3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency
3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency
Alternative name
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3-Methylcrotonylglycinuria
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About the condition
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3-MCC deficiency is an organic acid disorder. It is a hereditary disease that is caused by a missing enzyme needed to convert protein into energy.
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Inheritance
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Autosomal recessive
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Year screening started in WA |
2005 |
Incidence in Australia
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Currently unknown
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Enzyme defect
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- Deficiency of the enzyme 3-methylcrotonyl-CoA carboxylase
- May be seen as part of multiple carboxylase deficiency
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Symptoms if untreated
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- Hypoglycaemia
- Episodic metabolic acidosis
- Significant clinical heterogeneity
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Metabolites on bloodspot screening
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Increased hydroxyisovalerylcarnitine (C5OH).
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Diagnostic tests
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- Plasma acylcarnitine profile
- Urine organic acids
- MCCC1 and MCCC2 gene analysis
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Treatment
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- Low-protein diet
- Carnitine supplementation
- IV glucose and bicarbonate during crisis episodes
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Screening issues
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- Some children may be asymptomatic
- Maternal 3-MCC deficiency may be detected incidentally
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