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Fatal combined defects in mitochondrial multienzyme complexes in two siblings
B H Robinson1, W Chow, R Petrova-Benedict
1Research Institute, Hospital For Sick Children, Toronto, Ontario, Canada.
European Journal of Pediatrics
|May 1, 1992
Summary
This study investigates mitochondrial respiratory chain defects in infants with unexplained neurological disorders. Multiple enzyme complex failures were identified in muscle and skin cells, suggesting a severe genetic condition affecting energy production.
Area of Science:
- Biochemistry
- Genetics
- Pediatric Neurology
Background:
- Mitochondrial respiratory chain disorders are a group of inherited metabolic diseases.
- These disorders can lead to severe neurological impairment and early death in infants.
Observation:
- A female infant with intrauterine growth retardation presented with hypotonia, weakness, and respiratory distress, dying at 6 days.
- A previous sibling exhibited similar symptoms, including seizures and dysmyelination, and died at 3 months.
- Post-mortem examination revealed basal ganglia damage in both siblings.
Findings:
- Cultured skin fibroblasts showed defects in pyruvate dehydrogenase complex, cytochrome c oxidase, and succinate cytochrome c reductase activities.
- Muscle mitochondria displayed similar defects and failed to assemble cytochrome c oxidase and complex I.
- Liver mitochondria were unaffected, indicating tissue-specific mitochondrial dysfunction.
Implications:
- This case highlights the potential for multiple mitochondrial respiratory chain complex defects in severe pediatric neurological disorders.
- The findings suggest a genetic basis for the observed enzyme deficiencies and assembly defects.
- This research underscores the importance of investigating mitochondrial function in unexplained infant deaths and neurological conditions.