Carnitine is crucial for the oxidation of LCFAs. The burden of carnitine deficiency is dysfunction of the liver, heart, and muscle tissues, which are highly dependent on LCFA oxidation. It is believed that the defects in lipid transport to the mitochondria associated with PCD cause a shift toward the glycolytic pathway. This results in accumulation in the mitochondria of acyl-CoAs that esterify free carnitine to form acylcarnitines. These acyl-CoAs, in turn, are easily released from the mitochondria and excreted in the urine.
Lipids accumulate and form small lipid droplets.
Carnitine supplementation has produced variable treatment results. In infants, CPT I deficiency presents as Reye's syndrome, with hepatic encephalopathy, hypoketotic hypoglycemia, and hyperammonemia. In adults, carnitine deficiency syndrome most often results from CPT II deficiency. The gene for CPT II is located on chromosome 11p11-p13, and missense mutations have been described. CPT II deficiency represents the most common cause of myoglobinuria in young adults.