CYP2C19*13 is assigned normal function based on limited evidence. Three in vitro studies using different cell systems found CYP2C19*13 demonstrated similar enzyme activity compared to wildtype with mephenytoin, omeprazole, clopidogrel and other substrates (12464799, 21325430, 25001882, 21692664). Therefore, consensus among experts was normal function based on limited evidence as it was determined the phenotypes containing this allele would be clinically similar to phenotypes comprising normal function alleles.