Tandem mass spectrometric measurement of serum/plasma acylcarnitines can be used as an initial screening test. The finding suggestive of a defect in mitochondrial beta-oxidation (and thus suspect for CPT II deficiency) is an elevation of C12 to C18 acylcarnitines, notably of C16 and C18:1. Diagnosis can be made by detection of reduced CPT enzyme activity, however, measured enzyme activity is dependent on assay conditions, which have not been standardized, making comparisons of published data from different laboratories difficult. Molecular genetic testing of CPT2 (1p32), the only gene known to be associated with CPT II deficiency, provides additional means for noninvasive, rapid, and specific diagnosis. Carriers can be detected by measuring enzyme activity in muscle homogenates; no data regarding the use of MS/MS for carrier detection are available. When causative mutations are known, carrier testing should rely on molecular genetic methods.
Sequencing of the CPT2 gene is recommended after a biochemical analysis consistent with CPT II, and provides a complementary method to confirm the presence of mutations in a proband, identify carriers among the proband's relatives, and provide prenatal diagnosis in families with known mutations.
For patients with mutations not identified by full gene sequencing, a separate deletion/duplication assay is available using a targeted CGH array (EX).
- Confirmation of a clinical/biochemical diagnosis of CPT II.
- Carrier testing in adults with a family history of CPT II.
Analytical Sensitivity: ~99%
Submit only 1 of the following specimen types
Preferred specimen type: Whole Blood
Type: Whole Blood
Specimen Requirements:In EDTA (purple top) or ACD (yellow top) tube:
Infants (<2 years): 2-3 ml
Children (>2 years): 3-5 ml
Older Children & Adults: 5-10 ml
Specimen Collection and Shipping: Refrigerate until time of shipment. Ship sample within 5 days of collection at room temperature with overnight delivery.
Specimen Requirements:OrageneTM Saliva Collection kit (available through EGL) used according to manufacturer instructions.
Specimen Collection and Shipping: Store sample at room temperature. Ship sample within 5 days of collection at room temperature with overnight delivery.
- Acylcarnitine profile (AR).
- Custom diagnostic mutation analysis (KM) is available to family members if mutations are identified by sequencing.
- A deletion/duplication assay is available separately for individuals where mutations are not identified by sequence analysis. Refer to the test requisition or contact the laboratory for more information.
- Prenatal testing is available to couples who are confirmed carriers of mutations. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.