Methylation Analysis

While all cells of a given organism carry the same DNA sequence, the methylation status of DNA undergoes changes during cell differentiation with the following characteristics:

• The base cytosine is the target of methylation
• Only some regions of DNA become methylated or demethylated
• This occurs in specific patterns, that are unique and stable for every cell type

Therefore cell types can be characterized through their methylation pattern, comparable to a fingerprint. The methylation fingerprint is very stable – there are no changes over time in a certain differentiated cell type. This cell type-specific methylation pattern is also stable chemically, permitting accurate analyis of samples even after freezing or extended storage of DNA, cells, or tissue. These characteristics result in unprecedented technical advantages:

• Cell types and corresponding differentiation states can be characterized very reliably
• Purity of cell mixtures or tissue samples can be assessed
• Retrospective studies with previously frozen samples can be performed