CYP2D6*132 is assigned decreased function with an activity value of 0.25 due to limited literature describing function of this allele. One in vitro study demonstrated substantially decreased intrinsic clearance CLint (Vmax/Km) of 3.8% and 0.5% compared to *1 for tamoxifen N-desmethylation and dextromethorphan O-demethylation, respectively (32759992). The allele contains 100C>T and 4181G>C (present in *10) and 2819A>G. There are no data describing the consequence of 2819A>G; however, based on the function of *10 and the in vivo study, consensus among experts was decreased function due to limited evidence.