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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.

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 may find information on treatment or management of primary carnitine deficiency or some of its symptoms in the links below, particularly the links for 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.

  • MedlinePlus - Health information
    • Health Topic: Metabolic Disorders (http://www.nlm.nih.gov/medlineplus/metabolicdisorders.html)
    • Health Topic: Newborn Screening (http://www.nlm.nih.gov/medlineplus/newbornscreening.html)
  • Additional NIH Resources - National Institutes of Health
    NIH Office of Dietary Supplements (http://ods.od.nih.gov/factsheets/carnitine.asp)
  • Educational resources - Information pages
    • Iowa Department of Public Health (http://idph.state.ia.us/genetics/common/pdf/ctd.pdf)
    • Oregon Department of Human Services Newborn Screening: Carnitine transporter defect (http://oregon.gov/DHS/ph/nbs/docs/carnitinetransport.pdf)
    • Orphanet (http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=158)
    • Screening, Technology, and Research in Genetics (http://www.newbornscreening.info/Parents/fattyaciddisorders/Carnitine.html)
    • The Linus Pauling Institute (http://lpi.oregonstate.edu/infocenter/othernuts/carnitine/)
    • Virginia Department of Health (http://www.vahealth.org/genetics/documents/ParentfactsPDF/Carnitine%20Uptake%20Deficiency%20-%20Parent%20Fact%20Sheet.pdf)
  • Patient support - For patients and families
    • Children Living with Inherited Metabolic Diseases (CLIMB) (http://climb.org.uk/)
    • Fatty Oxidation Disorders Support (http://www.fodsupport.org/index.htm)
    • National Organization for Rare Disorders (http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Carnitine%20Deficiency%20Syndrome)
    • United Mitochondrial Disease Foundation (http://www.umdf.org/)

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

  • Gene Tests - DNA tests ordered by healthcare professionals (http://www.genetests.org/query?testid=3164)
  • ACTion Sheets - Newborn screening follow up
    • Decreased C0 and other acylcarnitines (http://www.acmg.net/resources/policies/ACT/ACT_sheet_C0_5-3-06_ljo.pdf)
  • ClinicalTrials.gov - Linking patients to medical research (http://clinicaltrials.gov/search/condition=%22lipid+metabolism%2C+inborn+errors%22+OR+%22primary+carnitine+deficiency%22)
  • PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=PubMed&term=((carnitine+uptake+defect[TIAB])+OR+(carnitine+transporter+deficiency[TIAB])+OR+(primary+carnitine+deficiency[TIAB])+OR+(renal+carnitine+transport+defect[TIAB])+OR+(systemic+carnitine+deficiency[TIAB]))+AND+english[la]+AND+human[mh]&orig_db=PubMed&filters=ON&pmfilter_EDatLimit=1080+Days)
  • Online Books - Medical and science texts
    Scriver's Online Metabolic and Molecular Bases of Inherited Disease (OMMBID): Mitochondrial Fatty Acid Oxidation Disorders (http://books.mcgraw-hill.com/getommbid.php?isbn=0071459960&template=ommbid&c=101)
  • OMIM - Genetic disorder catalog (http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=212140)

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

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

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

  • See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.
  • Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).
  • Submit your question to Ask the Geneticist (http://www.askthegen.org/).

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 (http://ghr.nlm.nih.gov/glossary).

References
  • Amat di San Filippo C, Pasquali M, Longo N. Pharmacological rescue of carnitine transport in primary carnitine deficiency. Hum Mutat. 2006 Jun;27(6):513-23. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=16652335)
  • Angelini C, Vergani L, Martinuzzi A. Clinical and biochemical aspects of carnitine deficiency and insufficiency: transport defects and inborn errors of beta-oxidation. Crit Rev Clin Lab Sci. 1992;29(3-4):217-42. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=1489518)
  • Bartlett K, Eaton S. Mitochondrial beta-oxidation. Eur J Biochem. 2004 Feb;271(3):462-9. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=14728673)
  • Dobrowolski SF, McKinney JT, Amat di San Filippo C, Giak Sim K, Wilcken B, Longo N. Validation of dye-binding/high-resolution thermal denaturation for the identification of mutations in the SLC22A5 gene. Hum Mutat. 2005 Mar;25(3):306-13. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=15714519)
  • Hoppel C. The role of carnitine in normal and altered fatty acid metabolism. Am J Kidney Dis. 2003 Apr;41(4 Suppl 4):S4-12. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=12751049)
  • Lahjouji K, Mitchell GA, Qureshi IA. Carnitine transport by organic cation transporters and systemic carnitine deficiency. Mol Genet Metab. 2001 Aug;73(4):287-97. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=11509010)
  • Lamhonwah AM, Olpin SE, Pollitt RJ, Vianey-Saban C, Divry P, Guffon N, Besley GT, Onizuka R, De Meirleir LJ, Cvitanovic-Sojat L, Baric I, Dionisi-Vici C, Fumic K, Maradin M, Tein I. Novel OCTN2 mutations: no genotype-phenotype correlations: early carnitine therapy prevents cardiomyopathy. Am J Med Genet. 2002 Aug 15;111(3):271-84. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=12210323)
  • Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet. 2006 May 15;142(2):77-85. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=16602102)
  • Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet. 2006 May 15;142(2):77-85. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=16602102)
  • Ramsay RR, Gandour RD, van der Leij FR. Molecular enzymology of carnitine transfer and transport. Biochim Biophys Acta. 2001 Mar 9;1546(1):21-43. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=11257506)
  • Stanley CA. Carnitine deficiency disorders in children. Ann N Y Acad Sci. 2004 Nov;1033:42-51. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=15591002)
  • Tein I. Carnitine transport: pathophysiology and metabolism of known molecular defects. J Inherit Metab Dis. 2003;26(2-3):147-69. Review. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=12889657)
  • Wang Y, Korman SH, Ye J, Gargus JJ, Gutman A, Taroni F, Garavaglia B, Longo N. Phenotype and genotype variation in primary carnitine deficiency. Genet Med. 2001 Nov-Dec;3(6):387-92. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&dopt=Abstract&list_uids=11715001)

 

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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

 
Reviewed: July 2006
Published: May 4, 2009