CYP2C19*24 is assigned no function based on limited evidence. In vitro studies found CYP2C19*24 demonstrated nondetectable enzyme activity compared to wildtype with mephenytoin, clopidogrel, and omeprazole substrates (25001882, 27578295, 31713493). Additionally, CYP2C19*24 had less holoprotein compared to wildtype suggesting the protein is less stable resulting in little to no enzyme activity (27578295). Therefore, consensus among experts was no function based on limited evidence as it was determined the phenotypes containing this allele would be clinically distinct from phenotypes comprising normal function and decreased function alleles.