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Carnitine Palmitoyltransferase 1A (CPT 1) Deficiency

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Guidance for primary care clinicians receiving a positive newborn screen result

Other Names

Carnitine palmitoyltransferase deficiency, type 1A (CPT 1)
Carnitine palmitoyltransferase 1 deficiency
CPT1A
CPT 1 liver

ICD-10 Coding

E71.314, Muscle carnitine palmitoyltransferase deficiency

Disorder Category

Fatty acid oxidation disorder

Screening

Abnormal Finding

Elevated C0 and C0/(C16+C18) ration

Tested By

Tandem mass spectrometry (MS/MS); sensitivity=100%; specificity=N/A% [Schulze: 2003]

Description

Carnitine palmitoyltransferase 1A (CPT 1) is a mitochondrial enzyme involved in the conjugation of fatty acids to carnitine for subsequent transfer inside mitochondria through the action of a translocase. Mutations in the CPT 1A gene cause CPT1. Deficiency of CPT 1 results in impaired energy production, usually manifest during periods of prolonged fasting and/or increased energy demands (fever, stress), resulting in rapid onset of hypoglycemic crises. CPT 1A is predominantly expressed in the liver, and the muscle and the heart are not primarily affected in this condition.

Clinical Characteristics

With treatment of CPT 1, episodes of hypoglycemia, and consequent neurologic injury, may be avoided.
Without treatment, injury from hypoglycemic episodes may lead to developmental delay, seizures, coma, and death. Acute fatty liver of pregnancy may occur in a heterozygous mother of a homozygous fetus.
Initial signs/symptoms of CPT1 deficiency typically begin suddenly in association with an illness between 8-18 months of life and may be life-threatening. They usually include:
  • Poor appetite
  • Vomiting
  • Lethargy
  • Lab findings:
    • Hyperammonemia
    • Elevated transaminases
    • Metabolic acidosis
    • Hypoglycemia

Incidence

CPT 1 is rare, with fewer than 40 known cases. [Schulze: 2003]

Inheritance

Autosomal recessive

Primary Care Management

Next Steps After a Positive Screen

  • Contact the family and evaluate the infant for lethargy, poor feeding, or hepatomegaly.
  • Provide emergency treatment/referral for symptoms of hypoglycemia, lethargy, or seizures.

Confirming the Diagnosis

  • To confirm the diagnosis of CPT 1, work with Newborn Screening Services (see UT providers [3]).
  • Additional testing may include quantitative plasma acylcarnitine profile, enzyme activity assay in cultured fibroblasts, CPT 1A gene sequencing. The increased C0/(C16+C18) ratio is better detected from the dried blood spot collected for newborn screening. In plasma, C0 can be only mildly increased with low levels of C16 and C18.

If the Diagnosis is Confirmed

  • For evaluation and ongoing collaborative management, consult Biochemical Genetics (Metabolics) Clinics (see UT providers [3]).
  • Educate the family regarding signs, symptoms, and the need to avoid fasting and seek urgent care when the infant becomes ill. See CPT1 Deficiency - Information for Parents (STAR-G) for additional information.
  • Provide a letter and, when old enough, a MedicAlert bracelet indicating the risk for hypoglycemia and need for urgent treatment with IV glucose when illness or stress lead to symptoms.
  • Frequent, low fat, and high carbohydrate meals and snacks and, for infants, cornstarch feedings at night as a slow-release carbohydrate source.
  • Medium-chain triglyceride oil supplements may be indicated for some children.
For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions. Refer to Early Intervention for Children with Disabilities/Delays (see UT providers [55]) as needed.

Resources

Information & Support

Related Portal Content
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; Top Ten Things to Do After a Diagnosis.

For Professionals

CPT1 Deficiency (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular pathogenesis; from the University of Washington and the National Library of Medicine.

For Parents and Patients

CPT1 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.

CPT1 Deficiency (Genetics Home Reference)
Excellent, detailed review of condition for patients and families; sponsored by the U.S. National Library of Medicine.

United Mitochondrial Disease Foundation
The United Mitochondrial Disease Foundation site provides parents and providers with information over 40 mitochondrial diseases; definitions of medical terms; professional articles; chapter links; newsletters; event information; and links to other sites.

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

Algorithm for Carnitine Palmitoyltransferase 1A (CPT 1) Deficiency [Elevated C0/C16+C18] (ACMG) (PDF Document 172 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.

UT ACT Sheet for CPT I (CO/C16+C18) (ACMG) (PDF Document 123 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.

Services for Patients & Families in Utah (UT)

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.

Helpful Articles

PubMed search for CPT1 deficiency, last 15 years.

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;142C(2):77-85. PubMed abstract / Full Text

Authors & Reviewers

Initial publication: March 2007; last update/revision: June 2012
Current Authors and Reviewers:
Author: Nicola Longo, MD, Ph.D.
Reviewer: Kimberly Hart, MS, LCGC

Page Bibliography

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