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Mitochondrial electron transport chain defect presenting as hypoglycemia
M L Freckmann1, D R Thorburn, D M Kirby
1Department of Clinical Genetics, Western Sydney Genetics Program, Australia.
The Journal of Pediatrics
|March 1, 1997
Summary
A profoundly deaf infant with hypoglycemia and lactic acidosis had combined defects in electron transport chain (ETC) complexes I, III, and IV. This highlights the clinical diversity of ETC defects and their potential mimicry of fatty acid oxidation disorders.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Background:
- Electron transport chain (ETC) disorders are a group of heterogeneous genetic conditions affecting cellular energy production.
- Hypoglycemia and lactic acidosis in infants can be caused by various metabolic derangements, including glycogen storage diseases and fatty acid oxidation disorders.
Observation:
- A profoundly deaf female infant presented with hypoglycemia and lactic acidemia following decreased oral intake and vomiting.
- Enzyme studies of the ETC revealed combined defects in complexes I, III, and IV specifically in liver tissue, but not in skeletal muscle.
Findings:
- The patient's presentation of hypoglycemia and lactic acidosis, coupled with specific ETC enzyme deficiencies, underscores the clinical heterogeneity of these disorders.
- The biochemical profile observed in this case mimicked that of a fatty acid oxidation disorder, suggesting potential diagnostic overlap.
Implications:
- Electron transport chain defects should be considered in the differential diagnosis of unexplained hypoglycemia and lactic acidosis in infants, even without a known glycogen storage disorder.
- This case emphasizes the importance of comprehensive metabolic investigations, including ETC enzyme analysis, for accurate diagnosis and management of complex pediatric metabolic conditions.
- Recognizing the potential for ETC defects to present with biochemical features resembling fatty acid oxidation disorders is crucial for timely and appropriate clinical intervention.