Table 2.

2016 Assignment of CYP2D6 phenotypes by CPIC

PhenotypeActivity ScoreGenotypesExamples of diplotypes
CYP2D6 Ultrarapid metabolizer
(approximately 1-20% of patients)a		Greater than 2.0An individual carrying duplications of functional alleles (*1/*1)xN
(*1/*2)xN
(*2/*2)xN b
CYP2D6 Normal metabolizer
(approximately 72-88% of patients)		1.0 – 2.0cAn individual carrying two normal function alleles
or two decreased function alleles
or one normal and no function allele
or one normal function and decreased function allele
or combinations of duplicated alleles that result in an activity score of 1.0 to 2.0		 *1/*1
*1/*2
*2/*2
*1/*9
*1/*41
*41/*41
*1/*5
*1/*4
CYP2D6 Intermediate metabolizer
(approximately 1-13% of patients)		0.5An individual carrying one decreased function and one no function allele *4/*41
*5/*9
*4/*10
CYP2D6 Poor metabolizer
(approximately 1-10% of patients)		0An individual carrying two no function alleles *4/*4
*4/*4xN
*3/*4
*5/*5
*5/*6
a

For population-specific allele and phenotype frequencies, please see
b Where xN represents the number of CYP2D6 gene copies (N is 2 or more).
c Patients with an activity core of 1.0 may be classified as intermediate metabolizers by some reference laboratories.
For more information about activity scores, please see the Genetic Testing section.

This table has been adapted from Hicks J.K., Sangkuhl K., Swen J.J., Ellingrod V.L., Müller D.J., Shimoda K., Bishop J.R., Kharasch E.D., Skaar T.C., Gaedigk A., Dunnenberger H.M., Klein T.E., Caudle K.E. Clinical Pharmacogenetics Implementation Consortium Guideline (CPIC®) for CYP2D6 and CYP2C19 Genotypes and Dosing of Tricyclic Antidepressants: 2016 Update. Clinical pharmacology and therapeutics. 2016 Dec 20 [Epub ahead of print] (18).

From: Thioridazine Therapy and CYP2D6 Genotypes

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