CYP2C19*29 is assigned uncertain function due to inadequate evidence. In vitro studies found CYP2C19*29 demonstrated modest decreased enzyme activity compared to wildtype with mephenytoin, omeprazole, and voriconazole substrates (26153442, 30464555). One in vitro study found increased clearance relative to wild-type for nebivolol (29098786). Consensus was not achieved among experts as data were sparse and conflicting and it was not convincing the magnitude of decreased activity was clinically significant. Therefore, uncertain function was assigned.