Multiple carboxylase deficiency (MCD)
Multiple carboxylase deficiency (MCD)
Alternative name
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Holocarboxylase synthetase (HCS) deficiency
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About the condition
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MCD 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
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2005 |
Incidence in Australia
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Currently unknown
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Enzyme defect
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Deficiency of holocarboxylase synthetase, the enzyme that covalently links biotin to three carboxylases: propionyl-CoA carboxylase, pyruvate carboxylase, and 3-methylcrotonyl-CoA carboxylase.
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Symptoms if untreated
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- Metabolic ketolactic acidosis
- Vomiting, lethargy
- Seizures, hypotonia
- Skin rashes, hair loss
- Hearing loss, optic atrophy
- Recurrent infections
- Intellectual disability
- Coma and death possible
- Later-onset forms occur
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Metabolites on bloodspot screening
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- Increased propionylcarnitine (C3) and hydroxyisovalerylcarnitine (C5OH)
- Increased methylcitrate (second-tier test)
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Diagnostic tests
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- Plasma acylcarnitine profile
- Urine organic acids
- HLCS gene analysis
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Treatment
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Biotin supplementation
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Screening issues
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Biotinidase deficiency is not detected by this screening strategy.
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