Progress in Diagnosing Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like Episodes
1Department of Neurology; Center for Translational Research of Neurology Disease, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning 116011, China.
Objective:
Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a progressive, multisystem affected mitochondrial disease associated with a number of disease-related defective genes. MELAS has unpredictable presentations and clinical course, and it can be commonly misdiagnosed as encephalitis, cerebral infarction, or brain neoplasms. This review aimed to update the diagnosis progress in MELAS, which may provide better understanding of the disease nature and help make the right diagnosis as well.
Data Sources:
The data used in this review came from published peer review articles from October 1984 to October 2014, which were obtained from PubMed. The search term is "MELAS".
Study Selection:
Information selected from those reported studies is mainly based on the progress on clinical features, blood biochemistry, neuroimaging, muscle biopsy, and genetics in diagnosing MELAS.
Results:
MELAS has a wide heterogeneity in genetics and clinical manifestations. The relationship between mutations and phenotypes remains unclear. Advanced serial functional magnetic resonance imaging (MRI) can provide directional information on this disease. Muscle biopsy has meaningful value in diagnosing MELAS, which shows the presence of ragged red fibers and mosaic appearance of cytochrome oxidase negative fibers. Genetic studies have reported that approximately 80% of MELAS cases are caused by the mutation m.3243A>G of the mitochondrial transfer RNA (Leu (UUR)) gene (MT-TL1).
Conclusions:
MELAS involves multiple systems with variable clinical symptoms and recurrent episodes. The prognosis of MELAS patients depends on timely diagnosis. Therefore, overall diagnosis of MELAS should be based on the maternal inheritance family history, clinical manifestation, and findings from serial MRI, muscle biopsy, and genetics.
Insights
Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a complex genetic disorder. Early diagnosis through clinical evaluation, MRI, muscle biopsy, and genetic testing is crucial for better patient outcomes.
Area of Science:
- Neurology
- Genetics
- Mitochondrial Diseases
Background:
- Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a progressive, multisystem mitochondrial disease.
- It presents with unpredictable symptoms and can be misdiagnosed as other neurological conditions.
Purpose of the Study:
- To review diagnostic advancements in MELAS.
- To enhance understanding of MELAS and improve diagnostic accuracy.
Main Methods:
- Systematic review of peer-reviewed articles from PubMed (1984-2014) using the search term "MELAS".
- Analysis focused on clinical features, blood biochemistry, neuroimaging, muscle biopsy, and genetic findings.
Main Results:
- MELAS exhibits genetic and clinical heterogeneity, with genotype-phenotype correlations still unclear.
- Serial functional MRI, muscle biopsy (ragged red fibers, COX-negative fibers), and genetic testing (80% MT-TL1 m.3243A>G mutation) are valuable diagnostic tools.
- Approximately 80% of MELAS cases are linked to the MT-TL1 m.3243A>G mutation.
Conclusions:
- MELAS is a variable, multisystem disorder where timely diagnosis impacts prognosis.
- Comprehensive diagnosis integrates family history, clinical presentation, MRI, muscle biopsy, and genetic analysis.
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