| 摘要 |
A method is described for the detection of cytosine methylation in DNA samples, which permits the analysis of DNA to be investigated in the presence of large quantities of background DNA of the same individual. In the first step, a genomic DNA is chemically treated, preferably with a bisulfite (=disulfite, hydrogen sulfite), in such a way that cytosine is converted into a base that is different in its base pairing behavior in the DNA duplex, while 5-methylcytosine remains unchanged. Then segments of the sample DNA are amplified by means of a polymerase reaction. The amplificates are cleaved selectively by enzymes at those position which have a methylation state in the DNA sample that is not characteristic for the DNA to be investigated further, but which is characteristic for background DNA. The DNA that is not cleaved by enzymes is now amplified in another polymerase reaction, and in this way, the DNA to be investigated is concentrated relative to the background DNA that is present. The amplificate is finally investigated with respect to its sequence properties and the methylation state in the DNA to be investigated in the genomic DNA sample is concluded therefrom.
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