CYP2C9*27 is assigned uncertain function due to inadequate evidence. One subject with CYP2C9 *1/*27 genotype exhibited similar clearance compared to wildtype subjects based on tolbutamide plasma concentrations after one 500mg dose (25614704). In vitro studies showed conflicting results with CYP2C9*27 exhibiting enzyme activity ranging from decreased to increased compared to wildtype with various substrates (24118918, 23844998, 25476996, 25832633, 24077631, 25144335, 25951663, 23752738, 16788382, 25884291, 25614704, 25924705, 27163851, 25142737). Consensus was not achieved among experts and therefore uncertain function was assigned.