CYP2D6*7 is assigned no function based on limited evidence. CYP2D6*7 was first described in subjects demonstrating decreased sparteine metabolism (7845481). Two in vitro studies found CYP2D6*7 had nondetectable or markedly decreased enzyme activity compared to wildtype with tamoxifen, bufuralol, dextromethorphan, and primaquine substrates (24647041, 30366777). CYP2D6*7 is defined by an amino substitution near the active site disrupting protein folding and resulting in a nonfunctional enzyme based on computational analysis (7845481). 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.