What is the consequence of carnitine deficiency?

Carnitine plays a crucial role in the transport of long-chain fatty acids into the mitochondria for beta-oxidation, which is the process of breaking down fatty acids to produce energy. A deficiency in carnitine impairs this transport mechanism, resulting in the inability to effectively metabolize long-chain fatty acids. This leads to an accumulation of these unoxidized fatty acids in the cytoplasm and decreased energy production, particularly during periods of fasting or increased energy demand.

When carnitine is deficient, the body cannot utilize long-chain fatty acids as an energy source, which can result in hypoketotic hypoglycemia and muscle weakness since glucose becomes the primary fuel source. The body's reliance on glycolysis and glucose metabolism is inadequate for energy needs, especially during fasting or prolonged exercise.

Unlike long-chain fatty acids, short-chain and medium-chain fatty acids can diffuse into mitochondria more easily and do not require carnitine for transport. Therefore, while those types of fatty acids can still be metabolized, long-chain fatty acids are the specific substrates that cannot be used effectively in the context of carnitine deficiency.