CYP2C19*16 is assigned normal function based on limited evidence. A subject with CYP2C19 *2/*16 genotype demonstrated decreased mephobarbital excretion compared to heterozygous CYP2C19 *2 or CYP2C19*3 subjects but greater mephobarbital excretion compared to subjects carrying two no function alleles based on urine metabolites after a 200mg dose (15499191). Two in vitro studies using different cell systems found CYP2C19*16 had nondetectable or decreased enzyme activity compared to wildtype with mephenytoin, omeprazole, and clopidogrel substrates (25001882, 21325430). Another study found CYP2C19*16 exhibited significantly reduced catalytic activities compared with CYP2C19*1 across multiple substrates (21692664).Therefore, consensus among experts was decreased function based on limited evidence as it was determined the phenotypes containing this allele would be clinically distinct from phenotypes comprising normal function alleles.