What is Epigenetics?
Genetic information of the DNA is encoded in the sequence of four bases. It is more or less identical in all of our cells and stays constant throughout life. However, expression of specific genes is tightly regulated for each specific cell type. During differentiation and development some genomic regions are permanently activated or inactivated. This information is not encoded in the genetic sequence but “epi-genetically” by additional modifications on the DNA strand.
What is DNA methylation?
Various different types of epigenetic modifications have been described. The best studied mechanism is the addition of a methyl group to cytosines in the DNA sequence. Thereby, the cytosine is converted to 5-methylcytosine. These cytosines are often followed by a neighboring guanine – so called CpG sites. The common perception is that DNA methylation of gene promoters down-regulate its expression. DNA methylation patterns are very diverse even within individual genes. Cygenia therefore elaborated specific CpG sites which facilitate best description of cellular states.
How is DNA methylation analyzed?
For epigenetic diagnostics it is important to provide highest precision for the DNA methylation level at individual CpG sides. To this end, DNA needs to be isolated, and bisulfite treated to convert unmethylated cytosines into thymidine bases, whereas the 5-methylcytosine residues remain protected from this conversion. The thymidine to cytosine ratio is therefore indicative for DNA methylation of specific CpG sites. Cygenia has established robust assays based on pyrosequencing or MassARRAY to specifically analyze the relevant regions. The results are then integrated into mathematical models to combine the predictive power of several CpG sites.