Table 3.

Examples of the activity scores of CYP2D6. ^a CYP2D6*2 is currently considered to be a normal function allele by CPIC and DPWG; however, this function assignment has been challenged, and some laboratories report the CYP2D6*2 function differently. The function of this allele will be reassessed as additional data become available. ^b N is categorical and indicates the number of copy variants (e.g., *1 × 2, *1 × 3, etc.).

Activity Score	Alleles (Examples)	Type of Allele and Genotype
>2.25	*1/*1 × N, *1/*2 × N b*2 a/*2 × N b, *1 × 2/*9	Increased activity, Ultra rapid metabolizer
≤2.25 to ≥1.25	*1/*10, *1/*41, *1/*9, *1/*1, *1/*2, *2 × 2/*10	Wild-type, Normal metabolizer
>0 to <1.25	*4/*10, *4/*41, *10/*10, *10/*41, *41/*41, *1/*5	Reduced function, Intermediate metabolizer
0	*3/*4,*4/*4,*5/*5,*5/*6	Non-functional, Poor metabolizer