Carnitine Inborn Errors of Metabolism

Area of Science:

• Biochemistry
• Metabolic Disorders
• Molecular Biology

Background:

• Carnitine is crucial for intermediary metabolism, with dietary intake and endogenous synthesis (~25%) contributing to homeostasis.
• Renal reabsorption also plays a key role in maintaining carnitine levels.
• Lysine and methionine are precursors for carnitine biosynthesis via four key enzymes.

Purpose of the Study:

• To review carnitine metabolism and homeostasis.
• To detail inborn errors of carnitine metabolism, including clinical presentation, diagnosis, and treatment.
• To discuss causes of secondary carnitine deficiency.

Main Methods:

• Review of literature on carnitine metabolism, biosynthesis, transport, and function.
• Analysis of the carnitine-acylcarnitine cycle involving CPT I, CACT, and CPT II.
• Compilation of clinical data on inborn errors of carnitine metabolism.

Main Results:

• Carnitine facilitates long-chain fatty acid transport into mitochondria for beta-oxidation via the carnitine-acylcarnitine cycle.
• Defects in biosynthesis, transport (OCTN2), or the cycle can lead to inborn errors.
• Common clinical manifestations include hypoketotic hypoglycemia, cardiomyopathy, and liver disease.

Conclusions:

• Understanding carnitine metabolism is essential for diagnosing and managing related disorders.
• Inborn errors of carnitine metabolism present variably but share common symptoms.
• Secondary carnitine deficiency warrants consideration in relevant clinical contexts.