Pharmacogenetics studies the genetic basis of efficacy and tolerance of medications and the inter-individual differences in response to drugs.


Active ingredients of medications react with certain target structures. The interaction with these structures is decisive for efficacy and tolerance of a medication. Target structures are usually either proteins or are influenced by proteins.

Fig. 1 Example of relevance of pharmacogenetics. The enzyme TPMT inactivates the drug thiopurine. Variants of the gene TPMT result in reduced activity of TPMT. As a consequence thiopurine is either not or only very slowly inactivated. This results in accumulation of thiopurine in the body and in undesired side-effects.


Structure and function of a protein thus depend on its genetic blueprint. Variants of this blueprint, i.e. the genetic sequence, can cause changes in structure and function of the protein.


This can result in increased or reduced efficacy or in complete inefficacy of a drug. Fig. 1 gives an example.


Several genetic variants are known that are relevant to the action of medications. These variants can be considered when prescribing relevant medications.