Patent ID: 7179594

Claim:
A method for distinguishing between 5-position methylation changes of cytosine bases and cytosine-to-thymine mutations and detecting cytosine-to-thymine single nucleotide polymorphisms or point mutations, said method comprising the steps of: a) providing a first genomic DNA sample; b) providing a second genomic DNA sample, said first and second genomic DNA samples being identical to one another; c) treating said second genomic DNA sample, but not said first genomic DNA sample, with a methyltransferase, whereby all previously unmethylated cytosine bases in said second genomic DNA sample become methylated; d) chemically treating each of the first genomic DNA sample and the second genomic DNA sample treated with methyltransferase in step (c), with sulfite or bisulfite such that all of the unmethylated cytosine bases are changed whereas the methylated cytosine bases remain unchanged; e) determining the positions of cytosine in each of the first and second genomic DNA samples produced in step (d) using the same analytical method; f) comparing the cytosine positions of the first and second genomic DNA samples determined in step (e) to a reference DNA sequence and distinguishing 5-position methylation changes of cytosine bases and cytosine-to-thymine mutations; and g) detecting cytosine-to-thymine single nucleotide polymorphisms (SNPs) or point mutations in genomic DNA.