Digital versatile discs as platforms for multiplexed genotyping based on selective ligation and universal microarray detection

The development of a high-performance assay readout using integrated detectors is a current challenge in the implementation of DNA tests in diagnostic laboratories, particularly for supporting pharmacogenetic tests. A method for allelic discrimination, associated with single nucleotide polymorphisms (SNPs), is presented. Genomic DNA is extracted from blood and buccal swab samples. The procedure comprises fast multiplex ligation- dependent probe amplification, PCR amplification using universal primers and subsequent barcode hybridization. In this last step, each product is recognized by the specific probes immobilized on the surface of an optical disc. Assay results can be obtained with a disc reader. The optical sensing method in a DNA microarray format was optimized and evaluated for the simultaneous identification of 28 polymorphisms associated with psychiatric pharmacogenomics. The target biomarkers were located in the genes related to drug-metabolizing enzymes and drug transporters. The multiplexing capability and assay selectivity strongly depended on correct design (ligation probes, tails and barcodes). The discriminant analysis of reader outputs (spot intensities) led to patients being classified into different allelic populations. The obtained assignations correlated properly with the results provided by the reference technique (bead arrays), and the assay ended in an 8-fold shorter time using affordable equipment. The combination of a highly selective genotyping reaction as array-MLPA and the compact disc technology provides a reliable point-of-care approach. This genotyping tool is useful for the selection of personalized drug therapies in decentralized clinical laboratories.