BlueCross BlueShield of Tennessee Medical Policy Manual

Cytochrome p450 Genotyping

Does Not Apply to Commercial Genetic Testing Program effective 6/1/2018


The cytochrome P450 (CYP450) family is a major subset of all drug-metabolizing enzymes. Several CYP450 enzymes are involved in the metabolism of a significant proportion of currently administered drugs. CYP2D6 metabolizes approximately 25% of all clinically used medications (e.g., dextromethorphan, beta blockers, antiarrhythmics, antidepressants and morphine derivatives). CYP450 enzyme genes can have distinct variations which can affect individual capability to metabolize specific drugs. CYP450 genotyping has been proposed as a way to direct early selection of the most effective drug or dose to avoid significant adverse events and speed the process of achieving a therapeutic dose.

Diagnostic genotyping tests for certain CYP450 enzymes are available. Several testing kits for CYP450 genotyping have been cleared by FDA. Test kits specific for the CTP2D6 include the AmpliChip® (33 CYP2D6 alleles) and the xTAG® CYP2D6 kit.

Test kits for CYP2C19 include the INFINITI™ CYP2C19 Assay, the Verigene CYP2C19 Nucleic Acid Test, and the Spartan RX® CYP2C19 testing system. Several manufacturers market diagnostic panel tests for genotyping that include multiple CYP450 genes, such as the YouScript Panel (CYP2D6, CYP2C19, CYP2C9, VKORC1, CYP3A4, and CYP3A5). Other panel tests include both CYP450 and other non-CYP450 genes involved in drug metabolism, such as the PersonaGene Genetic Panels.





Individuals with genetic variants of cytochrome P450 have a decreased ability to metabolize clopidogrel, but the impact on clinically meaningful outcomes is uncertain. While genotyping appears in some studies to be helpful in identifying individuals at higher risk of treatment failure and may be useful in selected individuals, more information is needed to refine optimal use of testing and to better understand the relative merit of management options.


Ahern, T., Hertz, D., Damkier, P., Eilertsen, B., Hamilton-Dutoit, S., Rae, J., et al. (2017). Cytochrome P-450 2D6 (CYP2D6) genotype and breast cancer recurrence in tamoxifen-treated patients: evaluating the importance of loss of heterozygosity. American Journal of Epidemiology, 185 (2), 75-85. Abstract retrieved November 20, 2017 from PubMed database.

American College of Cardiology Foundation/American Heart Association. (2012). 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction. Retrieved February 2, 2016 from

American College of Cardiology Foundation/American Heart Association. (2010). ACCF/AHA clopidogrel clinical alert: approaches to the FDA “boxed warning”. Retrieved September 27, 2012 from

BlueCross BlueShield Association.  Evidence Positioning System. (8:2020). Genotype-guided tamoxifen treatment (2.04.51). Retrieved April 23, 2021 from (62 articles and/or guidelines reviewed)

BlueCross BlueShield Association. Evidence Positioning System. (7:2020). Cytochrome p450 genotype-guided treatment strategy (2.04.38). Retrieved July 13, 2020 from (23 articles and/or guidelines reviewed)

BlueCross BlueShield Association. Evidence Positioning System. (8:2020). Genetic testing for diagnosis and management of mental health conditions. (2.04.110). Retrieved April 23, 2021 from (34 articles and/or guidelines reviewed)

Bykov, K., Schneeweiss, S., Glynn, R., Mittleman, M., Bates, D., & Gagne, J. (2017). Updating the evidence of the interaction between clopidogrel and CYP2C19-inhibiting selective serotonin reuptake inhibitors: a cohort study and meta-analysis. Drug Safety, 40 (10), 923-932. Abstract retrieved November 20, 2017 from PubMed database.

Drögemöller, B., Wright, G.E.B., Shih, J., Monzon, J.G., Gelmon, K.A., Ross, C.J.D., et al. (2019). Breast Cancer Research and Treatment, 173 (3), 521-532. Abstract retrieved October 8, 2019 from PubMed database.

Huang, B., Cui, D., & Zhao, X. (2017). Effect of cytochrome P450 2C19*17 allelic variant on cardiovascular and cerebrovascular outcomes in clopidogrel-treated patients: a systematic review and meta-analysis. Journal of Research in Medical Sciences, 22, 109. (Level 1 evidence)

National Comprehensive Cancer Network. (2021, March). NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®). Breast cancer. V 3.2021. Retrieved April 23, 2021 from the National Comprehensive Cancer Network.

Prapitpaiboon, H., Mahachai, V., & Vilaichone, R. (2015). High efficacy of levofloxacin-dexlansoprazole-based quadruple therapy as a first line treatment for helicobacter pylori eradication in Thailand. Asian Pacific Journal Cancer of Cancer Prevention, 16 (10), 4353-4356. Abstract retrieved March 16, 2016 from PubMed database

Xi, Z., Fang, F., Wang, J., AlHelal, J., Zhou, Y., & Liu, W. (2019). CYP2C19 genotype and adverse cardiovascular outcomes after stent implantation in clopidogrel-treated Asian populations: a systematic review and meta-analysis. Platelets, 30 (2), 229-240. Abstract retrieved October 8, 2019 from PubMed database.




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