CYP2D6*49 is assigned decreased function based on limited evidence. Subjects with CYP2D6 *1/*49 genotypes demonstrated decreased dextromethorphan metabolism compared to wildtype subjects and subjects with CYP2D6 *10/*49 genotype demonstrated decreased dextromethorphan metabolism compared to subjects with CYP2D6 *1/*10 genotype (19364831). Multiple in vitro studies found CYP2D6*49 had decreased enzyme activity compared to wildtype with multiple substrates (18784265, 19158312, 24647041, 30366777). Therefore, consensus among experts was decreased function with an activity value of 0.5 based on limited evidence.