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Mitochondrial myopathies with necrotizing encephalopathy of the Leigh type
J Peiffer1, B Kustermann-Kuhn, W Mortier
1Institute of Brain Research, University of Tübingen, FRG.
Abstract:
Two patients with mitochondrial encephalomyopathy (MEP) serve to emphasize the variability of this group of diseases. Cerebral insults, mitochondrial cardiopathy, relapsing ileus, cerebral angioma, ataxia, and myoclonic seizures characterized the first case of an adult man with similar diseases in his family, interpreted as transitional form between mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and myoclonus epilepsy associated with ragged red fibers (MERRF). The second patient, a floppy infant with cardiomyopathy and myoclonism, statomotoric and mental retardation showed combined defects in mitochondrial respiratory chain at NADH-CoQ reductase and cytochrome c oxidase and a deficiency of carnitine. In both patients neuropathologically criteria of Leigh's syndrome could be demonstrated in the cerebral cortex, in case 2 also clinically. The classificatory problems of the relationships between KSS, MELAS, MERRF, Leigh's as well as Alpers' syndromes are discussed.
Insights
Mitochondrial encephalomyopathy (MEP) presents diverse symptoms, challenging classification. These cases highlight overlapping features between MELAS, MERRF, and Leigh syndrome, emphasizing disease variability.
Area of Science:
- Neurology
- Genetics
- Biochemistry
Background:
- Mitochondrial encephalomyopathies (MEP) encompass a spectrum of genetic disorders.
- Variability in clinical presentation and genetic defects complicates diagnosis and classification.
Observation:
- Case 1: Adult male with cerebral insults, mitochondrial cardiopathy, ileus, angioma, ataxia, and myoclonic seizures, exhibiting features transitional between MELAS and MERRF.
- Case 2: Infant with cardiomyopathy, myoclonism, developmental delay, and combined mitochondrial respiratory chain defects (NADH-CoQ reductase and cytochrome c oxidase), alongside carnitine deficiency.
Findings:
- Both patients demonstrated neuropathological criteria for Leigh's syndrome.
- The first patient's presentation suggested a hybrid form of mitochondrial disorders.
- The second patient exhibited complex mitochondrial dysfunction and carnitine deficiency.
Implications:
- These cases underscore the significant overlap and variability within mitochondrial encephalomyopathies.
- The findings necessitate a re-evaluation of classification systems for KSS, MELAS, MERRF, Leigh's, and Alpers' syndromes.
- Understanding these overlaps is crucial for accurate diagnosis and therapeutic strategies in mitochondrial diseases.