Overlapping PCR for bidirectional PCR amplification of specific alleles: A rapid one-tube method for simultaneously differentiating homozygotes and heterozygotes

Qiang Liu, Erik C. Thorland, John A. Heit, Steve S. Sommer

Research output: Contribution to journalArticle

139 Scopus citations

Abstract

Rapid detection of single-base changes is fundamental to molecular medicine. PASA (PCR amplification of specific alleles) is a rapid method of genotyping single-base changes, but one reaction is required for each allele. Bidirectional PASA (Bi-PASA) was developed to distinguish between homozygotes and heterozygotes in one PCR reaction by utilizing novel primer design with appropriate cycling conditions. In Bi-PASA, one of the alleles is amplified by a PASA reaction in one direction while the second allele is amplified by a PASA reaction in the opposite direction. Two outer (P and Q) and two inner allele-specific (A and B) primers are required. In heterozygotes, three segments are amplified: a segment of size AQ resulting from one allele, another segment of size PB resulting from the second allele, and a combined segment of size PQ. In homozygotes, segment PQ and either segments AQ or PB amplify. The two inner primers (A and B) contain a relatively short complementary region and a 10-nucleotide G+C-rich 5' tail. The inner primers 'switch' from low-efficiency to high-efficiency amplification when genomic DNA is replaced by previously amplified template DNA. In addition, the 5' tails prevent 'megapriming'. The parameters for optimizing BI-PASA were investigated in detail for common mutations in the human factor V and catechol-O-methyltransferase genes. Guidelines for optimization of Bi-PASA also were developed and tested in a prospective study. Three additional Bi-PASA assays were optimized rapidly by utilizing these guidelines. In conclusion, Bi-PASA is a simple and rapid method for detecting the zygosity of known mutations in a single PCR reaction.

Original languageEnglish (US)
Pages (from-to)389-398
Number of pages10
JournalGenome Research
Volume7
Issue number4
DOIs
StatePublished - Apr 1997

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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