Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare multisystem disorder characterized by progressive degeneration of the muscles of the gastrointestinal tract causing gastrointestinal dysmotility, weakness of extra-ocular muscles causing drooping of the eyelids (ptosis) and restricted eye movements (ophthalmoparesis), degeneration of peripheral nerves causing altered sensation and weakness the distal arms and legs, and general wasting (cachexia). The specific symptoms associated with MNGIE vary from case to case and may include vomiting, nausea, diarrhea, abdominal pain, and numbness or sensations of pins and needles in the hands and feet. . Additional findings may occur in some cases. MNGIE is caused by changes (mutations) in the ECGF1 gene encoding thymidine phosphorylase (TP) and is inherited as an autosomal recessive trait.
MNGIE patients also show changes (e.g. depletions, deletions, or mutations) in the genetic material (DNA) of the mitochondria. Mitochondria, found by the hundreds within virtually every cell of the body, generate most of the cellular energy through the respiratory chain enzymes (complexes I-V), which convert electrons derived from sugars and fats into ATP, the energy currency of the cell. The genetic blueprints for essential components of the respiratory chain are mitochondrial DNA (mtDNA). Disorders due to mitochondrial dysfunction, often defects of the respiratory chain, are called mitochondrial disease. Because energy is essential for many tissue functions, mitochondrial diseases typically affect multiple organs of the body.