Table 2.
Method Used to Predict Drug Metabolizer Phenotype for CYP2C9, CYP2C19, and CYP2D6
| Predicted drug metabolizer phenotype | Actional PGx variant(s) | CYP2C9 | CYP2C19 |
CYP2D6 |
|
|---|---|---|---|---|---|
| Without gene duplication | With gene duplication | ||||
| UM | Yes | NA | Two increased activity alleles | Two increased activity alleles | Three normal and/or increased activity alleles |
| EM to UM | Yes | NA | Combination of 1 normal activity allele with 1 increased activity allele | Combination of 1 normal activity allele with 1 increased activity allele | Combination of 2 normal alleles with 1 decreased activity allele |
| EM | No | Two normal activity alleles | Two normal activity alleles | Two normal activity alleles; a combination of 1 increased activity allele with 1 decreased allele | Combination of 2 normal alleles with 1 null allele; a combination of 1 normal allele with 2 decreased activity alleles |
| IM to EM | Yes | Combination of 1 normal activity allele with 1 decreased activity allele | Combination of 1 increased activity allele with 1 null allele; a combination of 1 normal activity allele and a decreased activity allele | Combination of 1 normal activity allele with 1 decreased activity allele; a combination of 1 increased activity with 1 null allele | One increased activity allele with 2 null alleles, 3 decreased activity alleles |
| IM | Yes | Two decreased activity alleles; a combination of 1 normal activity allele with 1 null activity allele | Two decreased activity alleles; a combination of 1 normal activity allele with a null allele | One normal activity allele with 1 null activity allele; 2 decreased activity alleles | One normal allele with 2 or more null alleles, 2 decreased activity alleles with 1 null allele. |
| PM to IM | Yes | Combination of 1 decreased activity allele with 1 null allele | Combination of 1 decreased activity allele with 1 null allele | Combination of 1 decreased activity allele with 1 null allele | One decreased activity allele with 2 null alleles |
| PM | Yes | Two null alleles | Two null alleles | Two null alleles | Only null alleles detected |
See Table 1 for individual allele functions for these genes.
EM, extensive metabolizer; IM, intermediated metabolizer; NA, not applicable; PM, poor metabolizer; UM, ultrarapid metabolizer.