The human DNA sequence has been read, now we know how the genome works and how to detect and cure genetic diseases, don’t we?
Unfortunately not – or fortunately if you are working in this area. While we know the sequence of bases for a number of reference and other genomes, not only are we far from knowing and understanding all the variations that can be found between different people and the consequences of the variations – but there are also other layers of information in the genome that we are only starting to understand. I am talking about the field of epigenetics here, which looks at molecular “tags” that are attached to the DNA at certain places and play a key role in activation or deactivation of the genes in these places. In contrast to the actual DNA sequence these markers are reversible and get altered during embryonic development and differentiation, i.e. when cells develop into a specific cell types, e.g. a skin cell. They also get modified in a less fortunate way as we get old and in certain disease conditions such as diabetes, inflammation or cancer. The study of these tags is called epigenetics, or epigenomics when applied to the entire human genome.
More specifically, these tags are molecular modifications, mostly methyl-groups that can be attached usually to the Cytosil DNA base and to histones, the proteins that the DNA is wrapped around to “get in shape”.
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