Interpretive Handbook

Test 61121 :
Carnitine Palmitoyltransferase II Deficiency, Known Mutation

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal recessive disorder of long-chain fatty-acid oxidation. There are 3 distinct clinical phenotypes: a lethal neonatal form, an early-onset infantile form, and a late-onset adult myopathic form. The lethal neonatal and early-onset infantile forms are characterized by liver failure, cardiomyopathy, seizures, hypoketotic hypoglycemia, peripheral myopathy, and early death. The adult-onset myopathic form is the most common type and is characterized by exercise-induced muscle pain and weakness and may be associated with myoglobinuria. Males are more likely to be affected with the myopathic form than females.


Initial screening can be done with plasma acylcarnitines. Definitive diagnosis can be made by detection of reduced CPT enzyme activity. Mutations in the CPT2 gene are responsible for CPT II deficiency and sequencing of this gene is recommended after positive biochemical analysis.

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnostic confirmation of carnitine palmitoyltransferase II deficiency when familial mutations have been previously identified


Carrier screening of at-risk individuals when a mutation in the CPT2 gene has been identified in an affected family member

Interpretation Provides information to assist in interpretation of the test results

An interpretative report will be provided.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The identification of a disease-causing mutation in an affected family member is necessary before predictive testing for other family members can be offered. If a familial mutation has not been previously identified, order CTP2S / Carnitine Palmitoyltransferase II Deficiency, Full Gene Analysis.


Analysis is performed for the familial mutations provided only. This assay does not rule out the presence of other mutations within this gene or within other genes that may be associated with metabolic disease.  


Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Any error in the diagnosis or in the pedigree provided to us, including false-paternity, could lead to erroneous interpretation of results.


A previous bone marrow transplant from an allogenic donor will interfere with testing. Call Mayo Medical Laboratories for instructions for testing patients who have received a bone marrow transplant.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Bonnefont JP, Djouadi F, Prip-Buus C, et al: Carnitine palmitoyltransferases 1 and 2: biochemical, molecular and medical aspects. Mol Aspects Med 2004 Oct-Dec;25(5-6):495-520

2. Siguake E, Rakheja D, Kitson K, Bennet M: Carnitine palmitoyltransferase II deficiency: a clinical, biochemical, and molecular review. Lab Invest  2003 Nov;83(11):1543-1554