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The Claim

The CYP2C19 gene has high genetic variability with 39 possible alleles that influence the rate of medication metabolism.

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The Short Version

The claim is broadly accurate: CYP2C19 is highly variable genetically, and that variation can change how quickly certain medicines are metabolized. The main caveat is that “39 alleles” is not a settled, timeless number; authoritative sources report slightly different counts depending on date and counting method. The practical point about variability affecting drug response is well supported.

Caveats

  • The exact figure of 39 is a time-specific snapshot; other authoritative sources report 37 or more than 35 CYP2C19 variants.
  • The claim treats alleles, haplotypes, and star alleles as interchangeable, which is slightly imprecise in technical genetics usage.
  • Not every CYP2C19 variant has the same clinical impact; the strongest evidence concerns specific variants used to assign metabolizer status.

The Receipts

  1. Pharmacogenomics of CYP2C19 — Knowledge Hub

    Genomics Education Programme (NHS)

  2. 2022 Update – Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2C19 and Clopidogrel

    Clinical Pharmacology & Therapeutics (CPIC clopidogrel update PDF)

  3. PharmVar GeneFocus: CYP2C19

    PubMed (NIH)

  4. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Proton Pump Inhibitor Therapy and CYP2C19 Genotype

    Clinical Pharmacology & Therapeutics (CPIC PPI guideline PDF)

  5. Clinical Pharmacogenetics Implementation Consortium (CPIC): Gene-Specific Information Tables for CYP2C19

    Clinical Pharmacology & Therapeutics

  6. PharmVar GeneFocus: CYP2C19

    Clinical Pharmacology & Therapeutics (Wiley)

  7. From genes to drugs: CYP2C19 and pharmacogenetics in clinical practice

    PubMed Central

  8. CYP2C19 cytochrome P450 family 2 subfamily C member 19

    NCBI Gene

  9. CPIC Guidelines for CYP2C19 and Clopidogrel (2013 Scott et al.)

    Clinical Pharmacology & Therapeutics (CPIC – archived guideline)

  10. PharmVar GeneFocus: CYP2C19

    IU Indianapolis ScholarWorks

+ 14 more sources — see the full list on Lenz

Filed Under

CYP2C19

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