CYP2C19*17 is assigned increased function based on strong evidence in homozygous and heterozygous subjects. Subjects with CYP2C19 *1/*17 and CYP2C19 *17/*17 genotype demonstrated increased omeprazole metabolism compared to wildtype subjects based on plasma metabolite measurements. The predicted AUC of omeprazole in CYP2C19*17/*17 patients was 63% of the predicted AUC in wildtype subjects. Additionally, in a separate population, CYP2C19*17/*17 subjects demonstrated increased mephenytoin metabolism compared to wildtype and CYP2C19 *1/*17 subjects. A murine study found increased gene transcription of CYP2C19*17 likely results in the observed increased enzyme activity (16413245). CYP2C19 *17/*17 patients taking escitalopram had 42% serum escitalopram concentrations compared to wildtype (17625515). Also, in adolescents with generalized anxiety disorder, patients with *4/*17 or *17/*17 had lower AUC/CMAX compared to normal (*1/*1) and poor metabolizers and expected differences in the ratios of s-citalopram to its metabolite, desmethylcitalopram (PMID 32857933). Additionally, CYP2C19 *1/*17 and *17/*17 carriers in naturalistically studied depressed adults had 10% and 20% lower serum concentration compared to CYP2C19 NMs (29325448). In healthy adults, *17/*17 was associated with lower sertraline AUC vs normal metabolizers (29136336), although in a separate study involving more than 1200 patients, the CYP2C19*17 allele was associated with 8% lower serum concentration compared to NMs (31649299). CYP2C19 *17/*17 patients taking clopidogrel had lower ADP induced platelet aggregation likely as a result of increased clopidogrel metabolism to its active metabolite compared to wildtype and CYP2C19 *1/*17 patients (20083681). Therefore, consensus among experts was increased function based on strong evidence.