This is a rare mitochondrial condition which is due not to a defect in mitochondrial DNA but due to a defect in an enzyme called thymidine phosphorylase. As this is not inherited through the mitochondrial DNA, the disease only occurs if both parents carry a faulty gene, giving the patient two faulty copies of the thymidine phosphorylase gene. This is called an autosomal recessive pattern of inheritance
MNGIE presents predominantly either with disturbances of bowel function or with weakness that is largely due to a damaged nerve supply. It is quite variable in the severity of the illness with some patients developing quite severe disease early in life, whereas others may develop symptoms much later in life. The disturbance of bowel function can be severe, as can the muscle weakness. These are usually the main symptomatic issues. Other complications can develop, and approximately 10% of patients may develop cognitive problems.
The diagnosis of MNGIE is made by measuring thymidine levels in the blood and urine. This is often then confirmed by direct measurements of the enzyme thymidine phosphorylase and genetic confirmation. At present the condition remains very difficult to treat, but discussion with specialists in mitochondrial disease is very important so that treatment can be considered at an early stage. Research is continuing in this area.
It is likely that if you do have this condition, your doctor would be in touch with specialists about any new therapy and it may be that you will be asked to take part in any clinical trials if you felt this would be helpful for your condition.