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OMIM: +124030
Gen: CYP2D6
Locus: 22q13.1

PHARMACOGENETICS OF TAMOXIFEN
(CYP2D6 GENE TEST)

Background

Tamoxifen, a molecule essentially prescribed for the treatment of breast cancer, is a pro-drug which must be activated by the enzyme CYP2D6 before becoming pharmacologically active. In post-menopausal women, CYP2D6 can become an indirect indicator of the after-effects of primary breast cancer being treated with tamoxifen.

CYP2D6 genotypes

Class Frequency Genotypes (examples) Commentary
Extensive metabolizer (EM) 92% *1*1, *1*4, *1*3 No sign of reduced CYP2D6 activity
Poor metabolizer
(PM)
8% *4*4, *4*6, *3*4 Strongly reduced CYP2D6 activity


The gene tests includes the most important non-functional CYP2D6 alleles (*3, *4, *6).


Indications for testing

  • Individuals starting tamoxifen therapy.




  • Literatur:
  • Punglia RS, Burstein HJ, Winer EP, Weeks JC. Pharmacogenomic variation of CYP2D6 and the choice of optimal adjuvant endocrine therapy for postmenopausal breast cancer: a modeling analysis. J Natl Cancer Inst. 2008;100:642-8.

  • Goetz MP, Kamal A, Ames MM. Tamoxifen pharmacogenomics: the role of CYP2D6 as a predictor of drug response. Clin Pharmacol Ther. 2008;83:160-6.