CYP2C19*25 is assigned decreased function based on limited in vitro and computational evidence. An in vitro study found CYP2C19*25 had decreased intrinsic clearance compared to wildtype with clopidogrel and mephenytoin, and omeprazole substrates (25001882, 31713493). A computational analysis of the Phe448Leu amino acid substitution in CYP2C19*25 predicted the change as deleterious. An examination of the structure showed the amino acid substitution, which is important for the heme-binding region, could disrupt the hydrophobic pocket in the region (19636337). 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.