CYP2D6*2x≥3 is assigned increased function based on limited evidence. CYP2D6*2x≥3 was described in a family demonstrating increased enzyme activity based on urine metabolites with a debrisoquine substrate (7903454). Subjects with CYP2D6 gene duplications demonstrated increased enzyme activity with the greatest debrisoquine metabolism among all subjects (7616439, 8764380). Therefore, consensus among experts was increased function with an activity value of ≥3 based on limited evidence as it was determined the phenotypes containing this allele would be clinically distinct from phenotypes comprising normal function alleles.