CYP2C19*38 was set as reference allele as this allele matches the human genome CYP2C19 Reference sequence LRG_584 / NG_008384.3. The RefSeq (LRG_584 / NG_008384.3) has 80161A while many of star alleles, including all *1 suballeles have 80161G. Thus, the CYP2C19*1 core allele is defined by one amino acid (I331V), while the *38 core allele definition does not have any amino acid changes.