Epigenetics

is concerned with mechanisms which regulate gene activity

Although the cells of a multicellular organism are genetically identical, they are able to differentiate into many different cell and tissue types due to different gene activity. Epigenetics is concerned with the mechanisms which control this gene activity in the cell – mechanisms that switch individual genes and/or gene segments on or off without changing the DNA sequence. This gives rise to superordinate expression patterns which are not predefined in the gene sequence and which can be passed on from cells to daughter cells and from parent generations to their offspring.

How genetic and epigenetic regulatory mechanisms interact and how genetic information influenced by external signals affects the development and individual profile of an organism is little understood. Research findings in recent years have shown that an individual is more than the sum of its genes; this has been illustrated by studies of identical (monozygotic) twins, for example, who can develop quite different disease profiles and life prognoses.

DNA methylation, RNA interference and histone modification are among the most important epigenetic regulatory mechanisms.