Patent ID: 7776524

Claim:
A method for minimizing nucleotide misincorporation in a primer extension assay, the method comprising the steps of: a) providing a heterogeneous nucleic acid sample comprising a target nucleic acid containing a predetermined position suspected of containing a first variant base and a second variant base; b) contacting the heterogeneous nucleic acid sample with a primer complementary to a region adjacent to the predetermined position, a first nucleotide and a second nucleotide, wherein the first nucleotide is complementary to the first variant base and the second nucleotide is complementary to the second variant base and is a chain terminator; c) providing a first polymerase that preferentially incorporates said first nucleotide and a second polymerase that preferentially incorporates said second nucleotide; d) extending said primer in a primer extension reaction, wherein the first polymerase preferentially incorporates said first nucleotide into the extended primer on a template containing the first variant base at the predetermined position and the second polymerase preferentially incorporates said second nucleotide into the extended primer on a template containing the second variant base at the predetermined position, thereby reducing misincorporation of the first nucleotide into the extended primer on the template containing the second variant base.