Technical advanceHigh-Quality Genotyping Data from Formalin-Fixed, Paraffin-Embedded Tissue on the Drug Metabolizing Enzymes and Transporters Plus Array

The Affymetrix Drug Metabolizing Enzymes and Transporters (DMET) Plus array covers 1936 markers in 231 genes involved in drug metabolism and transport. Blood- and saliva-derived DNA works well on the DMET array, but the utility of DNA from FFPE tissue has not been reported for this array. As the ability to use DNA from FFPE tissue on the array could open the potential for large retrospective sample collections, we examined the performance and reliability of FFPE-derived DNA on the DMET Plus array. Germline DNA isolated from archived normal FFPE tissue blocks stored for 3 to 19 years and matched blood or saliva from 16 patients with osteosarcoma were genotyped on the DMET Plus array. Concordance was assessed by calculating agreement and the κ-statistic. We observed high call rates for both the blood- or saliva-derived DNA samples (99.4%) and the FFPE-derived DNA samples (98.9%). Moreover, the concordance among the 16 blood- or saliva-derived DNA and FFPE DNA pairs was high (97.4%, κ = 0.915). This is the first study showing that DNA from normal FFPE tissue provides accurate and reliable genotypes on the DMET Plus array compared with blood- or saliva-derived DNA. This finding provides an opportunity for pharmacogenetic studies in diseases with high mortality rates and prevents a bias in studies where otherwise only alive patients can be included.