CYP2C9*43 is assigned no function based on limited evidence in in vitro studies. Multiple in vitro studies found CYP2C9*43 demonstrated markedly decreased clearance compared to wildtype with various substrates (24077631, 24118918, 25142737, 25144335, 25476996, 25832633, 25884291, 25951663, 27163851, 23844998). 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 function or decreased function alleles.