Carnitine Uptake Defect
Screening
Tested By
Description
Clinical Characteristics
Without treatment, symptoms may vary widely in regard to age of onset, organ involvement, and severity of symptoms depending on the subtype. This would include the metabolic type presenting with metabolic crises and liver disease, myopathic form presenting with cardiomyopathy and skeletal muscle disease, late-onset adulthood type presenting with generalized fatigability, and some who may remain asymptomatic well into adulthood. Patients are at risk of sudden death from arrhythmia at any age.
Initial signs and symptoms of carnitine uptake defect may include:
- Poor appetite
- Vomiting
- Irritability
- Lethargy
- Hypoketotic hypoglycemia
- Sudden death
- Lab findings:
- Anemia
- Metabolic acidosis
- Hypoglycemia
- Muscle weakness
- Cardiomyopathy
- Cardiac arrhythmia
- Hepatomegaly
- Seizures
- Brain injury from hypoglycemia
Incidence
Primary Care Management
Next Steps After a Positive Screen
- Contact the family and evaluate the infant for poor feeding, lethargy, and tachycardia.
- Provide emergency treatment/referral for signs of hypoglycemia, lethargy,
tachycardia, and hepatomegaly. Newborns are rarely symptomatic. See the
ACT Sheet for Decreased CO and Other Acylcarnitines / Carnitine Uptake Defect (ACMG) (
344 KB).
Confirming the Diagnosis
- To confirm the diagnosis of carnitine uptake defect, work with Newborn Screening Services (see NV providers [2]).
- Follow-up testing will include total and free carnitine analysis in plasma and urine. Plasma carnitines may be measured in the mothers of newborns who screen positive to determine if the screen was a false positive due to severe maternal carnitine deficiency (which may be the result of the mother having carnitine uptake disorder or a maternal diet insufficient in natural carnitine). Rapid screening for severity may include glucose, electrolytes, blood gas, ammonia, liver function tests (LFTs), and creatine phosphokinase (CPK). Molecular genetic testing is confirmatory. Carnitine may also be deficient secondary to prematurity, other fatty acid oxidation disorders, or organic acidurias.
If the Diagnosis is Confirmed
- For evaluation and ongoing collaborative management, consult Biochemical Genetics (Metabolics) Clinics (see NV providers [2]).
- Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill (see Carnitine Transporter Deficiency - Information for Parents (STAR-G)).
- A special diet is not required, but general avoidance of fasting is recommended.
- Oral L-carnitine supplements should be continued for life.
- For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.
Resources
Information & Support
After a Diagnosis or Problem is Identified
Families can face a big change when their baby tests positive for a newborn condition. Find information about A New Diagnosis - You Are Not Alone; Caring for Children with Special Health Care Needs; Assistance in Choosing Providers; Partnering with Healthcare Providers, and Top Ten Things to Do After a Diagnosis.
For Professionals
Carnitine Transporter Deficiency - Information for Professionals (STAR-G)
Structured list of information about the condition and links to more information; Screening, Technology, and Research in Genetics.
Primary Carnitine Deficiency (GARD)
Articles, research, case studies, and genetics links; Genetic and Rare Diseases Information Center.
Carnitine Deficiency (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance
in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine
For Parents and Patients
Carnitine Transporter Deficiency - Information for Parents (STAR-G)
A fact sheet, written by a genetic counselor and reviewed by metabolic and genetic specialists, for families who have received
an initial diagnosis of this newborn disorder; Screening, Technology and Research in Genetics.
Primary Carnitine Deficiency (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources;
from the National Library of Medicine.
Fatty Oxidation Disorders (FOD) Family Support Group
Information for families about fatty acid oxidation disorders, support groups, coping, finances, and links to other sites.
Tools
NV ACT Sheet for Carnitine Uptake Defect (ACMG) ( 139 KB)
Provides recommendations for clinical and laboratory follow-up of the newborn with out-of-range screening results, along with
national and local resources for clinicians and families; American College of Medical Genetics.
Confirmatory Algorithms for CO (Free Carnitine) Low / Carnitine Uptake Defect (ACMG) ( 166 KB)
An algorithm of the basic steps involved in determining the final diagnosis of an infant with a positive newborn screen; American
College of Medical Genetics.
Services for Patients & Families in Nevada (NV)
| Service Categories | # of providers* in: | NV | NW | Other states (4) (show) | | MT | NM | RI | UT |
|---|---|---|---|---|---|---|---|---|---|
| Biochemical Genetics (Metabolics) Clinics | 2 | 1 | 2 | 1 | 1 | 3 | |||
| Medical Genetics | 5 | 1 | 8 | 4 | 4 | 6 | |||
| Medical Genetics Clinics | 2 | 1 | 7 | 1 | 1 | 3 | |||
| Newborn Screening Services | 2 | 1 | 4 | 1 | 2 | 3 | |||
For services not listed above, browse our Services categories or search our database.
* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.
Page Bibliography
Amat di San Filippo C, Taylor MR, Mestroni L, Botto LD, Longo N.
Cardiomyopathy and carnitine deficiency.
Mol Genet Metab..
2008;94(2):162-166.
Carnitine is essential for the transfer of long-chain fatty acids across the mitochondrial membrane for subsequent beta-oxidation.
Study results indicate heterozygosity for primary carnitine deficiency is not more frequent in patients with unselected types
of cardiomyopathy and is unlikely to be an important cause of cardiomyopathy in humans.
Magoulas PL, El-Hattab AW, Roy A, Bali DS, Finegold MJ, Craigen WJ.
Diffuse reticuloendothelial system involvement in type IV glycogen storage disease with a novel GBE1 mutation: a case report
and review.
Hum Pathol.
2012.
PubMed abstract
Schimmenti LA, Crombez EA, Schwahn BC, Heese BA, Wood TC, Schroer RJ, Bentler K, Cederbaum S, Sarafoglou K, McCann M, Rinaldo
P, Matern D, di San Filippo CA, Pasquali M, Berry SA, Longo N.
Expanded newborn screening identifies maternal primary carnitine deficiency.
Mol Genet Metab.
2007;90(4):441-5.
PubMed abstract
Primary carnitine deficiency impairs fatty acid oxidation and can result in hypoglycemia, hepatic encephalopathy, cardiomyopathy
and sudden death. Given the lifetime risk of morbidity or sudden death, identification of adult patients with primary carnitine
deficiency is an added benefit of expanded newborn screening programs.
Schulze A, Lindner M, Kohlmuller D, Olgemoller K, Mayatepek E, Hoffmann GF.
Expanded newborn screening for inborn errors of metabolism by electrospray ionization-tandem mass spectrometry: results, outcome,
and implications.
Pediatrics.
2003;111(6 Pt 1):1399-406.
PubMed abstract