Carnitine deficiency is a condition that prevents the body from using various types of fats for energy. There are two types of carnitine deficiency including primary and secondary. Primary carnitine deficiency is a rare condition that particularly occurs during times during fasting. Secondary carnitine deficiency is a more common condition where there is not enough carnitine in the blood. Carnitine is a natural substance that is consumed and then absorbed by cells to process fats and produce energy. It is inherited in an autosomal recessive pattern that means that both copies of the gene must be received in order to have this deficiency. Parents are usually carriers and they give one copy of each mutated gene. Carriers of the SLC22A5 gene mutation may have symptoms of this condition. This gene, when normally functioning, provides instructions for making the OCTN2 protein that transports carnitine to cells. Mutations of the gene can result in an absent or dysfunctional OCTN2 protein which will cause a deficiency of carnitine in the cells. This deficiency as well as the potential buildup of fatty acids in the cell may cause the signs and symptoms of this condition This condition affects approximately 1 in 100,000 newborns globally and 1 in 40,000 newborns in Japan.
Signs and symptoms of this deficiency typically appear before or during early childhood and may include encephalopathy (severe brain dysfunction), cardiomyopathy, confusion, vomiting, muscle weakness, hypoglycemia (low blood sugar) as well as others. Severity varies among individuals and some may be asymptomatic and not experience any signs or symptoms. All individuals with Carnitine Deficiency are at risk for heart failure, liver problems, coma as well as other severe incidences. Problems relating to the deficiency can be triggered during fasting (periods without food) as well as illnesses. It is sometimes mistaken for Reye syndrome which is a severe disorder that has the possibility of occurring in children while recovering from viral infections such as the chicken pox and the flu.
Making a diagnosis includes a review of medical history, symptoms, physical exam, as well as lab tests. This condition can be fatal if untreated however, with oral carnitine supplementation, there is an excellent long-term prognosis.
Treatment varies based on the individual and is often needed lifelong. The main treatment is the lifelong use of L-carnitine which is a natural substance that helps the cells make energy, get rid of waste products, reverse specific heart problems as well as muscle weakness that was caused by the condition. In addition, children also need to eat frequently to prevent a potential problem. It is suggested that children be fed every 4-6 hours and babies even more frequently. Teens and adults may be able to go without eating for up to 12 hours without any complications. Some benefit from a low-fat and high-carb diet. However, any dietary changes should be consulted with a metabolic specialist or a dietician before implementing. Infants and children with the condition should eat extra starchy food and drink more fluids even if they may not be hungry.
Figure 1: Image showing the process by which carnitine usually enters the cell. OCTN2 transports carnitine into the mitochondrial matrix where it can be used to create cellular energy.