CYP2C9*2 is assigned decreased function based on definitive evidence in homozygous and heterozygous patients and in vitro experimental data. CYP2C9*2 has been studied for more than 20 years and its association with impaired function compared to wildtype is well-established (29283396, 20150829, 15637526). The phenotype for patients homozygous for the CYP2C9*2 variant was updated from poor metabolizer to intermediate metabolizer after reevaluation of prior and new evidence demonstrating CYP2C9*2 has more enzyme activity than CYP2C9*3, which results in in a similar phenotype for CYP2C9*1/*3 and CYP2C9 *2/*2 patients (12742136, 10413320, 27179628, 25775139, 19082874, 30088221), both of which can be distinguished from those homozygous for CYP2C9*3/*3. Therefore, consensus among experts was decreased function with an activity value of 0.5 based on definitive evidence.