The variants included in the alleles are based on the PharmVar core alleles (for core allele definitions only, see https://www.pharmvar.org/gene/CYP2D6). In addition, variants that present in the core allele for one star allele but also present in some but not all suballeles of another star allele are included in the other star allele as ambiguous changes using the IUPAC nucleotide code (https://www.bioinformatics.org/sms/iupac.html), e.g. the *4 consensus allele includes a "R" being either G or A (positive strand) at the 100C>T (P34S) position since this variant is part of other core star alleles, e.g. *10, but is not part of the *4 core allele at PharmVar since it is not present in all *4 suballeles. These postions are represented in grey (G) in the Comparative Allele ViewEr (CAVE) tool at PharmVar. The g.42129130C>G position is an exception. The SNP by itself causes a synonymous change, therefore by itself the SNP would not be part of a core allele based on the core allele definition. However, in *29 and *70 the SNP is needed for the amino acid change and therefore part of the *29 and *70 core allele definition in PharmVar. To follow the above, "S" is added at the position for star alleles in which not all suballeles carry the SNP. In case all suballeles have the SNP "G" is added.