Methylated DNA Immunoprecipitation (MeDIP)
DNA methylation is a phenomenon implicated in numerous diseases, the most frequently studied of which is cancer. In mammals, methylation occurs at cytosine bases which are followed by a guanine base (CpG), principally in the form of 5-methylcytosine :
MeDIP is a technique that uses anti-methylcytosine antibodies which are coupled to magnetic beads to immunoprecipitate the regions that are sufficiently methylated.
Sample DNA is fragmented by sonication then antibodies are added. Once these have bonded to the methylcytosines, the methylated fragments are collected using a magnet, thus removing from the sample any unmethylated or weakly methylated fragments : the sample has thus been enriched with methylated sequences and is ready to be analysed using a sequencing technique. For better reproducibility, it is recommended to use a robot to perform MeDIP.
The French National Research Centre for Human Genomics (CNRGH), which is part of the F Jacob Institute of Biology at the CEA in Evry (near Paris), and the Toulouse platform, both have the necessary equipment to optimise this pre-sequencing step.
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