Pharmacogene: CYP2C19 
Type of pharmacogene: Pharmacokinetic

CYP2C19 codes for the drug-metabolizing enzyme CYP2C19. This enzyme is responsible for metabolizing approximately eight percent (8%) of medications. Variants of this pharmacogene may affect drug metabolism of substrate drugs.

Pharmacogene Variant of the Week (PVOW 11_29_2017): CYP2C19*8

Reference single nucleotide polymorphism number: rs41291556  

DNA base change: c.358T>C  

Pharmacogene function as compared to normal function: No function

Pharmacogene product: CYP2C19 drug metabolizing enzyme

Pharmacogene product activity as compared to normal activity: None

General Conceptual Pharmacogene Variant Information

CYP2C19*8 Imparts:

Increased drug exposure

- Higher maximum concentration

- Increased area under the curve (AUC)

- Longer half-life

Note: For a prodrug, less of the active drug will be formed.

Drug Exposure Plot

Note: "No" or "decreased" function/activity shown in relative terms.

Conceptual statement 1: Notwithstanding other variables, individuals with one (heterozygous) or two (homozygous) copies of this pharmacogene variant will likely have decreased drug metabolism of an administered active drug, with increased exposure and potential increased risk of an adverse drug reaction.

Conceptual statement 2: Notwithstanding other variables, individuals with one (heterozygous) or two (homozygous) copies of this pharmacogene variant will likely have decreased drug metabolism of an administered prodrug, with decreased exposure to the active drug and potential increased risk of drug inefficacy.

The reader is directed to https://www.pharmgkb.org/haplotype/PA165816524