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Multiple mtDNA deletions with features of MNGIE
J Vissing1, K Ravn, E R Danielsen
1Department of Neurology and the Copenhagen Muscle Research Center, National University Hospital, Rigshospitalet, Copenhagen, Denmark. vissing@rh.dk
Neurology
|September 26, 2002
Summary
Two sisters experienced gastrointestinal issues and neurological problems due to a likely nuclear DNA mutation affecting mitochondrial function. This condition mimics MNGIE but without brain abnormalities, suggesting a novel genetic cause.
Area of Science:
- Genetics
- Neurology
- Mitochondrial Biology
Background:
- Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare genetic disorder.
- It typically presents with gastrointestinal dysmotility, cachexia, ptosis, ophthalmoplegia, and progressive external ophthalmoplegia.
Observation:
- Two sisters presented with gastrointestinal malabsorption, pain, and polyneuropathy.
- Clinical signs included ophthalmoplegia, neurogenic electromyography (EMG), and COX-negative muscle fibers.
Findings:
- One patient exhibited reduced mitochondrial complex I-IV activity, multiple mitochondrial DNA (mtDNA) deletions, and depletion.
- Crucially, no mutations in thymidine phosphorylase (TP) or dNT-2 genes were found, and TP activity was normal.
- Brain MRI scans were also normal, differentiating this from classic MNGIE.
Implications:
- The findings suggest a potential nuclear DNA mutation disrupting intergenomic signaling in mitochondria.
- This case expands the phenotypic spectrum of mitochondrial disorders.
- It highlights the importance of investigating nuclear gene defects in suspected mitochondrial diseases.