Heterozygote and mutation detection by direct automated fluorescent DNA sequencing using a mutant Taq DNA polymerase

Biotechniques. 1996 Apr;20(4):676-83. doi: 10.2144/19962004676.


We describe a method for direct cycle sequencing of PCR fragments amplified from genomic DNA or cDNA. DNA sequencing template is amplified using PCR and oligonucleotide primers flanking the region of interest. The amplified fragment is directly cycle sequenced using fluorescent sequencing primers, Sanger dideoxy sequencing chemistry and an enzyme mixture of a mutant Taq DNA polymerase and thermostable pyrophosphatase. The sequence ladders produced are analyzed on a real-time, automated four-color sequencing system. The method produces sequence ladders from unpurified PCR fragments of sufficiently high quality such that heterozygotes can be reproducibly detected and identified by software that recognizes signal-strength patterns indicative of mixed-base positions.

MeSH terms

  • Base Sequence
  • DNA Mutational Analysis / methods*
  • DNA Primers / genetics
  • DNA-Directed DNA Polymerase / genetics*
  • Exons / genetics
  • Fluorescent Dyes
  • Genetic Carrier Screening / methods*
  • Humans
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • RNA-Dependent RNA Polymerase / genetics*
  • Sequence Analysis, DNA / methods*
  • Taq Polymerase


  • DNA Primers
  • Fluorescent Dyes
  • Taq Polymerase
  • RNA-Dependent RNA Polymerase
  • DNA-Directed DNA Polymerase