|
Alternative names
|
- Methylmalonyl-CoA mutase deficiency
- Cbl A, Cbl B, Cbl C, Cbl D
|
|
About the condition
|
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.
|
|
Inheritance
|
Autosomal recessive
|
Year screening started in WA
|
2005 |
|
Incidence in Australia
|
Approximately 1 in 75,000 births
|
|
Enzyme defect
|
- Defect in methymalonyl-CoA mutase or synthesis of its adenosylcobalamin cofactor
- At least five distinct biochemical causes of this disorder have been identified
|
|
Symptoms if untreated
|
- Episodic ketoacidosis
- Hyperammonaemia
- Vomiting, FTT
- Seizures, intellectual disability
- Coma and death possible
- Later-onset and milder forms occur
|
|
Metabolites on bloodspot screening
|
- Increased propionylcarnitine (C3)
- Increased methylmalonate (second-tier test)
|
|
Diagnostic tests
|
- Plasma acylcarnitine profile
- Urine organic acids
- Plasma MMA and total homocysteine
- Vitamin B12
- MMA gene panel
|
|
Treatment
|
- Low-protein diet
- Vitamin B12 for responsive forms
- Carnitine supplementation
- More intensive treatment during acute crises
|
|
Screening issues
|
- Screening will detect mutase deficiency, Cbl A, B, C and D forms.
- Later-onset and milder variants may not be detected
|