CYP2D6*52 is assigned decreased function with an activity value of 0.25 based on limited evidence. Studies found CYP2D6*52 demonstrated decreased enzyme activity compared to wildtype with tamoxifen, bufuralol, dextromethorphan, and primaquine substrates (19364831, 23897164, 24647041, 30366777). This allele has 100C>T (the *10 SNP), 3854G>A (E410K) which we believe does not change function and 4181G>C (*2 SNP) which we also believe is benign. Therefore, consensus among experts was decreased function with limited evidence.