杏吧原创

THE nature versus nurture debate is getting a facelift this week, with the publication of a genetic map that promises to tell us which bits of us are set in stone by our DNA, and which bits we can affect by how we live our lives.

The new 鈥渆pigenomic鈥� map doesn鈥檛 just look at genes, but also the instructions that govern them. Compiled by a consortium of biologists and computer scientists, this information will allow doctors to pinpoint precisely which cells in the body are responsible for various diseases. It might also reveal how to adjust your lifestyle to counter a genetic predisposition to a particular disease.

鈥淭he epigenome is the additional information our cells have on top of genetic information,鈥� says lead researcher of the Massachusetts Institute of Technology. It is made of chemical tags that are attached to DNA and its packaging. These tags act like genetic controllers, influencing whether a gene is switched on or off, and play an instrumental role in shaping our bodies and disease.

Researchers are still figuring out exactly how and when epigenetic tags are added to our DNA, but the process appears to depend on environmental cues. We inherit some tags from our parents, but what a mother eats during pregnancy, for instance, might also change her baby鈥檚 epigenome. Others tags relate to the environment we are exposed to as children and adults. 鈥淭he epigenome sits in a very special place between nature and nurture,鈥� says Kellis.

Each cell type in our body has a different epigenome 鈥� in fact, the DNA tags are the reason why our cells come in such different shapes and sizes despite having exactly the same DNA. So for its map, the collected thousands of cells from different adult and embryonic tissues, and meticulously analysed all the tags.

So far, they have produced 127 epigenomes, each corresponding to a different cell type, from brain cells to skin cells. That鈥檚 a big advance on the 16 published in 2012 by the ENCODE project, which are included in the new map.

The consortium also cross-referenced these healthy epigenomes with previous data on the genetic components of dozens of diseases, including type 1 diabetes, Crohn鈥檚 disease, high blood pressure, inflammatory bowel disease and Alzheimer鈥檚 disease (see 鈥�Alzheimer鈥檚 epigenetics鈥�).

The results, says Kellis, allow doctors to see what cell types are likely to be disrupted in people with these conditions. For instance, they suggest disruptions in the epigenome of the brain鈥檚 cingulate gyrus cells may play a role in attention deficit hyperactivity disorder ().

of the University of Edinburgh, UK, says the work offers 鈥渋ncredibly valuable information which will be absorbed and debated for years to come鈥�. He suggests that one day doctors will look at your epigenomes during routine health checks to suss out how the nature versus nurture battle is playing out inside your cells. These scans would reveal your genetic predisposition to certain conditions, and how your lifestyle is affecting those risks.

By adjusting your choices accordingly, you will be able to delay disease, or minimise its effects for as long as possible. 鈥淚t鈥檚 not going to move any further forward the point at which your life ends, but make the years up to that point 鈥� years that are spent in physical decline 鈥� a whole lot better,鈥� says Meehan.

聯Epigenomic medicine won鈥檛 extend your life, but make the years spent in physical decline a whole lot better聰

鈥淵ou see this on Star Trek,鈥� he adds. 鈥淣obody lives any longer but they just seem to be healthier up to the point where life, unfortunately, passes away.鈥�

This article appeared in print under the headline 鈥淢ap tells us how life nudges genes鈥�