Carnitine transporter defect (CTD)
Carnitine transporter defect (CTD)
Alternative names
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- Systemic or primary carnitine deficiency
- Carnitine uptake defect
- Deficiency of plasma-membrane carnitine transporter
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About the condition
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CTD is a fatty acid oxidation disorder. It is a hereditary disease that is caused by a missing protein needed to reabsorb carnitine in the kidney. The features of the condition are caused by intracellular carnitine deficiency, which is needed to convert fat 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 WA
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Approximately 1 in 40,000 births
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Defect
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Caused by defects in the SLC22A5 gene, which encodes the carnitine transporter OCTN2.
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Symptoms if untreated
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- Hypoketotic hypoglycaemia
- Vomiting, lethargy, seizures and coma
- Hepatomegaly
- Cardiomyopathy
- Skeletal myopathy
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Metabolites on bloodspot screening
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- Decreased free carnitine (C0)
- Decreased long-chain acylcarnitines (C16 and C18)
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Diagnostic tests
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- Plasma carnitine
- Plasma acylcarnitine profile
- Urine carnitine fractional excretion
- SLC22A5 gene analysis
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Treatment
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- Carnitine supplementation
- Avoidance of fasting
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Screening issues
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- Some children with CTD may be asymptomatic
- Maternal CTD deficiency may be detected incidentally
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