The ultimate goal in measuring CYP450 function or identifying polymorphisms is to predict effective therapeutic doses and responses in patients and avoid potential toxicities.
Polymorphisms are now reasonably easy to detect in clinical laboratories that perform molecular testing. They can be identified using allele-specific PCR, restriction digests, sequencing, hybridization assays, bead-based systems, microarrays, pyrosequencing, or other methods.
Although most clinical labs do not offer PGx testing, all major reference labs now provide this testing. Direct marketing to patients has also led to some external demand for these tests.
Most reference labs offer extended PGx profile panels. For example, a typical CYP2D6 profile measures about one dozen of this enzyme's most common and significant mutation sites, allowing for the detection of approximately 98% of the known CYP2D6 polymorphisms. The laboratory then generates a report advising the physician on the patient's drug metabolizing status. Some interpretive reports may even contain dosing suggestions for the patient.
Estimates show that 6–10% of the general population have a complete deficiency of CYP2D6, with the prevalence of mutations varying from <1% to as much as 21% within a given population.
