Despite the name, pharmacogenomics studies are not genetic. In fact, these studies can only detect polymorphisms in the genes that make up the CYP enzyme. That’s why genetic testing is also called genotyping. Here’s a guide to the testing process.
CYP Polymorphisms
There are many benefits to pharmacogenetic testing for CYP polymorphisms. This genetic variation can influence hepatic clearance and plasma concentration of drugs. Additionally, it may influence the elimination of half-life. Patients with the heterozygous genotype of this gene carry two copies of the reduced-function allele.
As a result, these patients would be considered intermediate metabolizers. In addition, studies of CYP2D6 metabolism (www.ncbi.nlm.nih.gov) have found no significant association between genotype and breast cancer-related health outcomes. Nevertheless, commercial pharmacogenetic testing panels have been developed. These include Oncotype Dx(r) and MammaPrint(r).
Despite the lack of high-level recommendations, these studies may be valuable tools in the individualization of chemotherapy for patients with cancer. Despite this research, more research is needed to assess the cost-effectiveness of CYP testing for schizophrenia. Currently, there are only a handful of studies that have shown that CYP polymorphisms influence drug effectiveness in patients.
These studies also report high heterogeneity in outcome measures, methods, and patient populations. In addition to this, the studies also found a positive association between CYP2D6 genotype and the risk of developing schizophrenia. CYP2D6 is a major pharmacogenetic marker for schizophrenia. The gene is closely related to CYP2C19 and shows similar polymorphism.
Although its role in psychotropic drug biotransformation is minor, it should be genotyped. It may affect fluoxetine’s CYP2D6 metabolism, but the clinical effect of this is unknown. CYP1D6 genotyping is a useful tool in the development of new drugs for schizophrenia. Another study reported that CYP2C19*17 polymorphism is associated with an increased risk of major cardiovascular events.
However, the study did not show a causal association between carriers of the two LOF alleles and bleeding events. These results are consistent with other research. However, more research is needed to determine whether such polymorphisms have any benefits. So far, these polymorphisms may benefit from genetic testing.
A recent study analyzed a small number of patients for two CYP2C9*1 alleles. It found that patients carrying both wild-type alleles have a phenotype of normal metabolizer. The results were interpreted according to the patient’s genotype. This genetic variant has the potential to improve drug development for a variety of conditions, including cancer, pain management, and psychiatric disorders.
CYP Genotyping
CYP genotyping is a growing field that reveals the genetic basis for drug responses. Although the field has gained in acceptance and popularity, its use in clinical practice remains limited. The purpose of this study was to obtain a systematic overview of CYP2D6 genotyping results. In addition, this research provided a basis for further investigation of the use of CYP genotyping in clinical practice.
There are two types of CYP1A2 genes, CYP1A2*1B and CYP1A2*1F, which exhibits normal or reduced functions. CYP1A2*1B and *1D are inducible while CYP1A2*1F expresses a hyper-inducible phenotype in response to an inducer. These studies have several advantages. For example, CYP2D6 genotypes that have one non-functional allele can be translated to predicted phenotypes of the intermediate metabolizer of this drug.
Additionally, the results of CYP2D6 genotyping are used to improve drug prescriptions, as well as monitor adverse effects. The study also helps doctors customize patient care by offering a comprehensive pharmacogenetics panel for many commonly prescribed psychiatric drugs.
This genotype analysis is considered to be an essential test if they are taking high doses of codeine or have high risk factors. Moreover, pharmacogenetic tests for CYP genotypes are highly useful in detecting alterations in the enzyme that helps the body process drugs. For example, patients who take codeine must undergo CYP2D6 genotyping to monitor their drug response.
Cytochrome P450 genes are responsible for the metabolism of drugs. Variations in the CYP gene cause variation in drug response. The most important CYP gene, CYP2D6, plays a vital role in therapies for rare diseases. It is a gene that is often associated with reduced drug clearance.
The gene’s location is critical for drug metabolization, as it carries a significant impact on a patient’s drug response. The Dutch Pharmacogenetics Working Group (DPWG) started a project in 2005 to include pharmacotherapeutic recommendations in an electronic healthcare database.
Then, an alert system was developed for drugs prescribed to patients with a particular genotype that need immediate action. The system generates alerts and displays a short text on a specific drug that is associated with the CYP gene. The system also summarizes the clinical effects of a particular gene and drug interaction.
CPIC guidelines for pharmacogenetic testing are intended to guide clinicians in optimizing their drug therapies. They emphasize how genetic test results should be used and assume that clinical high-throughput genotyping and pre-prescription genotyping will become more widespread.
