Validation of the performance of a comprehensive genotyping assay panel of single nucleotide polymorphisms in drug metabolism enzyme genes

A class of genes, known as drug metabolism enzymes (DMEs) are responsible for the metabolism and transport of drugs and other xenobiotics. Variation in DME genes most likely accounts for a proportion of the variability in drug response in humans, and may contribute to complex diseases such as cancer (Nebert DW, Dieter MZ. Pharmacology 2000;61:124-135). To date, assessing the extent of this variation has proven difficult, especially because of sequence paralogy issues that cause difficulty when attempting to genotype polymorphisms in very closely-related gene families (Murphy ME Pharmacogenomics 2000;1:115-123; Ingelman-Sundberg M. Drug Metab Rev 1999;31:449-459). We have developed and genotyped a panel of N = 2,325 individual TaqMan (R) genotyping assays for polymorphisms in > 200 DME genes; many of the variants in the panel are single nucleotide polymorphisms (SNPs) that are of known or putative function (e.g., missense, nonsense or frameshift). Using these assays, we have examined genetic variation among several groups of populations, including: 1) the two SNP500 Cancer population panels (http://snp500cancer.nci.nih.gov; last accessed: 11 December 2007); and 2) the panel used in the International HapMap Project panel (www.hapmap.org; last accessed: 11 December 2007). We have developed a comprehensive validation strategy to ensure reproducibility and accuracy of the assays and estimated minor allele frequencies. Here, we present the results of these analyses, which strongly suggest that this panel of DME assays are of extremely high quality and produce robust, accurate, and reproducible results.