Substrate specificity of CYP2D6 genetic variants.

Genetic variation in the gene encoding CYP2D6 is used to guide drug prescribing in clinical practice. However, genetic variants in CYP2D6 show substrate-specific effects that are currently not accounted for. With a systematic literature, we retrieved 22 original studies describing experiments focusing on alleles (*1, *2, *10 and *17) and substrates. Allele activity (clearance of the allele of interest divided by the clearance of the wildtype) was extracted. The results support the hypothesis of the existence of substrate specificity of the *17-allele (higher debrisoquine clearance), a subtle effect of the *10-allele (lower dextromethorphan clearance) but no substrate-specific effect of the *2-allele. Although our results support substrate specificity, for most substrates data are too sparse and require further studies.