CYP2D6*15 is assigned no function based on limited evidence. CYP2D6*15 was first described in a subject demonstrating markedly decreased dextromethorphan and debrisoquine metabolism (8807669). CYP2D6*15 is defined by an amino acid insertion resulting in missense sequence and premature stop codon, yielding a truncated nonfunctional enzyme. Therefore, consensus among experts was no function with an activity value of 0 based on limited evidence as it was determined the phenotypes containing this allele would be clinically distinct from phenotypes comprising normal and decreased function alleles.