Table 4.

Assignment of likely TPMT Phenotype based on Genotype (CPIC, 2018)

Likely phenotypeaGenotypeExamples of diplotype
Normal metabolizerAn individual with 2 normal function alleles*1/*1
Intermediate metabolizerAn individual with one normal function allele PLUS one no function allele*1/*2, *1/*3A, *1/*3B, *1/*3C, *1/*4
Possible intermediate metabolizerAn individual with one uncertain/unknown function allele PLUS one no function allele*2/*8, *3A/*7
Poor metabolizerAn individual with 2 no function alleles*3A/*3A, *2/*3A, *3A/*3C, *3C/*4,*2/*3C, *3A/*4
IndeterminateAn individual with 2 uncertain/unknown function alleles
OR
one normal function allele plus one uncertain allele function allele		*6/*8
*1/*8

TPMT, thiopurine methyltransferase; NUDT15, Nudix (Nucleoside Diphosphate Linked Moiety X)-Type Motif 15

a

See TPMT and NUDT15 Frequency Table and Diplotype-Phenotype Table (2). for estimates of phenotype frequencies among different ethnic/geographic groups and for a more comprehensive list of predicted metabolizer phenotypes.

This CPIC table is adapted from (2).

From: Thioguanine Therapy and TPMT and NUDT15 Genotype

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Pratt VM, Scott SA, Pirmohamed M, et al., editors.
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