested to identify a change (mutation) in the TYMP gene (also called ECGF1). This gene provides instruction for making the thymidine phoshorylase enzyme. Once a mutation in identified, unaffected family members can undergo genetic testing for that specific mutation.

GeneTests lists the names of laboratories that are performing clinical testing for MNGIE.

Please note: Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.

Last updated on 05-01-20

How might mitochondrial neurogastrointestinal encephalopathy syndrome be diagnosed?

The clinical diagnosis of mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) is based on the presence of severe gastrointestinal dysmotility (when the muscles and nerves of the digestive system do not move food through the digestive tract efficiently), cachexia (wasting away of muscle and fat tissue), ptosis, external ophthalmoplegia (weakness in the muscles that control eye movement), sensorimotor neuropathy, asymptomatic leukoencephalopathy (observed on brain MRI), and a family history consistent with autosomal recessive inheritance.

Direct evidence of MNGIE syndrome can be provided by one of the following:

  • A blood test showing an increase in plasma thymidine concentration (greater than 3 µmol/L) and an increase in plasma deoxyuridine concentration (greater than 5 µmol/L). This is sufficient to make the diagnosis of MNGIE disease.
  • Thymidine phosphorylase enzyme activity in leukocytes (white blood cells) less than 10% of the control mean.

Genetic testing of TYMP, the gene for thymidine phosphorylase (the enzyme deficient in individuals with MNGIE syndrome), detects mutations in approximately all of affected individuals.

Last updated on 05-01-20

How might mitochondrial neurogastrointestinal encephalopathy syndrome be treated?

Establishing the correct diagnosis of MNGIE disease may help avoid unnecessary exploratory abdominal surgeries, risks associated with anesthesia, and inappropriate therapies. Cooperation among multiple specialties including neurology, medical genetics, nutrition, gastroenterology, pain management, psychiatry, and physical/occupational therapy can help with earlier detection and treatment of the various aspects of multi-organ dysfunction that can occur in individuals with MNGIE syndrome. However, once symptoms appear, treatment is generally supportive.

Management of gastrointestinal (GI) dysfunction can include: early attention to swallowing difficulties and airway protection, especially in severely affected individuals; dromperidone for nausea and vomiting; celiac plexus or splanchnic nerve block to reduce abdominal pain; nutritional support such as bolus feedings, gastrostomy tube placement, and total parenteral nutrition; antibiotic therapy for intestinal bacterial overgrowth; and medication regimens that may include morphine, amitriptyline, gabapentin, and phenytoin for relief of neuropathic symptoms. Special schooling arrangements are often necessary. Physical therapy and occupational therapy may help preserve mobility.

It is generally recommended that individuals with MNGIE syndrome avoid drugs that interfere with mitochondrial function including valproate, phenytoin, chloramphenicol, tetracycline, and certain antipsychotic medications.

There are some therapies for MNGIE syndrome under investigation, such as attempting to normalize the concentrations of thymidine inside the cells to reduce the rate of the mitochondrial DNA damage, which progressively increases in an individual over time. Possible future treatments may include decreasing plasma thymidine concentration by reducing renal reabsorption of thymidine, by dialysis, and by enzyme replacement therapy (ERT).

Last updated on 05-01-20

Name: American Gastroenterological Association 4930 Del Ray Avenue
Bethesda, MD, 20814, United States
Phone: 301–654–2055 Fax : 301–654–5920 Email: communication@gastro.org Url: http://www.gastro.org/patient
Name: United Mitochondrial Disease Foundation 8085 Saltsburg Road, Suite 201
Pittsburgh, PA, 15239 , United States
Phone: +1-412-793-8077 Toll Free: 1-888-317-8633 Fax : +1-412-793-6477 Email: info@umdf.org Url: https://www.umdf.org
Name: International Foundation for Functional Gastrointestinal Disorders IFFGD PO Box 170864
Milwaukee, WI, 53217, United States
Phone: +1-414-964-1799 Toll Free: 1-888-964-2001 Fax : +1-414-964-7176 Email: iffgd@iffgd.org Url: https://iffgd.org/
Name: Association of Gastrointestinal Motility Disorders AGMD Bedford, MA, 01730, United States Phone: +1-781-275-1300 Email: info@gimotility-agmd.org Url: https://www.agmdhope.org/
Name: United Leukodystrophy Foundation (ULF) 224 North Second Street Suite 2
DeKalb, IL, 60115 , United States
Phone: 815-748-3211 Toll Free: 800-728-5483 Fax : 815-748-0844 Email: office@ulf.org Url: http://www.ulf.org/
Name: The Mitochondria Research and Medicine Society PO Box 55322
Birmingham, AL,
Phone: 716-907-4349 Fax : 716-845-1047 Email: contact@mitoresearch.org Url: http://www.mitoresearch.org
Name: Gastroparesis and Dysmotilities Association (GPDA) 5520 Dalhart Hill NW Calgary, AB
T3A 1S9
Canada
Phone: 403-247-3215 Email: jkf@gpda.net Url: http://www.digestivedistress.com
Name: MitoAction PO Box 51474
Boston, MA, 02205, United States
Phone: 1-888-MITO-411 (648-6411) for support line Toll Free: 1-888-648-6228 Email: info@mitoaction.org Url: https://www.mitoaction.org/

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