[2][5] Mutations in this gene result in impaired mitochondrial function, leading to intestinal symptoms as well as neuro-ophthalmologic abnormalities.

[2][5] Additionally, gastrointestinal symptoms such as borborygmi, early satiety, diarrhea, constipation, gastroparesis, nausea, vomiting, weight loss, and diverticulitis may be present in MNGIE patients.

[citation needed] A variety of mutations in the TYMP gene have been discovered that lead to the onset of mitochondrial neurogastrointestinal encephalopathy syndrome.

[2] High nucleoside levels are toxic to mitochondrial DNA and cause mutations that lead to dysfunction of the respiratory chain, and thus, inadequate energy production in the cells.

[2] These symptoms without presentation of disordered eating and warped body image warrant further investigation into the possibility of MNGIE as a diagnosis.

Radiologic studies showing hypoperistalsis, large atonic stomach, dilated duodenum, diverticula, and white matter changes are required to confirm the diagnosis.