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Hepatic mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme a synthase deficiency
A A Morris1, C V Lascelles, S E Olpin
1Metabolic Unit, Institute of Child Health, London, United Kingdom.
Pediatric Research
|September 4, 1998
Summary
A child with a deficiency in mitochondrial 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase, crucial for ketone body production, experienced hypoglycemia. Management involved avoiding fasting, leading to normal development.
Area of Science:
- Biochemistry
- Metabolic Disorders
- Genetics
Background:
- Hepatocytes contain two main 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase isoenzymes: one in the mitochondrial matrix and one in the cytoplasm.
- The mitochondrial isoenzyme is essential for synthesizing ketone bodies, vital energy sources during fasting periods.
Observation:
- A pediatric patient presented with hypoglycemia at 16 months of age.
- The patient exhibited an impaired ketone body response to fasting and a fatty acid load, but a minor response to a leucine challenge.
- Fibroblast beta-oxidation flux was within normal limits.
Findings:
- No detectable mitochondrial HMG-CoA synthase protein was found in the patient's liver tissue via Western blotting using specific antibodies.
- Total HMG-CoA synthase activity in liver homogenates was only slightly reduced, suggesting the activity originated from non-mitochondrial isoenzymes.
- The study identified a deficiency in the mitochondrial HMG-CoA synthase isoenzyme.
Implications:
- This condition highlights the critical role of mitochondrial HMG-CoA synthase in ketone body synthesis and maintaining metabolic homeostasis.
- Early diagnosis and management, primarily through avoiding prolonged fasting, can prevent severe complications and ensure normal development in affected individuals.
- This case provides valuable insight into the clinical presentation and biochemical consequences of mitochondrial HMG-CoA synthase deficiency.