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Cytochrome P450 3A5 Genotyping, CYP3A5, 2 Variants
2012740
Ordering Recommendation

• Assess genetic risk of abnormal drug metabolism for drugs metabolized by CYP3A5.
• May aid in drug selection and dose planning for drugs metabolized by CYP3A5.

Mnemonic
CYP3A5
Methodology
Polymerase Chain Reaction/Fluorescence Monitoring
Performed
Mon, Thu
Reported
5-10 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
 
Collect
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL) 
Storage/Transport Temperature
Refrigerated. 
Unacceptable Conditions
Plasma or serum. Heparinized specimens. 
Remarks
 
Stability
Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month 
Reference Interval
By report
Interpretive Data
Background Information for Cytochrome P450 3A5 Genotyping, CYP3A5, 2 Variants:
Characteristics:
The cytochrome P450 (CYP) 3A subfamily of enzymes is involved in metabolism of many drugs such as immunosuppressants, antibiotics, antivirals, benzodiazepines, and steroids. Nonfunctional variants of CYP3A5 are common in some populations, preventing expression and function of the CYP3A5 enzyme, which will influence pharmacokinetics of CYP3A5 substrates, and may predict non-standard dose requirements.
Inheritance:
Autosomal co-dominant.
Cause:
CYP3A5 gene variants result in enzyme deficiency.
Variants Tested:
CYP3A5 non-functional alleles: *3 (rs776746, c.6986A>G), *6 (rs10264272, c.14690G>A).
Negative: No variants detected is predictive of *1 functional alleles and normal CYP3A5 enzyme activity. (Variants are numbered according to NG_007938.1 transcript)
Allele Frequencies:
CYP3A5*3: African 29.8 percent, Asian 74.2 percent, Caucasian 92.1 percent, Latin American 76.5 percent, Middle Eastern 88.1 percent
CYP3A5*6: African 17.2 percent, Asian 0.1 percent, Caucasian 0.1 percent, Latin American 3.7 percent, Middle Eastern 1.9 percent
CYP3A5*7: African 7.7 percent, Asian 0 percent, Caucasian 0 percent, Latin American 2.5 percent, Middle Eastern 0.2 percent
Clinical Sensitivity: Drug-dependent.
Methodology:
Polymerase chain reaction(PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Only the targeted CYP3A5 variants will be detected by this panel. Diagnostic errors can occur due to rare sequence variations. Many CYP3A substrates are also metabolized by CYP3A4, for which clinically relevant genetic variation is not recognized to be common. Risk of therapeutic failure or adverse reactions with CYP3A5 substrates may be affected by genetic and non-genetic factors that are not detected by this test. This result does not replace the need for therapeutic drug or clinical monitoring.

Compliance Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing. Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Note
CPT Code(s)
81401
Components
Component Test Code*Component Chart NameLOINC
2012741CYP3A5 Specimen
2012742CYP3A5 Genotype
2012743CYP3A5 Phenotype
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • CYP3A4