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Medium chain acyl-CoA dehydrogenase deficiency
1INSERM U75, Centre Hospitalo-Universitaire Necker, Paris, France.
Abstract:
From 65 reported cases of medium chain acyl-CoA dehydrogenase deficiency, we found an average presenting age of 13.5 months and a mean age at death of 18.5 months. One quarter of patients died of a Reye-like syndrome and/or sudden infant death. In half the cases there had been at least one sibling death. Asymptomatic cases were not uncommon (12% of cases). The crises were generally induced by a prolonged fast and after a viral prodromal phase in three quarters of cases. The crises consisted of somnolence progressing to lethargy which could lead to coma. Vomiting was frequent (60% of cases). Seizures, which were found in 29% of cases, represented a bad prognosis. The physical examinations revealed frequently a variable and regressive anicteric hepatomegaly. Blood and urine analysis revealed in most instances hypoglycaemia (96% of cases) with hypoketonuria and sometimes metabolic acidosis. Hepatic and muscular cytolytic enzymes were frequently raised, as were plasma ammonia, urea, and uric acid. Plasma total or free carnitine concentrations, especially non-fasting, were diminished in most cases. Plasma saturated medium chain fatty acids and particularly unsaturated cis-4-decenoate were on the other hand raised during the crises or during fasting. Urinary organic acid analysis revealed a characteristic profile of medium chain aciduria: C6-C10 dicarboxylic acids, hydroxy acids, glycine conjugates, and carnitine conjugates. Oral loading tests with carnitine or phenylpropionate allow a precise diagnosis. The diagnosis is confirmed by specific assays in various tissues. Avoidance of prolonged fasting seems to be the mainstay of treatment.
Insights
Medium chain acyl-CoA dehydrogenase deficiency (MCAD) often presents in infancy, with crises triggered by fasting and viral illness. Early diagnosis and avoiding prolonged fasting are crucial for managing this condition.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Background:
- Medium chain acyl-CoA dehydrogenase deficiency (MCAD) is an inherited metabolic disorder.
- It affects the body's ability to break down fats for energy.
Purpose of the Study:
- To analyze clinical features, diagnostic methods, and outcomes of MCAD.
- To highlight the importance of early diagnosis and management.
Main Methods:
- Retrospective analysis of 65 reported cases of MCAD.
- Review of clinical presentations, laboratory findings, and diagnostic tests.
- Evaluation of treatment outcomes, focusing on dietary management.
Main Results:
- Average presentation at 13.5 months, with a mean age at death of 18.5 months.
- Crises often precipitated by fasting and viral infections, presenting with lethargy, coma, and vomiting.
- Hypoglycemia, metabolic acidosis, elevated ammonia, and specific urinary organic acid profiles were common.
- Carnitine deficiency and elevated medium-chain fatty acids were observed.
- Diagnosis confirmed by oral loading tests and tissue assays.
Conclusions:
- MCAD presents with characteristic metabolic derangements and can be fatal if untreated.
- Early identification through biochemical markers and genetic testing is vital.
- Avoiding prolonged fasting is the primary therapeutic strategy.