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Matrix Genomics

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Drug Metabolism - Liver Enzyme CYP2C19 ('two C nineteen')

CYP2C19 Activity

The forms of CYP2C19 that you have inherited are reported, along with your level of enzyme activity to process certain drugs, either rapid, extensive, intermediate or poor.

Eight nonfunctional forms of CYP2C19, and the ultrarapid *17 form, are evaluated. Buccal swabs ... blood not required. 5-day standard turnaround time.

Insurance may cover this test: CPT codes 1 X 83891, 2 X 83892, 1 X 83900, 3 X 83901, 7 X 83914, 1 X 83909, 1 X 83912, 1 X 83912-26

NPI 1467 7837 53

CYP2C19 is a key liver enzyme that effects treatment with many common medications.

The CYP2C19 gene encodes the CYP2C19 enzyme needed to activate & metabolize many common medications -- tamoxifen taken to prevent recurrence of breast cancer, clopidogrel taken to prevent heart attack and stroke, hormones estrogen & progesterone, anti-depressants amitriptyline & clomipramine, anti-ulcer proton pump inhibitors omeprazole (Losec, Prilosec), esomeprazole (Nexium), lansoprazole (Prevacid), anti-epileptics diazepam, phenytoin & phenobarbitone, and the anti-malarial drug proguanil.

There are a number of inherited forms of CYP2C19:

  • CYP2C19*1 is the common active form of the enzyme. CYP2C19*2 & *3 are inactive forms of the enzyme. Infrequent inactive forms are *4, *5, *6, *7, and *8.
  • EM: Persons who inherit *1 from both parents have normal enzyme activity, and are extensive metabolizers (EM).
  • IM: Persons who one inactive copy have reduced activity, and are intermediate metabolizers (IM).
  • PM: Persons who two inactive copies have little or no activity, and are poor metabolizers (PM).
  • Table 1 shows the frequency of extensive, intermediate and poor metabolizers in the population. Persons of Asian and African ancestry are more likely to be poor metabolizers.

Table 1. Frequency of extensive, intermediate, and poor metabolizers in the population.

Table 1. CYP2C19

  • UM: Several percent of the population has an extra active form called *17, one or two copies results in ultrarapid drug metabolism (UM).

    • Our test identifies the forms of CYP2C19 that you have inherited, and your level of enzyme CYP2C19 activity. This information may be very useful in selecting which drug is more likely to be useful and safe, and in adjusting drug dosage. Examples of how clinical outcomes vary according to the level of CYP2C19 activity are given here. No claim is made that all aspects of CYP2C19 metabolism are investigated. Discuss this information with your physician.