Patent ID: 6524794
Filing Date: 2003-02-25
Classification: C12Q

Abstract:
A method of identifying perfectly-matched heterohybrid DNA fragments which comprise DNA that is identical by descent for two individuals, comprising:a) obtaining a sample of genomic DNA from each of two individuals, thereby providing a first sample of genomic DNA and a second sample of genomic DNA; b) contacting the first and the second sample of genomic DNA with restriction endonuclease, thereby forming a first and a second preliminary digest DNA sample, respectively; c) methylating a first preliminary digest DNA sample, thereby forming a methylated preliminary digest DNA sample; d) mixing the methylated preliminary digest DNA sample and the second preliminary digest DNA sample, thereby forming a DNA sample mixture; e) incubating the DNA sample mixture under conditions which allow denaturation of the DNA samples, thereby forming a denatured DNA sample mixture; f) incubating the denatured DNA sample mixture under conditions which allow re-annealing of the DNA samples, thereby forming an annealed DNA sample mixture comprising homohybrid DNA fragments and heterohybrid DNA fragments; g) contacting the annealed DNA sample mixture with restriction endonuclease to digest homohybrid DNA fragment, thereby forming a homohybrid-digested, annealed DNA sample mixture; and h) contacting the homohybrid-digested, annealed DNA sample mixture with endonuclease to cleave both strands of a mismatch-containing heterohybrid DNA fragments, wherein the endonuclease is a methylation-independent endonuclease that recognize all eight possible mismatches, the endonuclease comprising T7 endonuclease I or T4 endonuclease VII, thereby forming a mismatch-digested DNA sample mixture comprising perfectly-matched heterohybrid DNA fragments, without performing a benzoylated, naphthylated DEAE cellulose step, wherein the perfectly-matched heterohybrid DNA fragments comprise DNA fragments that are identical by descent for the two individuals.