Development of simplified and rapid detection assay for genetic polymorphisms influencing drug response and its clinical applications

Clinically important genetic polymorphisms influencing drug metabolism and drug response have typically been discovered on the basis of phenotypic differences among individuals from different populations. Routine genotyping before drug therapy may enable the identification of responders, nonresponders, or patients at increased risk of toxicity. Automated, high-throughput detecting methods for single-nucleotide polymorphisms (SNPs) are highly desirable in many clinical laboratories. The aim of this study is to develop a high-throughput genotyping method for detecting SNPs influencing drug response in the Japanese population. We have developed three real-time PCR assays for detecting SNPs in the human drug-metabolizing enzymes and drug targets. The assay for simultaneously detecting CYP2A6, CYP2B6, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP3A5, NAT2, TPMT, DPYD, UGT1A1, ALDH2, ADH2, MDR1, CETP, DCP-1, ADRB2, HTR2A, INPP1, SDF1, and mitochondrial DNA polymorphisms takes less than 1.5 h. With the clinical application of NAT2 genotyping, we found statistically significant difference between the incidence of adverse drug reactions (ADRs) and the NAT2 genotype. The incidence of the ADRs was significantly higher in the slow type than the in other two types, as 5 of the 6 patients were of the slowtype, and the other was the intermediatetype, while no patients of the rapidtype has developed any ADRs.