A comprehensive assay for targeted multiplex amplification of human DNA sequences

Abstract

We developed a robust and reproducible methodology to amplify human sequences in parallel for use in downstream multiplexed sequence analyses. We call the methodology SMART (Spacer Multiplex Amplification Reaction), and it is based, in part, on padlock probe technology. As a proof of principle, we used SMART technology to simultaneously amplify 485 human exons ranging from 100 to 500 bp from human genomic DNA. In multiple repetitions, >90% of the targets were successfully amplified with a high degree of uniformity, with 70% of targets falling within a 10-fold range and all products falling within a 100-fold range of each other in abundance. We used long padlock probes (LPPs) >300 bases in length for the assay, and the increased length of these probes allowed for the capture of human sequences up to 500 bp in length, which is optimal for capturing most human exons. To engineer the LPPs, we developed a method that generates ssDNA molecules with precise ends, using an appropriately designed dsDNA template. The template has appropriate restriction sites engineered into it that can be digested to generate nucleotide overhangs that are suitable for lambda exonuclease digestion, producing a single-stranded probe from dsDNA. The SMART technology is flexible and can be easily adapted to multiplex tens of thousands of target sequences in a single reaction.