Multiplex Asymmetric PCR by Combining the Amplification Refractory Mutation System with the Homo-Tag-Assisted Nondimer System.

ABSTRACT

Asymmetric PCR is widely used to produce single-stranded amplicons (ss-amplicons) for various downstream applications. However, conventional asymmetric PCR schemes are susceptible to events that affect primer availability, which can be exacerbated by multiplex amplification. In this study, a new multiplex asymmetric PCR approach that combines the amplification refractory mutation system (ARMS) with the homo-Tag-assisted nondimer system (HANDS) is described. ARMS-HANDS (A-H) PCR utilizes equimolar-tailed forward and reverse primers and an excess Tag primer. The tailed primer pairs initiate exponential symmetric amplification, whereas the Tag primer drives linear asymmetric amplification along fully matched strands but not one-nucleotide mismatched strands, thereby generating excess ss-amplicons. The production of ss-amplicons is validated using agarose gel electrophoresis, sequencing, and melting curve analysis. Primer dimer alleviation is confirmed by both the reduced Loss function value and a 20-fold higher sensitivity in an 11-plex A-H PCR assay than in an 11-plex conventional asymmetric PCR assay. Moreover, A-H PCR demonstrates unbiased amplification by its allele quantitative ability in correct identification of all 31 trisomy 21 samples among 342 clinical samples. A-H PCR is a new generation of multiplex asymmetric amplification approach with various applications, especially when sensitive and quantitative detection is required.