Mitochondrial neurogastrointestinal encephalopathy syndrome

Question Question

My daughter has all of the symptoms of MNGIE. She had a muscle biopsy and it came back normal. The geneticist that she saw said further testing is not necessary; is this correct? What can I do to help manage all of her issues?

Answer Answer

The following information may help to address your question:

How might mitochondrial neurogastrointestinal encephalopathy syndrome be diagnosed?
How might mitochondrial neurogastrointestinal encephalopathy syndrome be treated?

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.^[1]

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.^[1]

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.^[1]

Last updated: 6/6/2011

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.^[1]

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.^[1]

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.^[1]

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).^[1]

Last updated: 6/6/2011

We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please contact us.

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GARD Information Specialist

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