[4] When carnitine cannot be transported into tissues, fatty acid oxidation is impaired, leading to a variety of symptoms such as chronic muscle weakness, cardiomyopathy, hypoglycemia and liver dysfunction.

[5] Early cases were reported with liver dysfunction, muscular findings (weakness and underdevelopment), hypoketotic hypoglycemia, cardiomegaly, cardiomyopathy and marked carnitine deficiency in plasma and tissues, combined with increased excretion in urine.

Affected infants show low levels of free carnitine and all other acylcarnitine species by tandem mass spectrometry.

[9] The identification and treatment of these asymptomatic individuals is still developing, as it is not clear whether they require the same levels of intervention as patients identified with SPCD early in life based on clinical presentation.

[6] SPCD is an autosomal recessive condition, meaning a mutated allele must be inherited from each parent for an individual to be affected.

[5] Decreased levels of plasma carnitine inhibit fatty acid oxidation during times of excessive energy demand.

Carnitine is needed to transport long chain fatty acids into the mitochondria, where they can be broken down to produce acetyl-CoA.

Individuals with SPCD cannot produce ketone bodies as energy due to the interruption of fatty acid oxidation.

[6] Although SPCD is an autosomal recessive condition, heterozygotes have been shown to be at an increased risk for developing benign cardiomyopathy compared to wild type individuals.

[5] The first case of SPCD was reported in the 1980s, in a child with fasting hypoketotic hypoglycemia that resolved after treatment with carnitine supplementation.