Skip Navigation
About   Site Map   Contact Us
A service of the U.S. National Library of Medicine®
Printer-friendly version
Primary carnitine deficiency
 Quick links to this topic
 Health information
 National Institutes of Health
 Information pages
 For patients and families
 DNA test labs
 Newborn screening
 Research studies
 Recent literature
 Medical and science texts
 Genetic disorder catalog

Primary carnitine deficiency

Reviewed July 2006

What is primary carnitine deficiency?

Primary carnitine deficiency is a condition that prevents the body from using fats for energy, particularly during periods without food (fasting). Carnitine, a natural substance acquired mostly through diet, is used by cells to process fats and produce energy. In people with primary carnitine deficiency, proteins called carnitine transporters do not work properly. These proteins normally bring carnitine into cells and prevent the escape of carnitine from the body in urine.

Typically, initial signs and symptoms of this disorder occur during infancy or early childhood and often include changes in brain tissue (encephalopathy) resulting in functional abnormalities; an enlarged, poorly pumping heart (cardiomyopathy); confusion; vomiting; muscle weakness; and low blood sugar (hypoglycemia). Serious complications such as heart failure, liver problems, coma, and sudden unexpected death are also a risk. Severe illness due to primary carnitine deficiency can be triggered by periods of fasting or illnesses such as viral infections, particularly when eating is reduced.

This condition is sometimes mistaken for Reye syndrome, a severe disorder that develops in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.

How common is primary carnitine deficiency?

The incidence of primary carnitine deficiency in the general population is approximately 1 in 100,000 newborns. In Japan, this disorder affects 1 in every 40,000 newborns.

What genes are related to primary carnitine deficiency?

Mutations in the SLC22A5 gene cause primary carnitine deficiency.

Mutations in the SLC22A5 gene lead to the production of defective carnitine transporters. As a result of reduced transport of carnitine into cells, cells are not supplied with an adequate amount of this substance and it is lost from the body in urine. Without carnitine, fats cannot be processed correctly and are not converted into energy, which can lead to characteristic signs and symptoms of this disorder.

Read more about the SLC22A5 gene.

How do people inherit primary carnitine deficiency?

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the mutated gene. Carriers of SLC22A5 mutations may have some signs and symptoms related to the condition.

Where can I find information about treatment for primary carnitine deficiency?

You might find information on treatment of primary carnitine deficiency in Educational resources and Patient support.

Where can I find additional information about primary carnitine deficiency?

You may find the following resources about primary carnitine deficiency helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for primary carnitine deficiency?

  • Carnitine transporter deficiency
  • carnitine uptake defect
  • carnitine uptake deficiency
  • CUD
  • Renal carnitine transport defect
  • Systemic carnitine deficiency

What if I still have specific questions about primary carnitine deficiency?

Where can I find general information about genetic conditions?

What glossary definitions help with understanding primary carnitine deficiency?

acids ; autosomal ; autosomal recessive ; cardiomyopathy ; carnitine ; carrier ; cell ; coma ; complication ; deficiency ; encephalopathy ; fasting ; fatty acids ; gene ; heart failure ; hypoglycemia ; incidence ; infection ; mutation ; newborn screening ; oxidation ; population ; protein ; recessive ; renal ; screening ; sign ; symptom ; syndrome ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (13 links)


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

Reviewed: July 2006
Published: May 4, 2009