[Elevated C8 with Lesser Elevations of C6 and C10 Acylcarnitine]
Medium-chain Acyl-CoA Dehydrogenase Deficiency (MCAD)
Differential Diagnosis: Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency.
Condition Description: MCAD deficiency is a fatty acid oxidation (FAO) disorder. FAO occurs during prolonged fasting and/or periods of increased energy demands (fever, stress) when energy production relies increasingly on fat metabolism. In an FAO disorder, fatty acids and potentially toxic derivatives accumulate because of a deficiency in one of the mitochondrial FAO enzymes.
MEDICAL EMERGENCY - TAKE THE FOLLOWING IMMEDIATE ACTIONS:
- Contact family to inform them of the newborn screening result and ascertain clinical status (poor feeding, vomiting, lethargy)
- Consult with pediatric metabolic specialist
- Evaluate the newborn (hepatomegaly, poor feeding, lethargy, hypotonia). If signs are present or if infant is ill, initiate emergency treatment with IV glucose. Transport to hospital for further treatment in consultation with metabolic specialist. If infant is normal initiate timely confirmatory/diagnostic testing, as recommended by specialist
- Educate family about need for infant to avoid fasting. Even if mildly ill, immediate treatment with IV glucose is needed
- Report findings to state newborn screening program (Carleigh Soule at 307-777-6297)
Diagnostic Evaluation: Plasma acylcarnitine analysis will show elevated octanoylcarnitine (C8). Urine acylglycine will show elevated hexanoylglycine. Diagnosis is confirmed by mutation analysis of the MCAD gene.
Clinical Considerations: MCAD deficiency is usually asymptomatic in the newborn although it can present acutely in the neonate with hypoglycemia, metabolic acidosis, hyperammonemia, and hepatomegaly. MCAD deficiency is associated with high mortality unless treated promptly; milder variants exist. Hallmark features include vomiting, lethargy, and hypoketotic hypoglycemia. It is a significant cause of death.
Additional Information: (Click on the name to take you to the website)
Genetic Home Reference Wyoming Department of Health
Gene Tests Colorado Newborn Screening
American Academy of Pediatrics http://pediatrics.aappublications.org/
For Algorithm: http://www.acmg.net/resources/policies/ACT/Visio-C8_vsd;_C6-C10_(4-29-06).pdf