Medium Chain Acyl-CoA Dehydrogenase Deficiency

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What is Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)?

• MCADD is also known as ACADM Deficiency.

• Carnitine Deficiency Secondary to MCAD Deficiency.

• Dicarboxylicaciduria due to MCADH Deficiency.

• Dicarboxylicaciduria due to defect in Beta-Oxidation of Fat MCAD Deficiency.

• Non-ketotic Hypoglycaemia and Carnitine Deficiency due to MCAD.

What is MCADD?

• MCADD is a disease in which the body is unable to breakdown fats to make energy. During fasting and periods of intense energy demands, enzymes break down fat to produce energy. Medium-chain acyl-coenzyme A dehydrogenase (MCAD) is one of the enzymes involved in mitochondrial fatty acid Beta-oxidation.

• Different Acyl-CoA Dehydrogenases exist for short (4-6 C), medium (6-10 C), long and very long (12-18 C) chain fatty acids. The ones longer than C12 are oxidized by beta-oxidation down to a 12-carbon fatty acyl-CoA; the ones shorter than C6 can also be oxidized. Medium chain fatty acids cannot be oxidized normally, therefore, it is called MCAD deficiency.

• MCADD is a autosomal recessive trait.

• About 1 in 13000 to 20000 live births have MCADD.

• Occurs mostly in Northern European.

• There are specific signs and symptoms to look for.

• Individuals are normal at birth.

• Usually presents in infancy when an illness (flu, virus, cold, ear infection etc.) causes the child not to eat.

• Vomiting, lethargy, seizures, coma, hypoglycemia, cardiac arrest, breathing complications, and brain damage.

• 25% of affected individuals die in their first crisis.

• More than 50% die from first crisis if occurs after the age of two.

• Long term effects.

• Developmental and behavioral disabilities, speech and language delays, chronic muscle weakness, failure to thrive, cerebral palsy.


• Avoid fasting.

• Eat frequent meals.

• High carbohydrate/low fat diet.

• Avoid intake of medium and long chain fatty acids.


Blood Plasma acylcarnitine analysis:

• Patients with MCADD have more C6 to C10 species in their blood.

Blood Plasma Fatty acid analysis:

• Fatty acids tend to accumulate in the blood of these patients. The fatty acids are: octanoic acid, cis-4 decenoic acid and decanoic acid.

Urine Organic Acid analysis:

• Medium-chain dicarboxylic acids (C6,C8,C10) are higher in urine, while ketones are abnormally low.

Urine acylglycine analysis:

• Patients excrete hexanoylglycine and suberylglycine in urine. These chemicals can be tested using organic acid analysis.

Analysis of fatty acid beta-oxidation in cultured fibroblasts:

• If you incubate a fibroblast culture, you'll see that C6-C10 acylcarnitines accumulate in the medium.

Potential Avenues for Investigation:

Application to the Human Genome Project:

• Advancements will make testing more reliable.

• Has brought about new technology.

• Creation of a Genomics Market.

DNA Chip:

• Minituarization of gene technologies.

• Three types basic types of DNA chips.

• DNA chips diagnostics of the abnormality that causes MCADD.

• Suitable treatments for each individual.

• Eventual target of the technology.


• Fear of DNA testing by general public.

• Detection of MCADD is still based on clinical observation.

• Widespread of technology hindered.

Additional Readings:

Basic Biochemistry

1. Nucleic Acid Structure and Organization
2. DNA Replication and Repair
3. Transcription and RNA Processing
4. Genetic Code, Mutations, and Translation
5. Genetic Regulation
6. Recombinant DNA
7. Amino Acids, Proteins, Enzymes
8. Hormones
9. Vitamins
10. Energy Metabolism
11. Glycolysis and Pyruvate Dehydrogenase
12. Citric Acid Cycle and Oxidative Phosphorylation
13. Glycogen, Gluconeogenesis, and Hexose Monophosphate Shunt
14. Lipid Synthesis and Storage
15. Lipid Mobilization and Catabolism
16. Amino Acid Metabolism Disorders
17. Purine and Pyrimidine Metabolism
18. Electron Transport
19. Citric Acid Cycle and Glyoxylate Cycle
20. Glycolysis
21. Pyruvate Metabolism
22. Mitochondrial ATP formation
23. Gluconeogenesis
24. Glycogen Metabolism
25. Nitrogen Fixation (Metabolism) reactions, and Heme Metabolism
26. Amino Acid Metabolism
27. What is Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)?

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