Ordering Recommendation

Assesses genetic risk of abnormal drug metabolism for substrates of CYP3A4 and/or CYP3A5. May aid in drug selection and dose planning for drugs metabolized by CYP3A4 and/or CYP3A5.

Mnemonic

3A4/3A5

Methodology

Polymerase Chain Reaction/Fluorescence Monitoring

Performed

Varies

Reported

5-10 days

New York DOH Approval Status

This test is New York DOH approved.

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. Specimens collected in sodium heparin or lithium heparin. Frozen specimens in glass collection tubes.

Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

By report

Interpretive Data

Background Information for CYP3A4 and CYP3A5:
Characteristics:
The cytochrome P450 (CYP) 3A subfamily of enzymes is involved in metabolism of many drugs. Variants in the genes that code for CYP3A4 and CYP3A5 may influence pharmacokinetics of CYP3A substrates, and may predict or explain non-standard dose requirements, therapeutic failure or adverse reactions.
Inheritance:
Autosomal codominant.
Cause:
CYP3A4 or CYP3A5 gene variants affect enzyme expression or activity.
Variants Tested:
 See the Additional Technical Information document.
Clinical Sensitivity:
Drug-dependent.
Methodology:
Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity:
Greater than 99 percent.
Limitations:
Only the targeted CYP3A4 and CYP3A5 variants will be detected by this panel, and assumptions about phase and content are made to assign alleles. Publicly available sources such as the www.pharmvar.org or www.pharmgkb.org provide guidance on phenotype predictions and allele frequencies. Diagnostic errors can occur due to rare sequence variations. Risk of therapeutic failure or adverse reactions with CYP3A 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.  

Please note the information contained in this report does not contain medication recommendations, and should not be interpreted as recommending any specific medications. Any dosage adjustments or other changes to medications should be evaluated in consultation with a medical provider. 

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Compliance Category

Laboratory Developed Test (LDT)

Note

Whole blood is the preferred specimen. Saliva samples that yield inadequate DNA quality and/or quantity will be reported as inconclusive if test performance does not meet laboratory-determined criteria for reporting.

Hotline History

N/A

CPT Codes

81230; 81231

Components

Component Test Code* Component Chart Name LOINC
3001519 3A4/3A5 Specimen 31208-2
3001520 CYP3A4 Genotype 81139-8
3001521 CYP3A5 Genotype 81140-6
3001522 3A4/3A5 Interpretation 50398-7
* 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

  • 3A4
  • 3A5
  • CYP3A4
  • CYP3A5
  • Cytochrome P450 3A4
  • Cytochrome P450 3A5
  • tacrolimus
CYP3A4 and CYP3A5