Alternative names
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- Methylmalonyl-CoA mutase deficiency
- Cbl A, Cbl B, Cbl C, Cbl D
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About the condition
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MMA is an organic acid disorder. It is a hereditary disease that is caused by a missing enzyme needed to convert protein into energy. The disorder can also result from deficiency of the cobalamin cofactor required by the mutase enzyme.
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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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Approximately 1 in 75,000 births
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Enzyme defect
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- Defect in methymalonyl-CoA mutase or synthesis of its adenosylcobalamin cofactor
- At least five distinct biochemical causes of this disorder have been identified
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Symptoms if untreated
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- Episodic ketoacidosis
- Hyperammonaemia
- Vomiting, FTT
- Seizures, intellectual disability
- Coma and death possible
- Later-onset and milder forms occur
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Metabolites on bloodspot screening
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- Increased propionylcarnitine (C3)
- Increased methylmalonate (second-tier test)
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Diagnostic tests
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- Plasma acylcarnitine profile
- Urine organic acids
- Plasma MMA and total homocysteine
- Vitamin B12
- MMA gene panel
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Treatment
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- Low-protein diet
- Vitamin B12 for responsive forms
- Carnitine supplementation
- More intensive treatment during acute crises
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Screening issues
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- Screening will detect mutase deficiency, Cbl A, B, C and D forms.
- Later-onset and milder variants may not be detected
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