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Mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes: a distinctive clinical syndrome
Abstract:
We report on two patients who have a mitochondrial myopathy, encephalopathy, lactic acidosis, and recurrent cerebral insults that resemble strokes (MELAS). These two and nine other reported patients share the following features: ragged red fibers evident on muscle biopsy, normal early development, short stature, seizures, and hemiparesis, hemianopia, or cortical blindness. Lactic acidemia is a common finding. We believe that MELAS represents a distinctive syndrome and that it can be differentiated from two other clinical disorders that also are associated with mitochondrial myopathy and cerebral disease: Kearns-Sayre syndrome and the myoclonus epilepsy ragged red fiber syndrome. Existing information suggests that MELAS is transmitted by maternal inheritance. The ragged red fibers suggest an abnormality of the electron transport system, but the precise biochemical disorders in these three clinical syndromes remain to be elucidated.
Insights
Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke (MELAS) is a distinct syndrome characterized by specific neurological and muscle abnormalities. Further research is needed to elucidate the precise biochemical defects in MELAS and related mitochondrial disorders.
Area of Science:
- Neurology
- Genetics
- Mitochondrial Diseases
Background:
- Mitochondrial myopathies are a group of inherited disorders affecting energy production.
- Distinct clinical syndromes associated with mitochondrial myopathy and central nervous system involvement exist.
Observation:
- Two patients presented with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).
- Shared features include ragged red fibers on muscle biopsy, normal early development, short stature, seizures, and focal neurological deficits.
- Lactic acidemia is a frequent biochemical finding.
Findings:
- MELAS is proposed as a distinct syndrome, differentiated from Kearns-Sayre syndrome and myoclonus epilepsy ragged red fiber syndrome.
- Maternal inheritance is suggested for MELAS.
- Ragged red fibers indicate a potential electron transport system abnormality, but specific biochemical defects require further investigation.
Implications:
- Accurate differentiation of MELAS is crucial for diagnosis and management.
- Understanding the genetic and biochemical basis of MELAS can inform therapeutic strategies.
- Further research into mitochondrial electron transport chain disorders is warranted.