CYP2D6*129 is assigned no function based on limited evidence. CYP2D6*129 is defined by an premature stop codon predicted to yield truncated protein and thus be nonfunctional. One in vitro study demonstrated substantially decreased intrinsic clearance CLint (Vmax/Km) of 3.2% compared to *1 for tamoxifen N-desmethylation; no activity was detectable for dextromethorphan O-demethylation (32759992). Therefore, consensus among experts was no function with an activity value of 0 based on limited evidence.