A multisystem disorder caused by a defective thymidine phosphorylase, and characterized by the main symptoms such as peripheral neuropathy, digestive problems, chronic progressive external ophthalmoplegia, and leukoencephalopathy
MNGIE syndrome is a type of mitochondrial myopathy. A mitochondrial myopathy is a type of myopathy associated with mitochondrial dysfunction. One of the major distinctions of this condition is the inability of the muscle to perform properly. In MNGIE syndrome, the underlying cause is the defective thymidine phosphorylase. This enzyme becomes defective as a result of the expression of a faulty TYMP gene. This gene, however, is not a mitochondrial DNA but a nuclear DNA. Thus, MNGIE syndrome is inherited not in a mitochondrial pattern but in an autosomal recessive pattern. This means that the individual would inherit the disorder when both faulty genes (one from the father and the other from the mother) are inherited. The onset of the disease is typically before the person reaches the age of 20.
MNGIE syndrome is characterized by the following symptoms: ptosis, limb weakness, digestive problems (e.g. chronic diarrhea), PEO, chronic progressive external ophthalmoplegia, and leukoencephalopathy. These symptoms are a result of the excessive thymidine nucleoside levels due to a lack of thymidine phosphorylase activity. Too much thymidine nucleoside is toxic to the mitochondrial DNA, which eventually leads to the dysfunction of the mitochondria.
MNGIE without leukoencephalopathy is a variant of MNGIE syndrome and the faulty gene involved is the POLG gene.
- Mitochondrial neurogastrointestinal encephalopathy syndrome