Reference Interval:
By report
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| Interpretive Data: |
Background Information for Cytochrome P450 2C19 (CYP2C19) 9 Mutations:
Characteristics: Impaired drug metabolism causing adverse drug reactions or lack of drug response. Drugs metabolized by CYP2C19 include clopidogrel, S-mephenytoin, diazepam, R-warfarin, some antidepressants (eg, citalopram, amitriptyline, clomipramine), proton pump inhibitors (eg, omeprazole, lansoprazole), and antimalarials (eg, chloroguanide).
Inheritance: Autosomal recessive.
Cause: CYP2C19 allelic variants.
Incidence of Poor Metabolizer Phenotype: 4 percent of Caucasians, 5 percent of African Americans, and up to 25 percent of Asians.
Penetrance: Drug dependant.
Clinical Sensitivity: 99 and 87 percent of pathogenic allelic variants detected in Asians and Caucasians respectively; sensitivity is unknown in other ethnicities.
Methodology: PCR and Detection Primer Extension.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Only the targeted CYP2C19 allelic variants will be detected. Additional allelic variants in CYP2C19 or other genes will not be detected. Rare diagnostic errors can occur due to primer site mutations. Mutation detection is not a substitute for therapeutic drug monitoring. Non-genetic factors may also affect drug metabolism.
References: Overview of CYP's (www.anaesthestist.com); nomenclature of CYP alleles (www.cypalleles.ki.se/); drug substrates/inhibitors/inducers for CYP (http://medicine.inpui.edu/flockhart).
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
See Compliance Statement C: www.aruplab.com/CS
| Allelic Variants Tested
| | Allele Designation
| Nucleotide Change
| Mutation Effect
| Predicted Enzyme Activity
| | *2
| c.681 G>A
| Splicing defect
| Non-functional
| | *3
| c.636 G>A
| New stop codon
| Non-functional
| | *4
| c.1 A>G
| Loss of initiation codon
| Non-functional
| | *6
| c.395G>A
| R132Q
| Non-functional
| | *7
| IVS5+2T>A
| Splicing defect
| Non-functional
| | *8
| c.358T>C
| W120R
| Non-functional
| | *9
| c.431G>A
| R114H
| Decreased function
| | *10
| c.680C>T
| P227L
| Decreased function
| | *17
| c.991A>G
| Increased gene transcription
| Increased function
| |
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| CPT Code(s): |
81225
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Cross References: |
Amitriptyline ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Clopidogrel ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Cytochrome P450 2C19 Genotype by Sequencing Analysis, Saliva (Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Elavil ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Escitalopram ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Lexapro ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Nolvadex ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Plavix ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
, Tamoxifen ( Cytochrome P450 2C19 (CYP2C19) 9 Mutations)
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