Table 2.

CPIC (2016). Assignment of CYP2C19 Phenotypes.

PhenotypeGenotypeExamples of diplotypes
CYP2C19 ultrarapid metabolizer
(approximately 2–5% of individuals)a		An individual who has 2 increased function alleles *17/*17
CYP2C19 rapid metabolizer
(approximately 2–30% of individuals)		An individual who has one normal function allele and one increased function allele *1/*17
CYP2C19 normal metabolizer
(approximately 35–50% of individuals)		An individual who has 2 normal function alleles *1/*1
CYP2C19 intermediate metabolizer
(approximately 18–45% of individuals)		An individual who has one normal function allele and one no function allele, or one no function allele and one increased function allele *1/*2
*1/*3
*2/*17b
CYP2C19 poor metabolizer
(approximately 2–15% of individuals)		An individual who has 2 no function alleles *2/*2
*2/*3
*3/*3
a

CYP2C19 metabolizer status frequencies are based on average multi-ethnic frequencies. See the CYP2C19 Frequency Tables for population-specific allele and phenotype frequencies (17).

b

The predicted metabolizer phenotype for the*2/*17 genotype is a provisional classification. The currently available evidence indicates that the CYP2C19*17 increased function allele is unable to completely compensate for the CYP2C19*2 no function allele.

This CPIC table is adapted from (17).

From: Clobazam Therapy and CYP2C19 Genotype

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