Table 1.
Assignment of Predicted CYP2C19 Phenotype Based on Genotype
| Predicted phenotype | Genotype | Examples of CYP2C19 diplotypesa |
|---|---|---|
| CYP2C19 ultrarapid metabolizer | An individual carrying two increased function alleles | *17/*17 |
| CYP2C19 rapid metabolizer | An individual carrying one normal function allele and one increased function allele | *1/*17 |
| CYP2C19 normal metabolizer | An individual carrying two normal function alleles | *1/*1 |
| CYP2C19 likely intermediate metabolizerb | An individual carrying one normal function allele and one decreased function allele or one increased function allele and one decreased function allele or two decreased function alleles | *1/*9, *9/*17, *9/*9 |
| CYP2C19 intermediate metabolizer | An individual carrying one normal function allele and one no function allele or one increased function allele and one no function allele | *1/*2, *1/*3, *2/*17, *3/*17 |
| CYP2C19 likely poor metabolizerb | An individual carrying one decreased function allele and one no function allele | *2/*9, *3/*9 |
| CYP2C19 poor metabolizer | An individual carrying two no function alleles | *2/*2, *3/*3, *2/*3 |
| Indeterminate | An individual carrying one or two uncertain function alleles | *1/*12, *2/*12, *12/*14 |
a
Please refer to the CYP2C19 Diplotype-Phenotype Table online for a complete list. For allele functions and population-specific allele and phenotype frequencies, please refer to the CYP2C19 Allele Functionality Table and the CYP2C19 Allele Frequency Table online (8, 9).
b
There are limited data to characterize the function of decreased function alleles.