Comparing Cytochrome P450 Variant Alleles Tested and Reported in Clinical Pharmacogenomic Testing Panels

Abstract

Specific Aims: To evaluate and describe the variability in cytochrome P450 genetic polymorphisms tested by laboratories offering pharmacogenomic (PGx) genotyping panels using website information and sample reports for various genetic panels. Methods: This was a descriptive study evaluating pharmacogenomic testing company websites for cytochrome P450 genetic polymorphisms. An information extraction form was developed to assess which genetic polymorphisms for CYPs 2C9, 2C19, 2D6, 3A4, and 3A5 were tested and reported for each PGx company website offering genotyping panels. Each student investigator completed an electronic copy of the extraction form for each PGx website to confirm consistency of findings. Main Results: Of the ten PGx allele panels that were reviewed, consistency varied greatly as CYP2C19 had the highest consistency frequency amongst the panels reviewed with 4 out of 11 alleles having concordance (36.4%), followed by CYP2D6 (23.7%), CYP3A5 (16.7%), CYP2C9 (12.5%) and CYP3A4 (0%). Conclusions: As the laboratories that offer PGx testing rapidly increases with the field of PGx, the consistency of reporting amongst companies is different. From the ten panels that were reviewed it can be concluded that each company is dissimilar in the alleles tested and reported. PGx testing is becoming widely used to safely personalize medication therapy for various medical disease states. Currently, the variation in testing panels make it difficult for clinicians to incorporate the results into clinical practice with confidence.