Patent ID: 7189512

Claim:
A method of analyzing and identifying variants in DNA samples by utilizing the specificity of the base excision repair (BER) system enzymes comprising: (a) obtaining the DNA samples; (b) denaturing and renaturing the DNA samples to produce a heteroduplex; (c) recognizing mismatched base pairs in the heteroduplex; (d) cleaving the mismatched bases to produce abasic residues; (e) cleaving a sugar-phosphate backbone of the heteroduplex 5′ and/or 3′ to the abasic residues, wherein the recognizing step (c) and the cleavage steps (d) and (e) are performed by Mut Y; (f) removing the abasic residues; (g) generating a 3′-OH and a 5′-P site in the sugar-phosphate backbone leaving a single nucleotide gap in the DNA; (h) adding Kienow exo, dNTP and labeled ddNTP to insert a dNTP or a labeled ddNTP at the single nucleotide gap at the 3′-OH site of the sugar-phosphate backbone; (i) adding DNA ligase to ligate the heteroduplex where a dNTP was inserted; (j) terminating the heteroduplex where ddNTP was inserted; and (k) identifying the variants by performing urea electrophoresis (PAGE) to determine the length of the heteroduplexes and to identify the labeled ddNTP inserted; (l) interpreting the results utilizing the specificity of the base excision repair (BER) system enzymes to deduce original variants, wherein when Mut Y is used and ddCTP is detected as the result of the electrophoresis (PAGE), then A/G is deduced to be the original variants; if ddGTP is detected as the result of the electrophoresis (PAGE), then A/C is deduced to be the original variants.