Genotyping by allele-specific l-DNA-tagged PCR

We have developed a novel method for typing single-nucleotide polymorphisms (SNPs) that can be applicable to rapid screening. The method involves the fusion of two PCR techniques, allele-specific PCR (AS-PCR) and l-DNA-tagged PCR (LT-PCR), which enables us to label PCR products with sequence-defined tags of mirror-image DNA (l-DNA). PCR products were applied without any purification or denaturation steps to gold surfaces where complementary single-stranded l-DNA was immobilized, and the products were detected with surface plasmon resonance (SPR) imaging. We were able to clearly discriminate 3 genotypes at position 2677 of the MDR1 gene (G/G-homozygote, G/T-heterozygote, and T/T-homozygote) by comparing SPR difference images.