Patent ID: 7229759

Claim:
A method for the detection of cytosine methylation in DNA samples, characterized in that the following steps are conducted: a genomic DNA sample, which comprises the DNA to be investigated as well as background DNA, is chemically treated in such a way that all unmethylated cytosine bases are converted to uracil, while 5-methylcytosine bases remain unchanged; the chemically treated DNA sample is amplified with the use of at least 2 primer oligonucleotides, as well as a polymerase and at least one blocking oligonucleotide or PNA oligomer which preferentially binds to a 5′-CG-3′ dinucleotide or a 5′-TG-3′ dinucleotide or a 5′-CA-3′ dinucleotide on the background DNA, whereby the DNA to be investigated is preferentially amplified over the background DNA as the template, and the amplified products are analyzed and the methylation status in the DNA to be investigated is concluded from the presence of an amplified product and/or from the analysis of the amplified product.