Cytochrome P450 2D6 Deletion Genotyping Using Derivative Curve Analysis on the LightCycler

Cytochrome P450 2D6 (CYP2D6) is an isoenzyme of the cytochrome P450 super family that catalyzes the oxidative biotransformation of numerous exogenous compounds. These compounds include many commonly prescribed drugs such as antiarrhythmics, β-receptor blockers, neuroleptics, selective serotonin reuptake inhibitors and tricyclic antidepressants (1). Genetic polymorphism in CYP2D6 is common and can affect therapeutic response. Polymorphisms include single nucleotide polymorphisms (SNPs), gene deletions and duplications. When gene deletions or SNPs are present, drug clearance is impaired, resulting in possible accumulation and toxicity of the drug. When the gene is duplicated, a lack of therapeutic benefit may be seen due to rapid drug clearance. Poor metabolizers with impaired enzyme function comprise approximately 7% of Caucasians, 2% of African Americans and 1% of Asian populations (1–3). Individualized dosage based on the knowledge of genetic constitution can be used to improve drug therapy and decrease the incidence of adverse drug effects.